First image of the black hole at the center of the Milky Way. This is the first image of Sagittarius A* (or Sgr A* for short), the supermassive black hole at the centre of our galaxy. It’s the first direct visual evidence of the presence of this black hole. It was captured by the Event Horizon Telescope (EHT), an array which linked together eight existing radio observatories across the planet to form a single “Earth-sized” virtual telescope. The telescope is named after the “event horizon”, the boundary of the black hole beyond which no light can escape. Although we cannot see the event horizon itself, because it cannot emit light, glowing gas orbiting around the black hole reveals a telltale signature: a dark central region (called a “shadow”) surrounded by a bright ring-like structure. The new view captures light bent by the powerful gravity of the black hole, which is four million times more massive than our Sun. The image of the Sgr A* black hole is an average of the different images the EHT Collaboration has extracted from its 2017 observations. Credit: EHT Collaboration

by Amy C. Oliver, National Radio Astronomy Observatory

MAY 12, 2022

At simultaneous press conferences around the world, including at a National Science Foundation-sponsored press conference at the U.S. National Press Club in Washington, D.C., astronomers have unveiled the first image of the supermassive black hole at the center of our own Milky Way galaxy. This result provides overwhelming evidence that the object is indeed a black hole and yields valuable clues about the workings of such giants, which are thought to reside at the center of most galaxies. The image was produced by a global research team called the Event Horizon Telescope (EHT) Collaboration, using observations from a worldwide network of radio telescopes.

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Space.com

NEWS RELEASE 7-APR-2022

AMERICAN PHYSICAL SOCIETY

In the last seven years, scientists at the LIGO-Virgo Collaboration (LVC) have detected 90 gravitational waves signals. Gravitational waves are perturbations in the fabric of spacetime that race outwards from cataclysmic events like the merger of binary black holes (BBH). In observations from the first half of the most recent experimental run, which continued for six months in 2019, the collaboration reported signals from 44 BBH events.

But outliers were hiding in the data. Expanding the search, an international group of astrophysicists re-examined the data and found 10 additional black hole mergers, all outside the detection threshold of the LVC’s original analysis. The new mergers hint at exotic astrophysical scenarios that, for now, are only possible to study using gravitational wave astronomy.

“With gravitational waves, we’re now starting to observe the wide variety of black holes that have merged over the last few billion years,” says Physicist Seth Olsen, a Ph.D. candidate at Princeton University who led the new analysis. Every observation contributes to our understanding of how black holes form and evolve, he says, and the key to recognizing them is to find efficient ways to separate the signals from the noise.

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Supermassive black holes orbiting each other very closely are expected to produce gravitational waves.Credit: NASA’s Goddard Space Flight Center/Science Photo Library

Davide Castelvecchi -  Nature

27.1.2022

Astronomers could be on the verge of detecting gravitational waves from distant supermassive black holes — millions or even billions of times larger than the black holes spotted so far — an international collaboration suggests. The latest results from several research teams suggest they are closing in on a discovery after two decades of efforts to sense the ripples in space-time through their effects on pulsars, rapidly spinning spent stars that are sprinkled across the Milky Way.

Gravitational-wave hunters are looking for fluctuations in the signals from pulsars that would reveal how Earth bobs in a sea of gravitational waves. Like chaotic ripples in water, these waves could be due to the combined effects of perhaps hundreds of pairs of black holes, each lying at the centre of a distant galaxy.

So far, the International Pulsar Timing Array (IPTA) collaboration has found no conclusive evidence of these gravitational waves. But its latest analysis — using pooled data from collaborations based in North America, Europe and Australia — reveals a form of ‘red noise’ that has the features researchers expected to see. The findings were published on 19 January in Monthly Notices of the Royal Astronomical Society [1].

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Credit RIT

Matt Williams  - Universe Today

3.2.2022

In February 2016, scientists with the Laser Interferometer Gravitational-Wave Observatory (LIGO) confirmed the first-ever detection of a gravitational wave event. Originally predicted by Einstein’s Theory of General Relativity, GWs result from mergers between massive objects – like black holes, neutron stars, and supermassive black holes (SMBHs). Since 2016, dozens of events have been confirmed, opening a new window to the Universe and leading to a revolution in astronomy and cosmology.

In another first, a team of scientists led by the Center for Computational Relativity and Gravitation (CCRG) announced that they may have detected a merger of two black holes with eccentric orbits for the first time. According to the team’s paper, which recently appeared in Nature Astronomy, this potential discovery could explain why some of the black hole mergers detected by the LIGO Scientific Collaboration and the Virgo Collaboration are much heavier than previously expected.

The team consisted of astrophysicists from the CCRG Rochester Institute of Technology, the Institute of Computational and Experimental Research in Mathematics (ICERM) at Brown University, and the University of Florida. As they indicate in their paper, the team took a fresh look at previous findings made in 2020, where they were part of the team that observed the most massive GW binary detected to date (GW190521). This consisted of two black holes that were about 85 and 66 Solar masses, respectively. This resulted in the formation of a black hole remnant of 142 solar masses.

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From outside a black hole, all the infalling matter will emit light and always is visible, while... [+] ANDREW HAMILTON, JILA, UNIVERSITY OF COLORADO

Ethan Siegel   Jun 1, 2019,

There are many terrifying ways that the Universe can destroy something. In space, if you tried to hold your breath, your lungs would explode; if you exhaled every molecule of air instead, you'd black out within seconds. In some locations, you'd freeze solid as the heat was sucked out of your body; in others it's so hot that your atoms would turn into a plasma. But of all the ways the Universe has to dispose of someone, I can think of none more fascinating than to send someone inside a black hole. So does Event Horizon Telescope scientist Heino Falcke, who asks:

[W]hat is it like to be/fall inside a rotating black hole? This is not observable, but calculable... I have talked with various people who have done these calculations, but I am getting old and keep forgetting things.

It's a tremendously interesting question, and one that science can answer. Let's find out.

According to our theory of gravity, Einstein's General Relativity, there are only three things that determine the properties of a black hole. They are the following:

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Can a fluid analogue of a black hole point physicists toward the theory of quantum gravity, or is it a red herring?

NATALIE WOLCHOVER  --  SCIENCE

IN A 1972 lecture at the University of Oxford, a young physicist named William Unruh asked the audience to imagine a fish screaming as it plunges over a waterfall. The water falls so fast in this fictitious cascade that it exceeds the speed of sound at a certain point along the way. After the fish tumbles past this point, the water sweeps its screams downward faster than the sound waves can travel up, and the fish can no longer be heard by its friends in the river above.

Something similar happens, Unruh explained, when you fall into a black hole. As you approach one of these super-dense objects, the fabric of space and time becomes increasingly curved—equivalent to strengthening gravity, according to Albert Einstein’s general theory of relativity. At a point of no return known as the “event horizon,” the space-time curvature becomes so steep that signals can no longer climb to the outside world. Within the event horizon, even light is held captive by the black hole’s gravity, rendering black holes invisible.

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Collisions of two neutron stars (illustrated) probably produce more of the universe’s heavy elements than similar collisions of a black hole and neutron star. A. SIMONNET/SONOMA STATE UNIV., LIGO, NSF (EDITED BY MIT NEWS)

By Emily Conover NOVEMBER 3, 2021 

The cosmic origins of elements heavier than iron are mysterious. One elemental birthplace came to light in 2017 when two neutron-rich dead stars collided and spewed out gold, platinum and other hefty elements (SN: 10/16/17). A few years later, a smashup of another neutron star and a black hole left scientists wondering which type of cosmic clash was the more prolific element foundry (SN: 6/29/21).

Now, they have an answer. Collisions of two neutron stars probably take the cake, scientists report October 25 in Astrophysical Journal Letters.

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A black hole (illustrated in black) and a neutron star (white) spiral inward before merging, producing ripples in spacetime (dark gray). MARK MYERS/OZGRAV/SWINBURNE UNIVERSITY

An elusive source of ripples in spacetime has finally been found

By Emily Conover JUNE 29, 2021

Caught in a fatal inward spiral, a neutron star met its end when a black hole swallowed it whole. Gravitational ripples from that collision spread outward through the cosmos, eventually reaching Earth. The detection of those waves marks the first reported sighting of a black hole engulfing the dense remnant of dead star. And in a surprise twist, scientists spotted a second such merger just days after the first.

Until now, all identified sources of gravitational waves were twos of a kind: either two black holes or two neutron stars, spiraling around one another before colliding and coalescing (SN: 1/21/21). The violent cosmic collisions create waves that stretch and squeeze the fabric of spacetime, undulations that can be sussed out by sensitive detectors.

The mismatched pairing of a black hole and neutron star was the final type of merger that scientists expected to find with current gravitational wave observatories. By pure coincidence, researchers spotted two of these events within 10 days of one another, the LIGO, Virgo and KAGRA collaborations report in the July 1 Astrophysical Journal Letters.

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Credit: EHT Collaboration, [CC BY 4.0]

Written by Sebastian H. Völkel and Nicola Franchini

The name “black hole” describes the incredible phenomena that light cannot escape away from it. Here, the gravitational pull is beyond any measure, meaning that there is no emission at all. The boundary of this region is called the event horizon. On the other hand, the light that only approaches but never passes the event horizon is strongly deflected and eventually follows highly bent orbits around the black hole, until some of it can be observed on Earth.

Albert Einstein’s general theory of relativity predicts the existence of black holes. The mass of these objects can span from tens to millions or even billions of times the mass of the Sun. The latter is referred to by astrophysicists as supermassive black holes. These monsters have a lot of astrophysical relevance since they dwell in the centers of most galaxies, including the Milky Way.

According to scientists, black holes are surrounded by very hot gas in the shape of disks that are constantly rotating around the black hole. While some gas spirals inwards from far-out regions of the disk, other gas of the inner region falls into the black hole. These mechanisms produce light, which either fall in the black hole or escape from the system. The closest thing to a picture of a black hole (which itself does not emit light) is a detailed measurement of the shining gas being swallowed by it. Ongoing developments in radio astronomy, computer simulations, and data analysis techniques make it possible to take images of supermassive black holes, as demonstrated by the Event Horizon Telescope Collaboration in the last few years.

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Image from a MAYA collaboration numerical relativity simulation of a neutron star-black hole (NSBH) binary merger, showing the disruption of the neutron star. Credit: Deborah Ferguson (UT Ausitn), Bhavesh Khamesra (Georgia Tech), and Karan Jani (Vanderbilt University).

News Release • June 29, 2021

For the first time, researchers have confirmed the detection of a collision between a black hole and a neutron star. In fact, the scientists detected not one but two such events occurring just 10 days apart in January 2020. The extreme events made splashes in space that sent gravitational waves rippling across at least 900 million light-years to reach Earth. In each case, the neutron star was likely swallowed whole by its black hole partner.

Gravitational waves are disturbances in the curvature of space-time created by massive objects in motion. During the five years since the waves were first measured, a finding that led to the 2017 Nobel Prize in Physics, researchers have identified more than 50 gravitational-wave signals from the merging of pairs of black holes and of pairs of neutron stars. Both black holes and neutron stars are the corpses of massive stars, with black holes being even more massive than neutron stars.

Now, in a new study, scientists have announced the detection of gravitational waves from two rare events, each involving the collision of a black hole and a neutron star. The gravitational waves were detected by the National Science Foundation's (NSF's) Laser Interferometer Gravitational-Wave Observatory (LIGO) in the United States and by the Virgo detector in Italy. The KAGRA detector in Japan, joined the LIGO-Virgo network in 2020, but was not online during these detections.

The first merger, detected on January 5, 2020, involved a black hole about 9 times the mass of our sun, or 9 solar masses, and a 1.9-solar-mass neutron star. The second merger was detected on January 15, and involved a 6-solar-mass black hole and a 1.5-solar-mass neutron star. The results were published today, June 29, in The Astrophysical Journal Letters.

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Link to ApJ publication

F. Elavsky and A. Geller/Northwestern Univ./LIGO-Virgo Collaboration

May 7, 2021• Physics 14, 67

The latest dataset from gravitational-wave observatories has enough events to allow researchers to study properties of the whole population of black holes.

Black holes (blue), neutron stars (orange), and compact objects of uncertain nature (gray) detected via gravitational waves through September 2019. Each binary merger involves three compact objects: the two coalescing objects and the final remnant. The vertical scale is in solar masses.

Less than six years after the first detection of gravitational waves, observations are becoming routine, with LIGO and Virgo logging black hole mergers more than once per week. At the APS April meeting, the LIGO-Virgo Collaboration (LVC) reported using their catalog of nearly 50 events to estimate the typical properties and histories of black holes. Measurements of black hole spins, for example, suggest that at least two different formation mechanisms are common for black hole binaries. These black hole “population” studies—akin to astronomers’ star surveys—are becoming a prized tool for gravitational-wave scientists, in addition to studies of individual events.

The black holes in the LVC catalog are stellar-mass black holes—the remnants of giant stars after they explode as supernovae. In the past, astronomers could spot these black holes only when they were in a binary orbit with a normal star, but the LIGO and Virgo observatories have revolutionized the field since 2015. “The vast majority of the stellar-mass black holes that we know about in the Universe [were detected via] gravitational waves,” said Carl Rodriguez of Carnegie Mellon University, Pennsylvania, in his presentation at the conference. So gravitational waves are now the main source of data from which astrophysicists will learn about these objects. “For the first time, we’re able to do astronomy” using gravitational waves, said Maya Fishbach of Northwestern University, Illinois, a member of the LVC. “We’re really going to learn more about star formation in general.”

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Wormholes are fascinating (but theoretical) cosmological objects that can connect two distant regions of the universe. They would allow one to create “shortcuts” through space in order to travel vast distances in a shorter period of time. They are predicted by the general Theory of Relativity, and are what Einstein referred to as “bridges” through space-time. Wormholes are mathematically predicted, if not proven, and a new study illustrates how scientists have taken these theoretical anomalies – which many physicists believe to be real – and created one for them.

Researchers in Spain, from the physics department at the Autonomous University of Barcelona, have actually created a magnetic wormhole in a lab that tunnels a magnetic field through space.
Using matematerials and metasurfaces, our wormhole transfers the magnetic field from one point in space to another through a path that is magnetically undetectable. We experimentally show that the magnetic field from a source at one end of the wormhole appears at the other end as an isolated magnetic monopolar field, creating the illusion of a magnetic field propagating through a tunnel outside the 3D space.

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 A view of the M87 supermassive black hole in polarised light  EHT Collaboration/ESO

The first picture of a black hole’s shadow just got even more interesting. The Event Horizon Telescope (EHT) collaboration released the first direct image of a black hole in 2019, and while the picture on its own was impressive, it wasn’t the scientific smorgasbord some had hoped for. Now, researchers have added polarised light to the picture, giving us an idea of how magnetic fields around a supermassive black hole create powerful jets of matter.

“It was not a lot of information about the actual physics of the gas around the black hole,” says Sara Issaoun, an EHT team member at Radboud University in the Netherlands. “Looking at it in polarised light told us information about the magnetic field of the black hole.”

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Journal references

The globular cluster NGC 6397 is one of the closest to Earth at a distance of 7,800 light years. Analysis of multiple observations over several years with the Hubble Space Telescope reveals the gravitational effects of multiple stellar-mass black holes. Image: NASA, ESA, T. Brown, S. Casertano, and J. Anderson (STScI)

11 February 2021 Astronomy Now

Black holes are thought to range between two extremes: from stellar-mass black holes that form when single, massive stars collapse to the supermassive behemoths millions to billions of times the mass of the Sun. Intermediate-mass holes, with the gravitational heft of hundreds to tens of thousands of stars, are thought to bridge the gap between the two extremes, but only a few candidates have been identified to date.

Likely habitats for intermediate black holes are the cores of globular clusters, the concentrated assemblies of ancient stars that are nearly as old as the cosmos. Researchers using the Hubble Space Telescope observed one of the closest globulars to Earth – NGC 6397 – looking for stellar motions that might indicate the gravitational influence of an intermediate black hole.

Instead, they were surprised to find signs of multiple stellar-mass black holes.

“We found very strong evidence for an invisible mass in the dense core of the globular cluster, but we were surprised to find that this extra mass is not ‘point-like’ but extended to a few percent of the size of the cluster,” said Eduardo Vitral of the Paris Institute of Astrophysics.

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Science and Nature  7.2.2021

You don’t have to know a whole lot about science to know that black holes normally suck things in, not spew things out. But NASA detected something mighty bizarre at the supermassive black hole Markarian 335. Two of NASA’s space telescopes, including the Nuclear Spectroscopic Telescope Array (NuSTAR), amazingly observed a black hole’s corona “launched” away from the supermassive black hole.

Then an enormous pulse of X-ray energy spewed out. This kind of phenomena has never been observed before.
“This is the first time we have been able to link the launching of the corona to a flare. This will help us comprehend how supermassive black holes power some of the brightest objects in the cosmos.” Dan Wilkins, of Saint Mary’s University, said. This is one of the most important discoveries so far.

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Gravitational waves, produced when behemoths like black holes and neutron stars spiral inward and merge, have been spotted 50 times (each event represented with a large circle above). NADIEH BREMER/VISUALCINNAMON.COM

By Emily Conover and Nadieh Bremer

Fifty events reveal the similarities and differences in these cosmic smashups

Throughout the universe, violent collisions of cosmic beasts such as black holes wrench the fabric of spacetime, producing ripples called gravitational waves. For most of history, humans have been oblivious to those celestial rumbles. Today, we’ve detected scores of them.

The first came in 2015, when scientists with the Advanced Laser Interferometer Gravitational-Wave Observatory, or LIGO, spotted gravitational waves spawned from the merger of two black holes. That event rattled the bones of the cosmos — shaking the underlying structure of space and time. The detection also stirred up astronomy, providing a new way to observe the universe, and verified a prediction of Albert Einstein’s general theory of relativity (SN: 2/11/16).

The first came in 2015, when scientists with the Advanced Laser Interferometer Gravitational-Wave Observatory, or LIGO, spotted gravitational waves spawned from the merger of two black holes. That event rattled the bones of the cosmos — shaking the underlying structure of space and time. The detection also stirred up astronomy, providing a new way to observe the universe, and verified a prediction of Albert Einstein’s general theory of relativity (SN: 2/11/16).

But like a lone ripple in a vast sea, a single detection can tell scientists only so much. Now, LIGO and its partner observatory Advanced Virgo have collected 50 sets of gravitational waves. Most of these spacetime ripples resulted from two black holes spiraling inward before colliding. Some arose from collisions of dense stellar corpses called neutron stars. Two collisions involve celestial bodies that can’t be confidently identified, hinting that scientists may have spotted the first merger of a neutron star with a black hole (SN: 6/23/20).

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MICHELLE STARR 18 DECEMBER 2020

The Universe is full of galaxy clusters, but Abell 2261 is in a class of its own. In the galaxy in the centre of the cluster, where there should be one of the biggest supermassive black holes in the Universe, astronomers have been able to find no trace of such an object.

And a new search has only made the absence more puzzling: if the supermassive black hole got yeeted out into space, it should have left evidence of its passage. But there's no sign of it in the material surrounding the galactic centre, either.

But this means that constraints can be placed on what the supermassive black hole - if it is there, evading detection - is doing.

Galaxy clusters are the largest known gravitationally bound structures in the Universe. Typically, they're groups of hundreds to thousands of galaxies that are bound together, with one huge, abnormally bright galaxy at or close the centre, known as the brightest cluster galaxy (BCG).

But even among BCGs, Abell 2261's BCG (named, in fact, A2261-BCG, and located about 2.7 billion light-years away) stands out. It's about a million light-years across - up to to 10 times the size of the Milky Way galaxy - and it has a huge, puffy core 10,000 light-years across, the largest galactic core ever seen.

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This illustration generated by a computer model shows multiple black holes found within the heart of a dense globular star cluster. Credit: Aaron M. Geller, Northwestern University/CIERA

New analysis of gravitational-wave data leads to wealth of discoveries.

An international research collaboration including Northwestern University astronomers has produced the most detailed family portrait of black holes to date, offering new clues as to how black holes form. An intense analysis of the most recent gravitational-wave data available led to the rich portrait as well as multiple tests of Einstein’s theory of general relativity. (The theory passed each test.)

The team of scientists who make up the LIGO Scientific Collaboration (LSC) and the Virgo Collaboration is now sharing the full details of its discoveries. This includes new gravitational-wave detection candidates which held up to scrutiny — a whopping total of 39, representing a variety of black holes and neutron stars — and new discoveries as a result of combining all the observations. The 39 events averaged more than one per week of observing.

The observations could be a key piece in solving the many mysteries of exactly how binary stars interact. A better understanding of how binary stars evolve has consequences across astronomy, from exoplanets to galaxy formation.

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Scientists have now detected 50 sets of gravitational waves, many produced when two black holes (illustrated) spiral around one another before colliding and merging into one.
© N. FISCHER, S. OSSOKINE, H. PFEIFFER, A. BUONANNO/MAX PLANCK INSTITUTE FOR GRAVITATIONAL PHYSICS, SIMULATING EXTREME SPACETIMES (SXS) COLLABORATION

By Emily Conover OCTOBER 28, 2020 

Earth is awash in gravitational waves.

Over a six-month period, scientists captured a bounty of 39 sets of gravitational waves. The waves, which stretch and squeeze the fabric of spacetime, were caused by violent events such as the melding of two black holes into one.

The haul was reported by scientists with the LIGO and Virgo experiments in several studies posted October 28 on a collaboration website and at arXiv.org. The addition brings the tally of known gravitational wave events to 50.

The bevy of data, which includes sightings from April to October 2019, suggests that scientists’ gravitational wave–spotting skills have leveled up. Before this round of searching, only 11 events had been detected in the years since the effort began in 2015. Improvements to the detectors — two that make up the Advanced Laser Interferometer Gravitational-Wave Observatory, or LIGO, in the United States, and another, Virgo, in Italy — have dramatically boosted the rate of gravitational wave sightings.

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This year's Nobel Prize in Physics was awarded to Roger Penrose, Reinhard Genzel and Andrea Ghez.

By Emma Reynolds and Katie Hunt, CNN, October 6, 2020

(CNN)The 2020 Nobel Prize in Physics has been awarded to scientists Roger Penrose, Reinhard Genzel and Andrea Ghez for their discoveries about black holes.

Göran K. Hansson, secretary for the Royal Swedish Academy of Sciences, said at Tuesday's ceremony in Stockholm that this year's prize was about "the darkest secrets of universe."

Penrose, a professor at the University of Oxford who worked with Stephen Hawking, was awarded half of the prize "for the discovery that black hole formation is a robust prediction of the general theory of relativity." The other half was awarded jointly to Genzel and Ghez "for the discovery of a supermassive compact object at the center of our galaxy."

"Penrose, Genzel and Ghez together showed us that black holes are awe-inspiring, mathematically sublime, and actually exist," Tom McLeish, professor of natural philosophy at the University of York, told the Science Media Centre in London.

Ghez, born in New York City and a professor at the University of California, Los Angeles, is only the fourth woman to win a Nobel physics prize. It was awarded to a woman for the first time in 55 years in 2018, when Donna Strickland won for groundbreaking inventions in the field of laser physics.

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From the Royal Swedish Academy of Sciences

1  Original announcement

2  Scientific Background

3  Popular Science  Background

Snapshots of the appearance of M87 *, obtained with images and geometrical models and the EHT array between 2009 and 2017. The diameter of the rings is the same, but the location of the bright side varies. - (Image Credit: M. Wielgus, D. Pesce & the EHT Collaboration)

September 23, 2020

The Event Horizon Telescope is an array of telescopes that uses a technique called Very Long Baseline Interferometry (VLBI) to form a virtual radio telescope with a dish diameter similar to the size of Earth.

In the period between 2009-2013, M87* (the supermassive black hole in the galaxy M87) was observed with prototype EHT telescopes, at four different sites. Eventually, the entire EHT array came into operation in 2017, with seven telescopes located in five locations around the Earth.

Although the observations from 2009-2013 contained much less data than those from 2017 (lacking the capacity to provide a picture of the black hole at that point in time), the EHT team was able to identify changes in the appearance of M87* between 2009 and 2017 using statistical models.

The researchers concluded that the diameter of the black hole's shadow remains consistent with the predictions of Einstein's general theory of relativity for black holes of 6.5 billion solar masses. But they also found something unexpected: the crescent-shaped ring of hot plasma around M87* wobbles! It is the first time astronomers have glimpsed the dynamic accretion structure so close to the event horizon of a black hole, where gravity is extreme.

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An artist's impression of the last moments before the merger of two black holes. Credit: LIGO-VIRGO COLLABORATION

Jonathan Amos  -- BBC Science Correspondent
2 September 2020

Imagine the energy of eight Suns released in an instant.

This is the gravitational "shockwave" that spread out from the biggest merger yet observed between two black holes.
The signal from this event travelled for some seven billion years to reach Earth but was still sufficiently strong to rattle laser detectors in the US and Italy in May last year.
Researchers say the colliding black holes produced a single entity with a mass 142 times that of our Sun.
This is noteworthy. Science has long traced the presence of black holes on the sky that are quite a bit smaller or even very much larger. But this new observation inaugurates a novel class of so-called intermediate-sized black holes in the range of 100-1,000 Sun (or solar) masses.
The analysis is the latest to come out of the international LIGO-VIRGO collaboration, which operates three super-sensitive gravitational wave-detection systems in America and Europe.

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The link for the article in PRL 

© Carl Knox, ARC Centre of Excellence for Gravitational Wave Discovery (OzGrav)

23 June 2020

Scientists puzzle over the mysterious astrophysical object: have they discovered the heaviest neutron star or the lightest black hole ever observed?

An international team of scientists including Lancaster University have discovered a compact object lying between neutron stars and black holes in terms of mass.

When the most massive stars die, they collapse under their own gravity and leave behind black holes; when stars that are a bit less massive die, they explode in a supernova and leave behind dense, dead remnants of stars called neutron stars.

For decades, astronomers have been puzzled by a gap that lies between neutron stars and black holes: the heaviest known neutron star is no more than 2.5 times the mass of our sun, or 2.5 solar masses, and the lightest known black hole is about 5 solar masses.

The question remained: does anything lie in this so-called mass gap?

Now, in a new study from the National Science Foundation's Laser Interferometer Gravitational-Wave Observatory (LIGO) and the Virgo detector in Europe, scientists have announced the discovery of an object of 2.6 solar masses, placing it firmly in the mass gap.

The object was found on August 14, 2019, as it merged with a black hole of 23 solar masses, generating a splash of gravitational waves detected back on Earth by LIGO and Virgo. A paper about the detection has been accepted for publication in The Astrophysical Journal Letters.

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See the same news from Virgo website

See the same news from LIGO website

Marek Abramowicz, Michał Bejger, Éric Gourgoulhon & Odele Straub

Our existence in the Universe resulted from a rare combination of circumstances. The same must hold for any highly developed extraterrestrial civilisation, and if they have ever existed in the Milky Way, they would likely be scattered over large distances in space and time. However, all technologically advanced species must be aware of the unique property of the galactic centre: it hosts Sagittarius A* (Sgr A*), the closest supermassive black hole to anyone in the Galaxy. A civilisation with sufficient technical know-how may have placed material in orbit around Sgr A* for research, energy extraction, and communication purposes. In either case, its orbital motion will necessarily be a source of gravitational waves. We show that a Jupiter-mass probe on the retrograde innermost stable circular orbit around Sgr A* emits, depending on the black hole spin, at a frequency of fGW = 0.63–1.07 mHz and with a power of PGW = 2.7 × 10^36–2.0 × 10^37 erg/s. We discuss that the energy output of a single star is sufficient to stabilise the location of an orbiting probe for a billion years against gravitational wave induced orbital decay. Placing and sustaining a device near Sgr A* is therefore astrophysically possible. Such a probe will emit an unambiguously artificial continuous gravitational wave signal that is observable with LISA-type detectors.

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A visualization of a collision between two differently sized black holes.

Credit: N. Fischer, H. Pfeiffer, A. Buonanno (Max Planck Institute for Gravitational Physics), Simulating eXtreme Spacetimes (SXS) Collaboration

Davide Castelvecchi,  20 APRIL 2020

Gravitational-wave astronomers have for the first time detected a collision between two black holes of substantially different masses — opening up a new vista on astrophysics and on the physics of gravity. The event offers the first unmistakable evidence from these faint space-time ripples that at least one black hole was spinning before merging, giving astronomers rare insight into a key property of these these dark objects.

“It’s an exceptional event,” said Maya Fishbach, an astrophysicist at the University of Chicago in Illinois. Similar mergers on which data have been published all took place between black holes with roughly equal masses, so this new one dramatically upsets that pattern, she says. The collision was detected last year, and was unveiled on 18 April by Fishbach and her collaborators at a virtual meeting of the American Physical Society, held entirely online because of the coronavirus pandemic.

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A star's rosette-shaped path around a black hole confirms Einstein's theory of gravity. Rather than tracing out a single ellipse (red), its orbit rotates over time (blue, rotation exaggerated in this illustration for emphasis). L. CALÇADA/ESO

Decades of observations revealed the rotation of the star’s elliptical orbit

Emily Conover - ScienceNews

The first sign that Albert Einstein’s theory of gravity was correct has made a repeat appearance, this time near a supermassive black hole.

In 1915, Einstein realized that his newly formulated general theory of relativity explained a weird quirk in the orbit of Mercury. Now, that same effect has been found in a star’s orbit of the enormous black hole at the heart of the Milky Way, researchers with the GRAVITY collaboration report April 16 in Astronomy & Astrophysics.

The star, called S2, is part of a stellar entourage that surrounds the Milky Way’s central black hole. For decades, researchers have tracked S2’s elliptical motion around the black hole. The researchers previously had used observations of S2 to identify a different effect of general relativity, the reddening of the star’s light due to what’s called gravitational redshift (SN: 7/26/18).

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This simulation shows the radiation emitted from a binary black hole system. In principle, we should have neutron star binaries, black hole binaries, and neutron star-black hole systems, covering the entire allowable mass range. In practice, we saw a longstanding 'gap' in such binaries between about 2.5 and 5 solar masses. With the newest LIGO data, that gap seems to disappear.NASA'S GODDARD SPACE FLIGHT CENTER

Ethan Siegel

Mar 20, 2020

On Monday, March 16, 2020, astrophysicist Carl Rodriguez expressed a sentiment echoed by gravitational wave physicists all across the world: NOT NOW LIGO! Just minutes earlier, the LIGO collaboration sent out an alert suggesting that it had just detected another gravitational wave event, the 56th candidate detection since starting up its latest data-taking run in April of 2019. This one appears to indicate the merger of two black holes, like so many others before it.

Unlike most of the others, however, this one might be the nail-in-the-coffin of the idea of a "mass gap" between neutron stars and black holes. Before LIGO turned back on last April, all of its events, combined with otherwise-known neutron stars and black holes, showed two distinct populations: low-mass neutron stars (below 2.5 solar masses) and high-mass black holes (5 solar masses and up). This latest event, however, falls right into the mass gap range, and could demolish the idea once and for all.

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An artist’s conception of two black holes entwined in a gravitational tango. Credit: NASA/JPL-Caltech/SwRI/MSSS/Christopher Go

Do supermassive black holes have friends? The nature of galaxy formation suggests that the answer is yes, and in fact, pairs of supermassive black holes should be common in the universe.

I am an astrophysicist and am interested in a wide range of theoretical problems in astrophysics, from the formation of the very first galaxies to the gravitational interactions of black holes, stars and even planets. Black holes are intriguing systems, and supermassive black holes and the dense stellar environments that surround them represent one of the most extreme places in our universe.

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A black hole (one illustrated) with a mass equal to about 68 suns has been found in the Milky Way, researchers say. That dark mass is much heavier than other similar black holes. (NAOJ)

By Christopher Crockett 28.11.2019

A heavyweight black hole in our galaxy has some explaining to do.

With a mass of about 68 suns, it is far heftier than other stellar-mass black holes (those with masses below about 100 suns) in and around the Milky Way, scientists say. That’s not just a record, it’s also a conundrum. According to theory, black holes in our galaxy that form from the explosive deaths of massive stars — as this one likely did — shouldn’t be heavier than about 25 suns.

The black hole is locked in orbit with a young blue star dubbed LB-1, which sits about 13,800 light-years away in the constellation Gemini, researchers found. Combing through data from the LAMOST telescope in China, Jifeng Liu, an astrophysicist at the Chinese Academy of Sciences in Beijing, and colleagues noticed that LB-1 repeatedly moves toward and away from Earth with great speed — a sign that the star orbits something massive.

With additional observations from telescopes in Hawaii and the Canary Islands, the team mapped out the orbit and deduced that the star gets whipped around by a dark mass roughly 68 times as massive as the sun. Only a black hole fits that description, the team reports November 27 in Nature.

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Scientists have obtained the first image of a black hole, using Event Horizon Telescope observations of the center of the galaxy M87. The image shows a bright ring formed as light bends in the intense gravity around a black hole that is 6.5 billion times more massive than the Sun. This long-sought image provides the strongest evidence to date for the existence of supermassive black holes and opens a new window onto the study of black holes, their event horizons, and gravity. Credit: Event Horizon Telescope Collaboration

https://www.youtube.com/watch?v=3QEPzP58neg&feature=youtu.be

2020 Breakthrough Prize in Fundamental Physics

The Event Horizon Telescope Collaboration

Collaboration Director Shep Doeleman of the Harvard-Smithsonian Center for Astrophysics will accept on behalf the collaboration. The $3 million prize will be shared equally with 347 scientists co-authoring any of the six papers published by the EHT on April 10, 2019, which can be found here. The names are also listed at the bottom of this page.
Citation: For the first image of a supermassive black hole, taken by means of an Earth-sized alliance of telescopes.
Description: Using eight sensitive radio telescopes strategically positioned around the world in Antarctica, Chile, Mexico, Hawaii, Arizona and Spain, a global collaboration of scientists at 60 institutions operating in 20 countries and regions captured an image of a black hole for the first time. By synchronizing each telescope using a network of atomic clocks, the team created a virtual telescope as large as the Earth, with a resolving power never before achieved from the surface of our planet. One of their first targets was the supermassive black hole at the center of the Messier 87 galaxy – its mass equivalent to 6.5 billion suns. After painstakingly analyzing the data with novel algorithms and techniques, the team produced an image of this galactic monster, silhouetted against hot gas swirling around the black hole, that matched expectations from Einstein's theory of gravity: a bright ring marking the point where light orbits the black hole, surrounding a dark region where light cannot escape the black hole's gravitational pull.

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BLAST FROM COLLAPSE A collapsar occurs when a massive, spinning star collapses into a black hole, powering a blast of light known as a long gamma ray burst (illustrated) and exploding the star’s outer layers.

Spinning stellar objects collapsing into black holes could help explain heavy elements’ origins
BY EMILY CONOVER  MAY 8, 2019

The gold in your favorite jewelry could be the messy leftovers from a newborn black hole’s first meal.

Heavy elements such as gold, platinum and uranium might be formed in collapsars — rapidly spinning, massive stars that collapse into black holes as their outer layers explode in a rare type of supernova. A disk of material, swirling around the new black hole as it feeds, can create the conditions necessary for the astronomical alchemy, scientists report online May 8 in Nature.

“Black holes in these extreme environments are fussy eaters,” says astrophysicist Brian Metzger of Columbia University, a coauthor of the study. They can gulp down only so much matter at a time, and what they don’t swallow blows off in a wind that is rich in neutrons — just the right conditions for the creation of heavy elements, computer simulations reveal.

Astronomers have long puzzled over the origins of the heaviest elements in the universe. Lighter elements like carbon, oxygen and iron form inside stars, before being spewed out in stellar explosions called supernovas. But to create elements further down the periodic table, an extreme environment densely packed with neutrons is required. That’s where a chain of reactions known as the r-process can occur, in which atomic nuclei rapidly absorb neutrons and undergo radioactive decay to create new elements.

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NASA’S GODDARD SPACE FLIGHT CENTER/CI LAB

Astronomers still hope to catch a star going supernova and a bumpy neutron star, among others
BY LISA GROSSMAN 1:14PM, MAY 6, 2019

BANG, CRASH Physicists using the LIGO and Virgo observatories are catching all sorts of cosmic collisions, including of pairs of neutron stars (illustrated). But scientists hope to bag even more exotic quarry.

Seekers of gravitational waves are on a cosmic scavenger hunt.

Since the Advanced Laser Interferometer Gravitational-wave Observatory turned on in 2015, physicists have caught these ripples in spacetime from several exotic gravitational beasts — and scientists want more.

This week, LIGO and its partner observatory Virgo announced five new possible gravitational wave detections in a single month, making what was once a decades-long goal almost commonplace (SN Online: 5/2/19).

“We’re just beginning to see the field of gravitational wave astronomy open,” LIGO spokesperson Patrick Brady from the University of Wisconsin–Milwaukee said May 2 in a news conference. “Opening up a new window on the universe like this will hopefully bring us a whole new perspective on what’s out there.”

The speed and pitch of gravitational wave signals allow astronomers to make out what’s stirring up the waves. Here are the sources of gravitational waves that scientists that already have in their nets, and what they’re still hoping to find.

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Scientific simulation of a black hole consuming a neutron star.Credit: A. Tonita, L. Rezzolla, F. Pannarale

NATURE 26 APRIL 2019

Davide Castelvecchi

Gravitational waves may have just delivered the first sighting of a black hole devouring a neutron star. If confirmed, it would be the first evidence of the existence of such binary systems. The news comes just a day after astronomers had detected gravitational waves from a merger of two neutron stars for only the second time.

At 15:22:17 UTC on 26 April, the twin detectors of the Laser Interferometer Gravitational-wave Observatory (LIGO) in the United States and the Virgo observatory in Italy reported a burst of waves of an unusual type. Astronomers are still analysing the data and doing computer simulations to interpret them.

But they are already considering the tantalizing prospect that they have made a long-hoped-for detection that could produce a wealth of cosmic information, from precise tests of the general theory of relativity to measuring the Universe’s rate of expansion. Astronomers around the world are also racing to observe the phenomenon using different types of telescope.

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Scientific simulation of a black hole consuming a neutron star.Credit: A. Tonita, L. Rezzolla, F. Pannarale

NATURE 26 APRIL 2019

Davide Castelvecchi

Gravitational waves may have just delivered the first sighting of a black hole devouring a neutron star. If confirmed, it would be the first evidence of the existence of such binary systems. The news comes just a day after astronomers had detected gravitational waves from a merger of two neutron stars for only the second time.

At 15:22:17 UTC on 26 April, the twin detectors of the Laser Interferometer Gravitational-wave Observatory (LIGO) in the United States and the Virgo observatory in Italy reported a burst of waves of an unusual type. Astronomers are still analysing the data and doing computer simulations to interpret them.

But they are already considering the tantalizing prospect that they have made a long-hoped-for detection that could produce a wealth of cosmic information, from precise tests of the general theory of relativity to measuring the Universe’s rate of expansion. Astronomers around the world are also racing to observe the phenomenon using different types of telescope.

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EHT images of M87 on four different observing nights. In each panel, the white circle shows the resolution of the EHT. All four images are dominated by a bright ring with enhanced emission in the south. 

The Astrophysical Journal Letters

Shep Doeleman (EHT Director) on behalf of the EHT Collaboration -- April 2019

This Focus Issue shows ultra-high angular resolution images of radio emission from the supermassive black hole believed to lie at the heart of galaxy M87 (Figure 1). A defining feature of the images is an irregular but clear bright ring, whose size and shape agree closely with the expected lensed photon orbit of a 6.5 billion solar mass black hole. Soon after Einstein introduced general relativity, theorists derived the full analytic form of the photon orbit, and first simulated its lensed appearance in the 1970s. By the 2000s, it was possible to sketch the "shadow" formed in the image when synchrotron emission from an optically thin accretion flow is lensed in the black hole's gravity. During this time, observational evidence began to build for the existence of black holes at the centers of active galaxies, and in our own Milky Way. In particular, a steady progression in radio astronomy enabled very long baseline interferometry (VLBI) observations at ever-shorter wavelengths, targeting supermassive black holes with the largest apparent event horizons: M87, and Sgr A* in the Galactic Center. The compact sizes of these two sources were confirmed by studies at 1.3mm, first exploiting baselines that ran from Hawai'i to the mainland US, then with increased resolution on baselines to Spain and Chile.

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Credit: (agsandrew/iStock)

MIKE MCRAE 31 MAR 2019

Today our middle-aged Universe looks eerily smooth. Too smooth, in fact.

While a rapid growth spurt in space-time would explain what we see, science needs more than nice ideas. It needs evidence that whittles away contending arguments. We might finally know where to look for some.

A team of physicists from the Centre for Astrophysics | Harvard & Smithsonian (CfA) and Harvard University went back to the drawing board on the early Universe's evolution to give us a way to help those inflation models stand out from the crowd.

"The current situation for inflation is that it's such a flexible idea, it cannot be falsified experimentally," says theoretical physicist Avi Loeb from the CfA.

"No matter what value people measure for some observable attribute, there are always some models of inflation that can explain it."

We've been convinced for some time that our Universe is expanding – its fabric slowly stretching out under the influence of some kind of strange 'dark' energy.

If we press rewind on the Universe until it was barely 10^-43 seconds old, we arrive at the limit of what our knowledge of physics can handle. Before that moment? Geometry is so nuts, we just don't know where to start.

Running the calculations backward, we also find the Universe would have had a radius of 10^-10 metres at this crucial moment. That sounds tiny, sure, but it's not tiny enough.

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Credit: Kavli IPMU

MICHELLE STARR 4 APR 2019

We still don't know what dark matter is, but we can strike a line through one option. It is not, as per a theory proposed by the brilliant Stephen Hawking, a bunch of teeny-tiny microscopic black holes.

In the most rigorous test of the theory to date, an international team led by researchers from the Kavli Institute for the Physics and Mathematics of the Universe (IPMU) in Japan has searched for the telltale sign of such minuscule black holes, and the result was pretty damning.

The scientists were hunting for a particular flicker of stars in a nearby galaxy - the way the light would appear to us if a black hole less than a tenth of a millimetre were passing in front of it.

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The most-visualized black hole of all, as illustrated in the movie Interstellar, shows a predicted event horizon fairly accurately for a very specific class of rotating black holes. Deep within the gravitational well, time passes at a different rate for observers than it does for us far outside of it. The Event Horizon Telescope is expected to reveal the emissions surrounding a black hole's event horizon, directly, for the first time. INTERSTELLAR / R. HURT / CALTECH

Ethan Siegel
Apr 2, 2019

In science, there's no moment more exciting than when you get to confront a longstanding theoretical prediction with the first observational or experimental results. Earlier this decade, the Large Hadron Collider revealed the existence of the Higgs boson, the last undiscovered fundamental particle in the Standard Model. A few years ago, the LIGO collaboration directly detected gravitational waves, confirming a longstanding prediction of Einstein's General Relativity.

And in just a few days, on April 10, 2019, the Event Horizon Telescope will make a much-anticipated announcement where they're expected to release the first-ever image of a black hole's event horizon. At the start of the 2010s, such an observation would have been technologically impossible. Yet not only are we about to see what a black hole actually looks like, but we're about to test some fundamental properties of space, time, and gravity as well.

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1 April 2019

The European Commission, European Research Council, and the Event Horizon Telescope (EHT) project will hold a press conference to present a groundbreaking result from the EHT.

When: On 10 April 2019 at 15:00 CEST

Where: The press conference will be held at the Berlaymont Building, Rue de la Loi (Wetstraat) 200, B-1049 Brussels, Belgium. The event will be introduced by European Commissioner for Research, Science and Innovation, Carlos Moedas, and will feature presentations by the researchers behind this result.

What: A press conference to present a groundbreaking result from the EHT.

Who: The European Commissioner for Research, Science and Innovation, Carlos Moedas, will deliver remarks. Anton Zensus, Chair of the EHT Collaboration Board will also make remarks and introduce a panel of EHT researchers who will explain the result and answer questions:
        Heino Falcke, Radboud University, Nijmegen, The Netherlands (Chair of the EHT Science Council)
        Monika Mościbrodzka, Radboud University, Nijmegen, The Netherlands (EHT Working Group Coordinator)
        Luciano Rezzolla, Goethe Universität, Frankfurt, Germany (EHT Board Member)
        Eduardo Ros, Max-Planck-Institut für Radioastronomie, Bonn, Germany, (EHT Board Secretary)

RSVP: This invitation is addressed to media representatives. To participate in the conference, members of the media must register by completing an online form before April 7 23:59 CEST. Please indicate whether you wish to attend in person or if you will participate online only. On-site journalists will have a question-and-answer session with panellists during the conference. In-person individual interviews immediately after the conference will also be possible.
The conference will be streamed online on the ESO website, by the ERC, and on social media. We will take a few questions from social media using the hashtag #AskEHTeu.

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The observatories are also releasing their first catalog of gravitational-wave events

On Saturday, December 1, scientists attending the Gravitational Wave Physics and Astronomy Workshop in College Park, Maryland, presented new results from the National Science Foundation's LIGO (Laser Interferometer Gravitational-Wave Observatory) and the European- based VIRGO gravitational-wave detector regarding their searches for coalescing cosmic objects, such as pairs of black holes and pairs of neutron stars. The LIGO and Virgo collaborations have now confidently detected gravitational waves from a total of 10 stellar-mass binary black hole mergers and one merger of neutron stars, which are the dense, spherical remains of stellar explosions. Six of the black hole merger events had been reported before, while four are newly announced.

From September 12, 2015, to January 19, 2016, during the first LIGO observing run since undergoing upgrades in a program called Advanced LIGO, gravitational waves from three binary black hole mergers were detected. The second observing run, which lasted from November 30, 2016, to August 25, 2017, yielded one binary neutron star merger and seven additional binary black hole mergers, including the four new gravitational-wave events being reported now. The new events are known as GW170729, GW170809, GW170818, and GW170823, in reference to the dates they were detected.

All of the events are included in a new catalog, also released Saturday, with some of the events breaking records. For instance, the new event GW170729, detected in the second observing run on July 29, 2017, is the most massive and distant gravitational-wave source ever observed. In this coalescence, which happened roughly 5 billion years ago, an equivalent energy of almost five solar masses was converted into gravitational radiation.

GW170814 was the first binary black hole merger measured by the three-detector network, and allowed for the first tests of gravitational-wave polarization (analogous to light polarization).

The event GW170817, detected three days after GW170814, represented the first time that gravitational waves were ever observed from the merger of a binary neutron star system. What's more, this collision was seen in gravitational waves and light, marking an exciting new chapter in multi-messenger astronomy, in which cosmic objects are observed simultaneously in different forms of radiation.

One of the new events, GW170818, which was detected by the global network formed by the LIGO and Virgo observatories, was very precisely pinpointed in the sky. The position of the binary black holes, located 2.5 billion light-years from Earth, was identified in the sky with a precision of 39 square degrees. That makes it the next best localized gravitational-wave source after the GW170817 neutron star merger.

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A still image of a visualization of the merging black holes that LIGO and Virgo have observed so far. As the horizons of the black holes spiral together and merge, the emitted gravitational waves become louder (larger amplitude) and higher pitched (higher in frequency). The black holes that merge range from 7.6 solar masses up to 50.6 solar masses, with about 5% of the total mass lost during each merger.TERESITA RAMIREZ/GEOFFREY LOVELACE/SXS COLLABORATION/LIGO-VIRGO COLLABORATION

Dec 4, 2018,
Ethan Siegel Senior Contributor
Science

On September 14th, 2015, just days after LIGO first turned on at its new-and-improved sensitivity, a gravitational wave passed through Earth. Like the billions of similar waves that had passed through Earth over the course of its history, this one was generated by an inspiral, merger, and collision of two massive, ultra-distant objects from far beyond our own galaxy. From over a billion light years away, two massive black holes had coalesced, and the signal — moving at the speed of light — finally reached Earth.

But this time, we were ready. The twin LIGO detectors saw their arms expand-and-contract by a subatomic amount, but that was enough for the laser light to shift and produce a telltale change in an interference pattern. For the first time, we had detected a gravitational wave. Three years later, we've detected 11 of them, with 10 coming from black holes. Here's what we've learned.

There have been two "runs" of LIGO data: a first one from September 12, 2015 to January 19, 2016 and then a second one, at somewhat improved sensitivity, from November 30, 2016 to August 25, 2017. That latter run was, partway through, joined by the VIRGO detector in Italy, which added not only a third detector, but significantly improved our ability to pinpoint the location of where these gravitational waves occurred. LIGO is currently shut down right now, as it's undergoing upgrades that will make it even more sensitive, as it prepares to begin a new data-taking observing run in the spring of 2019.

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Five different simulations in general relativity, using a magnetohydrodynamic model of the black hole's accretion disk, and how the radio signal will look as a result. Note the clear signature of the event horizon in all the expected results.GRMHD SIMULATIONS OF VISIBILITY AMPLITUDE VARIABILITY FOR EVENT HORIZON TELESCOPE IMAGES OF SGR A*, L. MEDEIROS ET AL., ARXIV:1601.06799

Oct 3, 2018

Ethan Siegel & Starts With A Bang

What does a black hole actually look like? For generations, scientists argued over whether black holes actually existed or not. Sure, there were mathematical solutions in General Relativity that indicated they were possible, but not every mathematical solution corresponds to our physical reality. It took observational evidence to settle that issue.

Owing to matter orbiting and infalling around black holes, both stellar-mass versions and the supermassive versions, we've detected the X-ray emissions characteristic of their existences. We found and measured the motions of individual stars that orbit suspected black holes, confirming the existence of massive objects at the centers of galaxies. If only we could directly image these objects that emit no light themselves, right? Amazingly, that time is here.

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In this artistic rendering, a blazar emits both neutrinos and gamma rays that could be detected by the IceCube Neutrino Observatory as well as by other telescopes on Earth and in space. Credit: IceCube/NASA

By the IceCube Collaboration, 12 Jul 2018 10:00 AM

An international team of scientists has found the first evidence of a source of high-energy cosmic neutrinos, ghostly subatomic particles that can travel unhindered for billions of light years from the most extreme environments in the universe to Earth.
The observations, made by the IceCube Neutrino Observatory at the Amundsen–Scott South Pole Station and confirmed by telescopes around the globe and in Earth’s orbit, help resolve a more than a century-old riddle about what sends subatomic particles such as neutrinos and cosmic rays speeding through the universe.

Since they were first detected over one hundred years ago, cosmic rays—highly energetic particles that continuously rain down on Earth from space—have posed an enduring mystery: What creates and launches these particles across such vast distances? Where do they come from?
Because cosmic rays are charged particles, their paths cannot be traced directly back to their sources due to the powerful magnetic fields that fill space and warp their trajectories. But the powerful cosmic accelerators that produce them will also produce neutrinos. Neutrinos are uncharged particles, unaffected by even the most powerful magnetic field. Because they rarely interact with matter and have almost no mass—hence their sobriquet “ghost particle”—neutrinos travel nearly undisturbed from their accelerators, giving scientists an almost direct pointer to their source.

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Artist conception of a tidal disruption event (TDE) that happens when a star passes fatally close to a supermassive black hole, which reacts by launching a relativistic jet. (Sophia Dagnello, NRAO/AUI/NSF; NASA, STScI )

Andrew Griffin  15.06.2018

The huge, violent event sees a blast of matter shot across the universe

Scientists have seen the vast blast thrown out by a black hole eating a star for the first ever time.

Researchers have finally watched the formation and expansion of the fast-moving jet of material that is thrown out when a supermassive black hole's gravity grabs a star and tears it apart.

Scientists watched the dramatic event using highly specialised telescopes, which are trained on a pair of colliding galaxies called Arp 299, nearly 150 million light-years from Earth. At the centre of one of those galaxies, a star twice the size of the Sun came too close to a black hole that is more than 20 million times big as our Sun – and was shredded apart, throwing a blast across the universe.

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A 1998 illustration of a spacecraft using negative energy to warp space-time and travel faster than light (digital art by Les Bossinas (Cortez III Service Corp.), 1998)

Dave Mosher May 24, 2018

• The US Department of Defense funded a series of studies on advanced aerospace technologies, including warp drives.
• The studies came out of a program that also funded research into UFO sightings.
• One report describes the possibility of using dark energy to warp space and effectively travel faster than light.
• However, a theoretical physicist says there's "zero chance that anyone within our lifetimes or the next 1,000 years" will see it happen.

Sometime after August 2008, the US Department of Defense contracted dozens of researchers to look into some very, very out-there aerospace technologies, including never-before-seen methods of propulsion, lift, and stealth.

Two researchers came back with a 34-page report for the propulsion category, titled "Warp Drive, Dark Energy, and the Manipulation of Extra Dimensions."

The document is dated April 2, 2010, though it was only recently released by the Defense Intelligence Agency. (Business Insider first learned about in a post by Paul Szoldra at Task & Purpose.)

The authors suggest we may not be too far away from cracking the mysteries of higher, unseen dimensions and negative or "dark energy," a repulsive force that physicists believe is pushing the universe apart at ever-faster speeds.

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Mathematicians have disproved the strong cosmic censorship conjecture. Their work answers one of the most important questions in the study of general relativity and changes the way we think about space-time.

Kevin Hartnet   May 17, 2018

Nearly 60 years after it was proposed, mathematicians have settled one of the most profound questions in the study of general relativity. In a paper posted online last fall, mathematicians Mihalis Dafermos and Jonathan Luk have proven that the strong cosmic censorship conjecture, which concerns the strange inner workings of black holes, is false.

“I personally view this work as a tremendous achievement — a qualitative jump in our understanding of general relativity,” emailed Igor Rodnianski, a mathematician at Princeton University.

The strong cosmic censorship conjecture was proposed in 1979 by the influential physicist Roger Penrose. It was meant as a way out of a trap. For decades, Albert Einstein’s theory of general relativity had reigned as the best scientific description of large-scale phenomena in the universe. Yet mathematical advances in the 1960s showed that Einstein’s equations lapsed into troubling inconsistencies when applied to black holes. Penrose believed that if his strong cosmic censorship conjecture were true, this lack of predictability could be disregarded as a mathematical novelty rather than as a sincere statement about the physical world.

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Black holes in these environments could combine repeatedly to form objects bigger than anything a single star could produce.

Jennifer Chu | MIT News Office
April 10, 2018

When LIGO’s twin detectors first picked up faint wobbles in their respective, identical mirrors, the signal didn’t just provide first direct detection of gravitational waves — it also confirmed the existence of stellar binary black holes, which gave rise to the signal in the first place.
Stellar binary black holes are formed when two black holes, created out of the remnants of massive stars, begin to orbit each other. Eventually, the black holes merge in a spectacular collision that, according to Einstein’s theory of general relativity, should release a huge amount of energy in the form of gravitational waves.

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The center of the Milky Way galaxy, with the supermassive black hole Sagittarius A* (Sgr A*), located in the middle.
PHOTOGRAPH BY NASA/UMASS/D.WANG ET AL., STSCI

By Sarah Gibbens
PUBLISHED APRIL 4, 2018

A gaggle of black holes has been found clustered around the center of our home galaxy, the Milky Way—and the discovery hints at a much larger population of black holes hidden across the galaxy. The discover offers a new test bed for understanding the ripples in space-time known as gravitational waves.

For years, scientists have known that a monster black hole sits in the middle of the galaxy. Called Sagittarius A* (Sgr A*), the compact object is more than four million times as massive as our sun, but it's packed into a region of space no bigger than the distance between Earth and our star.

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March 22, 2018

Sabine Hossenfelder

We all dream the same dream, here in theoretical physics. We dream of the day when one of our equations will be plotted against data and fit spot on. It’s rare for this dream to come true. Even if it does, some don’t live to see it.

Take, for example, Albert Einstein, who passed away in 1955, 60 years before his equations’ most stunning consequence was confirmed: Space-time has periodic ripples — gravitational waves — that can carry energy across billions of light-years.

Since that September 2015 black hole collision, the Laser Interferometer Gravitational-Wave Observatory (LIGO) team has reported five more events (a sixth fell just short of the standard of significance). But the LIGO data is still virgin territory. It is an entirely new way of decoding the universe, and physicists must develop methods of data analysis along with the measurements.

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The black hole, as illustrated in the movie Interstellar, shows an event horizon fairly accurately for a very specific class of rotating black holes. Image credit: Interstellar / R. Hurt / Caltech.

The Event Horizon Telescope has come online and taken its data. Now, we wait for the results.

Black holes are some of the most incredible objects in the Universe. There are places where so much mass has gathered in such a tiny volume that the individual matter particles cannot remain as they normally are, and instead collapse down to a singularity. Surrounding this singularity is a sphere-like region known as the event horizon, from inside which nothing can escape, even if it moves at the Universe’s maximum speed: the speed of light. While we know three separate ways to form black holes, and have discovered evidence for thousands of them, we’ve never imaged one directly. Despite all that we’ve discovered, we’ve never seen a black hole’s event horizon, or even confirmed that they truly had one. Next year, that’s all about to change, as the first results from the Event Horizon Telescope will be revealed, answering one of the longest-standing questions in astrophysics.

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News Release • November 15, 2017

Scientists searching for gravitational waves have confirmed yet another detection from their fruitful observing run earlier this year. Dubbed GW170608, the latest discovery was produced by the merger of two relatively light black holes, 7 and 12 times the mass of the sun, at a distance of about a billion light-years from Earth. The merger left behind a final black hole 18 times the mass of the sun, meaning that energy equivalent to about 1 solar mass was emitted as gravitational waves during the collision.

This event, detected by the two NSF-supported LIGO detectors at 02:01:16 UTC on June 8, 2017 (or 10:01:16 pm on June 7 in US Eastern Daylight time), was actually the second binary black hole merger observed during LIGO’s second observation run since being upgraded in a program called Advanced LIGO. But its announcement was delayed due to the time required to understand two other discoveries: a LIGO-Virgo three-detector observation of gravitational waves from another binary black hole merger (GW170814) on August 14, and the first-ever detection of a binary neutron star merger (GW170817) in light and gravitational waves on August 17.

A paper describing the newly confirmed observation, “GW170608: Observation of a 19-solar-mass binary black hole coalescence,” authored by the LIGO Scientific Collaboration and the Virgo Collaboration has been submitted to The Astrophysical Journal Letters and is available to read on the arXiv. Additional information for the scientific and general public can be found at http://www.ligo.org/detections/GW170608.php.

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By Nicolas Arnaud  -- October 11, 2017

*** MEDIA ADVISORY ***
Issued jointly by the LIGO Laboratory, LIGO Scientific Collaboration, National Science Foundation, and Virgo Collaboration

Scientists representing LIGO, Virgo, and some 70 observatories will reveal new details and discoveries made in the ongoing search for gravitational waves.

WHAT: Journalists are invited to join the National Science Foundation as it brings together scientists from the LIGO and Virgo collaborations, as well as representatives for some 70 observatories, on Monday, October 16, at 16:00 CEST at the National Press Club in Washington, D.C.

The gathering will begin with an overview of new findings from LIGO, Virgo, and partners that span the globe, followed by details from telescopes that work with the LIGO and Virgo Collaboration to study extreme events in the cosmos.

The first detection of gravitational waves, made on September 14, 2015 and announced on February 11, 2016, was a milestone in physics and astronomy; it confirmed a major prediction of Albert Einstein’s 1915 general theory of relativity, and marked the beginning of the new field of gravitational-wave astronomy. Since then, there have been three more confirmed detections, one of which (and the most recently announced) was the first confirmed detection seen jointly by both the LIGO and Virgo detectors.

The published articles announcing LIGO-Virgo’s first, second, and third confirmed detections have been cited more than 1,700 times (total), according to the Web of Science citation counts. A fourth paper on the three-detector observation was published on October 6; a manuscript was made publicly available on September 27.

WHEN: Monday, October 16, 2017  16:00 CEST

** Panels to begin at 16:00 and 17:15, with a 15-minute break in between. Event expected to conclude by 18:30.

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A recent study provides a renewed look at whether the universe's dark matter could be primordial black holes — and, if so, whether LIGO could detect them. [dark matter. [SXS Lensing]

By Susanna Kohler on 27 September 2017 

Today promises to be an exciting day in the world of gravitational-wave detections. To keep with the theme, we thought we’d use this opportunity to take a renewed look at an interesting question about the Laser Interferometer Gravitational-Wave Observatory (LIGO) and dark matter: if dark matter is made up of primordial black holes, will LIGO be able to detect them?

Black Holes in the Early Universe

The black holes we generally think about in the context of gravitational-wave detections are black holes formed by the collapse of massive stars. Indeed, LIGO’s detections have thus far been of merging black holes weighing between 7 and 35 solar masses — the perfect sizes to have formed from massive-star collapses.

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News Release • September 27, 2017

The LIGO Scientific Collaboration and the Virgo collaboration report the first joint detection of gravitational waves with both the LIGO and Virgo detectors. This is the fourth announced detection of a binary black hole system and the first significant gravitational-wave signal recorded by the Virgo detector, and highlights the scientific potential of a three-detector network of gravitational-wave detectors.

The three-detector observation was made on August 14, 2017 at 10:30:43 UTC. The two Laser Interferometer Gravitational-Wave Observatory (LIGO) detectors, located in Livingston, Louisiana, and Hanford, Washington, and funded by the National Science Foundation (NSF), and the Virgo detector, located near Pisa, Italy, detected a transient gravitational-wave signal produced by the coalescence of two stellar mass black holes.

A paper about the event, known as GW170814, has been accepted for publication in the journal Physical Review Letters.

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See the paper

News Release • September 27, 2017

The LIGO Scientific Collaboration and the Virgo collaboration report the first joint detection of gravitational waves with both the LIGO and Virgo detectors. This is the fourth announced detection of a binary black hole system and the first significant gravitational-wave signal recorded by the Virgo detector, and highlights the scientific potential of a three-detector network of gravitational-wave detectors.

The three-detector observation was made on August 14, 2017 at 10:30:43 UTC. The two Laser Interferometer Gravitational-Wave Observatory (LIGO) detectors, located in Livingston, Louisiana, and Hanford, Washington, and funded by the National Science Foundation (NSF), and the Virgo detector, located near Pisa, Italy, detected a transient gravitational-wave signal produced by the coalescence of two stellar mass black holes.

A paper about the event, known as GW170814, has been accepted for publication in the journal Physical Review Letters.

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See the paper

The two compact radio sources separated by less than a light year at the center of the galaxyNGC7674. The two sources correspond to the location of the two active supermassive blackholes which form a binary and orbit around each other. Credit: TIFR-NCRA and RIT, USA

September 18, 2017 by Susan Gawlowicz

A study using multiple radio telescopes confirms that supermassive black holes found in the centers of galaxies can form gravitationally bound pairs when galaxies merge.

The paper published in the Sept. 18 issue of Nature Astronomy sheds light on a class of black holes having a mass upwards of one million times the mass of the sun. Supermassive black holes are expected to form tightly bound pairs following the merger of two galaxies.
"The dual black hole we found has the smallest separation of any so far detected through direct imaging," said David Merritt, professor of physics at Rochester Institute of Technology, a co-author on the paper.

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Using a massive telescope network, scientists have data in hand that could open new frontiers in our understanding of gravity.

Westford, MassachusettsFor the monster at the Milky Way’s heart, it’s a wrap.

After completing five nights of observations, today astronomers may finally have captured the first-ever image of the famous gravitational sinkhole known as a black hole.

More precisely, the hoped-for portrait is of a mysterious region that surrounds the black hole. Called the event horizon, this is the boundary beyond which nothing, not even light, can escape the object’s gargantuan grasp.

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HEART OF THE MATTER An illustration of the supermassive black hole at the center of the Milky Way.
PHOTOGRAPH BY NRAO, AUI, NSF

By Ron Cowen
PUBLISHED APRIL 11, 2017
WESTFORD, MASSACHUSETTS For the monster at the Milky Way’s heart, it’s a wrap.

After completing five nights of observations, today astronomers may finally have captured the first-ever image of the famous gravitational sinkhole known as a black hole.

More precisely, the hoped-for portrait is of a mysterious region that surrounds the black hole. Called the event horizon, this is the boundary beyond which nothing, not even light, can escape the object’s gargantuan grasp.

As the final observing run ended at 11:22 a.m. ET, team member Vincent Fish sat contentedly in his office at the MIT Haystack Observatory in Westford, Massachusetts. For the past week, Fish had been on call 24/7, sleeping fitfully with his cell phone next to him, the ringer set loud.

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Now we wait to see it.

FIONA MACDONALD 12 APR 2017

Scientists around the world have spent five sleepless nights staring into the abyss, and are hoping they've been rewarded with something that could change physics forever - the first photo of the event horizon at the edge of a black hole.

If their efforts were successful, we might be on the verge of actually seeing the edge of an elusive black hole, allowing us to see if the fundamentals of general relativity hold fast under some pretty extreme conditions. If Einstein was alive, we're sure he'd be excitedly freaking out right now.

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Commonly held belief and scientific proof holds true that black holes suck matter in rather than spewing them out. But NASA has just found some curious evidence around a supermassive black hole named Markarian 335.

Two of NASA’s telescopes, including the Nuclear Spectroscopic Telescope Array (NuSTAR), observed what is believed to be a black hole’s corona launching away from the supermassive black hole. That event was then followed by a large pulse of X-Ray energy.

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The EHT team has produced simulations of what Einstein's theories predict the hole should look like

Scientists believe they are on the verge of obtaining the first ever picture of a black hole.

By Jonathan Amos
BBC Science Correspondent, Boston

They have built an Earth-sized "virtual telescope" by linking a large array of radio receivers - from the South Pole, to Hawaii, to the Americas and Europe.

There is optimism that observations to be conducted during 5-14 April could finally deliver the long-sought prize.
In the sights of the so-called "Event Horizon Telescope" will be the monster black hole at the centre of our galaxy.
Although never seen directly, this object, catalogued as Sagittarius A*, has been determined to exist from the way it influences the orbits of nearby stars.

These race around a point in space at many thousands of km per second, suggesting the hole likely has a mass of about four million times that of the Sun.

But as colossal as that sounds, the "edge" of the black hole - the horizon inside which an immense gravity field traps all light - may be no more than 20 million km or so across.

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 LIGO Detection: Behind the scenes of the discovery of the decade

To celebrate the one-year anniversary of a discovery that changed the face of astronomy, on 7 February we feature the exclusive world premiere of a new documentary.

LIGO Detection reveals what unfolded behind the scenes between the detection of merging black holes on 14 September 2015, and five months later when LIGO announced it to the world

Click here to sign up to our newsletter and find out about exclusive content like this before anyone else.

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Following their discovery, the US White House Committee on Science, Space, and Technology asked LIGO Scientific Collaboration members to testify on the discovery, its meaning for science and society, and what the future may hold. From left to right: assistant director of the NSF's Directorate of Mathematical and Physical Sciences, Fleming Crim; LIGO lab director David Reitze; LIGO spokesperson Gabriela Gonzalez; and LIGO MIT director David Shoemaker. (Courtesy: LIGO Collaboration)

The Physics World 2016 Breakthrough of the Year goes to "the LIGO Scientific Collaboration for its revolutionary, first-ever direct observations of gravitational waves". Nine other achievements are highly commended and cover topics ranging from nuclear physics to material science and more.

Almost exactly 100 years after they were first postulated by Albert Einstein in his general theory of relativity, gravitational waves hit the headlines in 2016 as the US-based LIGO collaboration detected two separate gravitational-wave events using the Advanced Laser Interferometer Gravitational-wave Observatory (aLIGO). The first observation was made on 14 September 2015 and was announced in February this year. A second set of gravitational waves rolled through LIGO's detectors on 26 December 2015, and this so-called "Boxing Day event" was announced in June this year. Gravitational waves are ripples in the fabric of space–time, and these observations mark the end of a decades-long hunt for these interstellar undulations.

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Nicolle R. Fuller/Science Photo Library

Black hole mergers captured by LIGO offer a chance to explore new physics.

Gravitational-wave data show tentative signs of firewalls or other exotic physics.

Zeeya Merali
09 December 2016

It was hailed as an elegant confirmation of Einstein’s general theory of relativity — but ironically the discovery of gravitational waves earlier this year could herald the first evidence that the theory breaks down at the edge of black holes. Physicists have analysed the publicly released data from the Laser Interferometer Gravitational-Wave Observatory (LIGO), and claim to have found “echoes” of the waves that seem to contradict general relativity’s predictions1.

The echoes could yet disappear with more data. If they persist, the finding would be extraordinary. Physicists have predicted that Einstein’s hugely successful theory could break down in extreme scenarios, such as at the centre of black holes. The echoes would indicate the even more dramatic possibility that relativity fails at the black hole’s edge, far from its core.

If the echoes go away, then general relativity will have withstood a test of its power — previously, it wasn’t clear that physicists would be able to test their non-standard predictions.

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by Shane L. Larson

The seas of the Cosmos are vast and deep. From our vantage point here on the shores of Earth, we have seen much that is beautiful, awe-inspiring, frightening, humbling, confusing, and enigmatic. The simple truth of astronomy is that it is a spectator sport. The only thing we can do, is watch the skies and wait for the next Big Thing to happen. We collect events, like bottle-caps or flowers, and add them to our collection. Each new addition is a mystery, a new piece of a puzzle that takes shape ever-so-slowly over time.

On 14 September 2015, the LIGO-Virgo collaboration announced that they had detected the first gravitational waves ever, and that those waves had been created by a pair of merging black holes far across the Cosmos.

Today, we have some more news: LIGO has detected the second gravitational wave event ever, and those waves were also created by a pair of merging black holes far across the Cosmos. But as is often the case with astronomy, we know what we’ve observed, but we still don’t know what it means.

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This illustration represents the best evidence to date that the direct collapse of a gas cloud produced supermassive black holes in the early Universe. Researchers combined data from NASA’s Chandra, Hubble, and Spitzer telescopes to make this discovery.
Credits: NASA/CXC/STScI

Using data from NASA’s Great Observatories, astronomers have found the best evidence yet for cosmic seeds in the early universe that should grow into supermassive black holes.

Researchers combined data from NASA’s Chandra X-ray Observatory, Hubble Space Telescope, and Spitzer Space Telescope to identify these possible black hole seeds. They discuss their findings in a paper that will appear in an upcoming issue of the Monthly Notices of the Royal Astronomical Society.

“Our discovery, if confirmed, explains how these monster black holes were born,” said Fabio Pacucci of Scuola Normale Superiore (SNS) in Pisa, Italy, who led the study. “We found evidence that supermassive black hole seeds can form directly from the collapse of a giant gas cloud, skipping any intermediate steps.”

Scientists believe a supermassive black hole lies in the center of nearly all large galaxies, including our own Milky Way. They have found that some of these supermassive black holes, which contain millions or even billions of times the mass of the sun, formed less than a billion years after the start of the universe in the Big Bang.

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May 24, 2016

Dark matter is a mysterious substance composing most of the material universe, now widely thought to be some form of massive exotic particle. An intriguing alternative view is that dark matter is made of black holes formed during the first second of our universe's existence, known as primordial black holes. Now a scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, suggests that this interpretation aligns with our knowledge of cosmic infrared and X-ray background glows and may explain the unexpectedly high masses of merging black holes detected last year.

"This study is an effort to bring together a broad set of ideas and observations to test how well they fit, and the fit is surprisingly good," said Alexander Kashlinsky, an astrophysicist at NASA Goddard. "If this is correct, then all galaxies, including our own, are embedded within a vast sphere of black holes each about 30 times the sun's mass."

In 2005, Kashlinsky led a team of astronomers using NASA's Spitzer Space Telescope to explore the background glow of infrared light in one part of the sky. The researchers reported excessive patchiness in the glow and concluded it was likely caused by the aggregate light of the first sources to illuminate the universe more than 13 billion years ago. Follow-up studies confirmed that this cosmic infrared background (CIB) showed similar unexpected structure in other parts of the sky.

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To do so, they looked to a second black hole orbiting the first

By Caleb Scharf on May 1, 2016

Black holes may be massive, but they are also extraordinarily compact. That combination of properties makes them challenging regions to evaluate across vast cosmic distances. To learn more about these objects' physical properties, astronomers must therefore come up with measuring tricks. An international team of astronomers recently invented a new one: in the Astrophysical Journal Letters, the members report how to determine a black hole's spin using the interactions of two giant holes bound in mutual orbit.

OJ 287, a binary supermassive black hole system, sits about 3.5 billion light-years from Earth. The duo's primary black hole weighs in at an estimated 18 billion solar masses; the second is a mere 150 million solar masses. Because of this dramatic inequality in size, the smaller hole follows an orbit that punches through a disk of superheated matter swirling around the larger hole. These “outburst” events always occur within a 12-year orbit and are read by astronomers as changes in the system's visible light, which is for the most part produced by the superheated material.

Link of the article : http://arxiv.org/abs/1603.04171

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• Hawking's theory couldn't be proven, as it didn't relate effects of radiation
• Most believed impossible for information to hide while black hole shrunk
• Two separate groups of researchers have evidence to back up these claims
• These discoveries could help win the physicist the Nobel Prizε

For forty years ago, Stephen Hawking famously announced black holes evaporate and shrink because they emit radiation.
This so-called 'Hawking radiation' was a revolutionary theory, but due to the fragile nature of the escaping radiation, has been difficult to prove.

Now, two separate groups of researchers have discovered evidence to back up Hawking's claims - and their discoveries could finally help win the eminent physicist a Nobel Prize.

There has been a long standing belief that when a black hole dies, everything inside is destroyed.
Hawking's theory states that black holes should have the ability to thermally create and emit sub-atomic particles until they are completely depleted of their energy, known as Hawking radiation.

Read more: 

IN BRIEF

Scientists at Advanced LIGO believe they may be able to begin discerning as many as 2,000 faint echoes of black hole mergers within three years.

SEARCHING FOR MEANING IN A SEA OF NOISE

The long-awaited detection of gravitational waves was announced with a clear and unmistakable note—it was a “chirp” that noticeably rose above the welter of background noise. It was the swan song of two roughly 30-Solar-mass black holes coalescing into a single spacetime-warping monster some 1.3 billion light-years away.

But such chirps may be few and far between, and now scientists at the Advanced Laser Interferometer Gravitational-Wave Observatory (LIGO) think they may be able to discern the distant roar of multiple black hole mergers in that background noise.

The study, detailed in the April 1 issue of Physical Review Letters, predicts that scientists may be able to discover these ephemeral signals in as little as three years.

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Findings by University of Cape Town, University of Western Cape offer glimpse of early universe to be revealed when SKA is operational

By Alexis Haden - April 11, 2016

Deep radio imaging by researchers in the University of Cape Town and University of the Western Cape has revealed that supermassive black holes in a region of the distant universe are all spinning out radio jets in the same direction – most likely a result of primordial mass fluctuations in the early universe, a new paper in MNRAS reports today.

The new result is the discovery – for the first time – of an alignment of the jets of radio galaxies over a large volume of space, a finding made possible by a three-year deep radio imaging survey of the radio waves coming from a region called ELAIS-N1 using the Giant Metrewave Radio Telescope (GMRT).

The radio jets are produced by the supermassive black holes at the centres of these galaxies, and the only way for this alignment to exist is if supermassive black holes are all spinning in the same direction, says Prof Andrew Russ Taylor, joint UWC/UCT SKA Chair, Director of the recently-launched Inter-University Institute for Data Intensive Astronomy and principal-author of the study.

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(Phys.org)—The research team working with the LIGO project has proposed that the data gleaned from the discovery of gravity waves last year allows for calculating the likely level of cosmic background noise due to gravitational waves, and that it is much greater than previous models have suggested. In their paper published in Physical Review Letters, researchers with the LIGO Scientific Collaboration along with a companion group from the Virgo Collaboration, describe their reasoning behind their estimates and why they believe they will be able to offer more support for their theory within just a few years.

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06 April 2016

Astronomers have uncovered one of the biggest supermassive black holes, with the mass of 17 billion Suns, in an unlikely place: the centre of a galaxy that lies in a quiet backwater of the Universe. The observations, made with the NASA/ESA Hubble Space Telescope and the Gemini Telescope in Hawaii, indicate that these monster objects may be more common than once thought. The results of this study are released in the journal Nature.

Until now, the biggest supermassive black holes – those having more than 10 billion times the mass of our Sun – have only been found at the cores of very large galaxies in the centres of massive galaxy clusters. Now, an international team of astronomers using the NASA/ESA Hubble Space Telescope has discovered a supersized black hole with a mass of 17 billion Suns in the centre of the rather isolated galaxy NGC 1600.
NGC 1600 is an elliptical galaxy which is located not in a cluster of galaxies, but in a small group of about twenty. The group is located 200 million light-years away in the constellation Eridanus. While finding a gigantic supermassive black hole in a massive galaxy within a cluster of galaxies is to be expected, finding one in an average-sized galaxy group like the one surrounding NGC 1600 is much more surprising.
"Even though we already had hints that the galaxy might host an extreme object in the centre, we were surprised that the black hole in NGC 1600 is ten times more massive than predicted by the mass of the galaxy," explains lead author of the study Jens Thomas from the Max Planck-Institute for Extraterrestrial Physics, Germany.

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Artist’s impression of a quasar. In the quasar OJ 287, a secondary supermassive black hole orbits the primary, occasionally punching through the accretion disk surrounding the primary. [ESO/M. Kornmesser]

This past December, researchers all over the world watched an outburst from the enormous black hole in OJ 287 — an outburst that had been predicted years ago using the general theory of relativity.

Outbursts from Black-Hole Orbits

OJ 287 is one of the largest supermassive black holes known, weighing in at 18 billion solar masses. Located about 3.5 billion light-years away, this monster quasar is bright enough that it was first observed as early as the 1890s. What makes OJ 287 especially interesting, however, is that its light curve exhibits prominent outbursts roughly every 12 years.

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Paris, 16 March 2016
"A source accelerating Galactic cosmic rays to unprecedented energy discovered at the centre of the Milky Way"

For more than ten years the H.E.S.S. observatory in Namibia, run by an international collaboration of 42 institutions in 12 countries, has been mapping the centre of our galaxy in very-high-energy gamma rays. These gamma rays are produced by cosmic rays from the innermost region of the Galaxy. A detailed analysis of the latest H.E.S.S. data, published on 16th March 2016 in Nature, reveals for the first time a source of this cosmic radiation at energies never observed before in the Milky Way: the supermassive black hole at the centre of the Galaxy, likely to accelerate cosmic rays to energies 100 times larger than those achieved at the largest terrestrial particle accelerator, the LHC at CERN.

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The LIGO facility in Livingston, Louisiana, has a twin in Hanford, Washington   © ATMOSPHERE AERIAL

By Adrian ChoFeb. 5, 2016 , 2:30 PM

It's just a rumor, but if specificity is any measure of credibility, it might just be right. For weeks, gossip has spread around the Internet that researchers with the Laser Interferometer Gravitational-Wave Observatory (LIGO) have spotted gravitational waves—ripples in space itself set off by violent astrophysical events. In particular, rumor has it that LIGO physicists have seen two black holes spiraling into each other and merging. But now, an email message that ended up on Twitter adds some specific numbers to those rumors. The author says he got the details from people who have seen the manuscript of the LIGO paper that will describe the discovery.

"This is just from talking to people who said they've seen the paper, but I've not seen the paper itself," says Clifford Burgess, a theoretical physicist at McMaster University in Hamilton, Canada, and the Perimeter Institute for Theoretical Physics in nearby Waterloo. "I've been around a long time, so I've seen rumors come and go. This one seems more credible."

According to Burgess's email, which found its way onto Twitter as an image attached to a tweet from one of his colleagues, LIGO researchers have seen two black holes, of 29 and 36 solar masses, swirling together and merging. The statistical significance of the signal is supposedly very high, exceeding the "five-sigma" standard that physicists use to distinguish evidence strong enough to claim discovery. LIGO consists of two gargantuan optical instruments called interferometers, with which physicists look for the nearly infinitesimal stretching of space caused by a passing gravitational wave. According to Burgess's email, both detectors spotted the black hole merger with the right time delay between them.

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NASA, ESA, D. Coe, G. Bacon (STScI)
A black hole, visualized here in the M60-UCD1 galaxy, was thought to lose information as it disappears.

Some welcome his latest report as a fresh way to solve a black-hole conundrum; others are unsure of its merits.

Davide Castelvecchi
27 January 2016

Almost a month after Stephen Hawking and his colleagues posted a paper about black holes online1, physicists still cannot agree on what it means.

Some support the preprint’s claim — that it provides a promising way to tackle a conundrum known as the black hole information paradox, which Hawking identified more than 40 years ago. “I think there is a general sense of excitement that we have a new way of looking at things that may get us out of the logjam,” says Andrew Strominger, a physicist at Harvard University in Cambridge, Massachusetts, and a co-author of the latest paper.

Strominger presented the results on 18 January at a crowded talk at the University of Cambridge, UK, where Hawking is based.

Others are not so sure that the approach can solve the paradox, although some say that the work illuminates various problems in physics. In the mid-1970s, Hawking discovered that black holes are not truly black, and in fact emit some radiation2. According to quantum physics, pairs of particles must appear out of quantum fluctuations just outside the event horizon — the black hole’s point of no return. Some of these particles escape the pull of the black hole but take a portion of its mass with them, causing the black hole to slowly shrink and eventually disappear.

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Successful commissioning of GRAVITY at the VLTI
13 January 2016

Zooming in on black holes is the main mission for the newly installed instrument GRAVITY at ESO’s Very Large Telescope in Chile. During its first observations, GRAVITY successfully combined starlight using all four Auxiliary Telescopes. The large team of European astronomers and engineers, led by the Max Planck Institute for Extraterrestrial Physics in Garching, who designed and built GRAVITY, are thrilled with the performance. During these initial tests, the instrument has already achieved a number of notable firsts. This is the most powerful VLT Interferometer instrument yet installed.

The GRAVITY instrument combines the light from multiple telescopes to form a virtual telescope up to 200 metres across, using a technique called interferometry. This enables the astronomers to detect much finer detail in astronomical objects than is possible with a single telescope.

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An illustration of two black holes orbiting one another. The black hole in the center of the image is starved of gas by the black hole at the left, making the gas cloud of the black hole on the left brighter.ILLUSTRATION BY ZOLTAN HAIMAN, ADAPTED FROM FARRIS ET AL. 2014

By DENNIS OVERBYE
SEPTEMBER 16, 2015
The apocalypse is still on, apparently — at least in a galaxy about 3.5 billion light-years from here.

Last winter a team of Caltech astronomers reported that a pair of supermassive black holes appeared to be spiraling together toward a cataclysmic collision that could bring down the curtains in that galaxy.

The evidence was a rhythmic flickering from the galaxy’s nucleus, a quasar known as PG 1302-102, which Matthew Graham and his colleagues interpreted as the fatal mating dance of a pair of black holes with a total mass of more than a billion suns. Their merger, the astronomers calculated, could release as much energy as 100 million supernova explosions, mostly in the form of violent ripples in space-time known as gravitational waves that would blow the stars out of that hapless galaxy like leaves off a roof.

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ABOUT THIS IMAGE:
This artistic illustration is of a binary black hole found in the center of the nearest quasar host galaxy to Earth, Markarian 231. Like a pair of whirling skaters, the black-hole duo generates tremendous amounts of energy that makes the core of the host galaxy outshine the glow of the galaxy's population of billions of stars. Quasars have the most luminous cores of active galaxies and are often fueled by galaxy collisions.

Hubble observations of the ultraviolet light emitted from the nucleus of the galaxy were used to deduce the geometry of the disk, and astronomers were surprised to see light diminishing close to the central black hole. They deduced that a smaller companion black hole has cleared out a donut hole in the accretion disk, and the smaller black hole has its own mini-disk with an ultraviolet glow.

Astronomers using NASA's Hubble Space Telescope have found that Markarian 231 (Mrk 231), the nearest galaxy to Earth that hosts a quasar, is powered by two central black holes furiously whirling about each other.

The finding suggests that quasars — the brilliant cores of active galaxies — may commonly host two central supermassive black holes that fall into orbit about one another as a result of the merger between two galaxies. Like a pair of whirling skaters, the black-hole duo generates tremendous amounts of energy that makes the core of the host galaxy outshine the glow of the galaxy's population of billions of stars, which scientists then identify as quasars.

Scientists looked at Hubble archival observations of ultraviolet radiation emitted from the center of Mrk 231 to discover what they describe as "extreme and surprising properties."

If only one black hole were present in the center of the quasar, the whole accretion disk made of surrounding hot gas would glow in ultraviolet rays. Instead, the ultraviolet glow of the dusty disk abruptly drops off towards the center. This provides observational evidence that the disk has a big donut hole encircling the central black hole. The best explanation for the observational data, based on dynamical models, is that the center of the disk is carved out by the action of two black holes orbiting each other. The second, smaller black hole orbits in the inner edge of the accretion disk, and has its own mini-disk with an ultraviolet glow.

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RECORDED IN LIGHT A ring of light surrounds the boundary of a black hole in this artist illustration. Stephen Hawking theorizes that light on this boundary encodes information about everything that falls into the black hole.

Light sliding along the outside of a black hole is the key to understanding what’s inside, Stephen Hawking says.

The proposal from the world’s most famous living physicist, presented August 25 at a conference in Stockholm, is the latest attempt to explain what happens to information that falls into the abyss of a black hole. Losing that information would violate a key principle of quantum mechanics, leading to what’s known as the information paradox.

Hawking and two collaborators claim that the contents of a black hole are inventoried on a hologram on its boundary, the event horizon. Unlike previous descriptions of this hologram, the researchers say, their proposal lays out a specific mechanism for storing information that applies to every black hole in the universe. “This resolves the information paradox,” Hawking said in his presentation at the Hawking Radiation conference at the KTH Royal Institute of Technology.

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So I’m at this black hole conference in Stockholm, and at his public lecture yesterday evening, Stephen Hawking announced that he has figured out how information escapes from black holes, and he will tell us today at the conference at 11am.

As your blogger at location I feel a certain duty to leak information ;)

Extrapolating from the previous paper and some rumors, it’s something with AdS/CFT and work with Andrew Strominger, so likely to have some strings attached.

30 minutes to 11, and the press has arrived. They're clustering in my back, so they're going to watch me type away, fun.

10 minutes to 11, some more information emerges. There's a third person involved in this work, besides Andrew Strominger also Malcom Perry who is sitting in the row in front of me. They started their collaboration at a workshop in Hereforshire Easter 2015.

10 past 11. The Awaited is late. We're told it will be another 10 minutes.

11 past 11. Here he comes.

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Smoothed SDSS image of RGG 118, home of the smallest black hole ever observed in a galactic nucleus. The inset shows the Chandra identification of an x-ray source at the center. Credit: Baldassare et al. 2015
A team of astronomers have reported the detection of the smallest black hole (BH) ever observed in a galactic nucleus. The BH is hosted in the center of dwarf galaxy RGG 118, and it weighs in at 50,000 solar masses, according to observations made by Vivienne Baldassare of University of Michigan and her collaborators.

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Alternative gravity theories would result in “bumpy black holes,” which might be identifiable in x-ray observations.

Just before being gobbled up by a black hole, in-falling matter may emit an x-ray signal that could tell us about the black hole’s gravitational field. That’s the assumption of a new theoretical study of matter-accretion disks that form around black holes. The researchers show that alternative gravity models—characterized by “bumps” in the spacetime fabric around the black hole—produce slightly different x-ray emission from the disks. But identifying this signal will be challenging.

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Particle swarm. In Schnittman’s simulation, dark matter particles (shown with gray and pink trails) orbiting a rotating black hole (central sphere) could occasionally gain a large amount of energy and escape. The blue region (the ergosphere) is where the black hole’s rotation pulls spacetime along.

Particles orbiting near a spinning black hole might collide and get ejected with much more energy than previous calculations showed.

Black holes are mostly takers, not givers, but collisions among matter around a spinning black hole can result in high-energy particles that emerge with some of the black hole’s energy. Decades-old calculations showing only a modest energy gain for such particles are now contradicted by new results from two theoretical efforts showing that a particle can take away more than 10 times the energy that was put in. There are still questions about the feasibility of such collisions, but they might help astrophysicists understand some unexplained observations, such as an excess of gamma rays from the galactic center or ultrahigh-energy cosmic rays.

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• A clump of material has been jettisoned from a double star system at incredibly high speeds.
• X-rays from Chandra reveal that a pulsar in orbit around a massive star punched through a circumstellar disk of material.
• Three Chandra observations of the system were taken between December 2011 and February 2014.
• The data suggest the clump may even be accelerating due to the pulsar's powerful winds.

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In 2000, Betsy Weaver got hooked on a vision of things unseen.

As a student at Washington State University, Weaver’s physics program was visited by a group of scientists who lectured on the search into deep, deep, deep outer space. They spoke of phenomena mapped out by Albert Einstein, but so far undetected by humankind. Among these concepts, one stood out: Gravity waves.

Einstein’s math says they exist. Today’s astrophysicists agree. Gravity waves are transmitted from black holes and colliding neutron stars, neither of which has ever “seen” for real. Their existence could open the door to a new way of studying space, beyond optical and radio astronomy, because they can punch through astronomical obstacles that block light, noise and electro-magnetic waves.

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The LISA Pathfinder spacecraft is due to set off in autumn 2015 in a bid to prove that it is possible to observe gravitational waves in space. This is the latest step in an incredible journey to spot these ripples in spacetime that were first predicted by Albert Einstein 100 years ago.

If we can manage to capture these waves, then we should be able to observe some of the most violent events in the cosmos, such as black holes colliding and galaxies merging.

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Five billion years ago, a great disturbance rocked a region near the monster black hole at the center of galaxy 3C 279. On June 14, the pulse of high-energy light produced by this event finally arrived at Earth, setting off detectors aboard NASA's Fermi Gamma-ray Space Telescope and other satellites. Astronomers around the world turned instruments toward the galaxy to observe this brief but record-setting flare in greater detail.

"One day 3C 279 was just one of many active galaxies we see, and the next day it was the brightest thing in the gamma-ray sky," said Sara Cutini, a Fermi Large Area Telescope scientist at the Italian Space Agency's Science Data Center in Rome.

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The film Interstellar should be shown in school science lessons, a scientific journal has urged.
They say their call follows a new insight gained into black holes as a result of producing the visual effects for the Hollywood film.
Experts have also confirmed that the portrayal of "wormholes" is scientifically accurate.
Scientific papers have been published in the American Journal of Physics and in Classical and Quantum Gravity.

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Aiming to make the first portrait of the hungry monster at the center of our galaxy, astronomers built “a telescope as big as the world.”

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The supermassive black hole in NGC 5813 has erupted at least three times, with the latest still occurring.

Chandra data show the supermassive black hole at the center of NGC 5813 has erupted multiple times over 50 million years. NGC 5813 is the central component of a group of galaxies called the NGC 5813 Group that is immersed in an enormous reservoir of hot gas.

 Scientists discovered this history of black hole eruptions by studying the NGC 5813 Group, a group of galaxies about 105 million light-years from Earth. These Chandra observations are the longest ever obtained of a galaxy group, lasting for just over a week. The Chandra data are shown in this new composite image where the X-rays from Chandra (purple) have been combined with visible-light data (red, green, and blue).

Galaxy groups are like their larger cousins, galaxy clusters, but instead of containing hundreds or even thousands of galaxies like clusters do, galaxy groups are typically composed of 50 or fewer galaxies. Like galaxy clusters, groups of galaxies are enveloped by giant amounts of hot gas that emit X-rays.

The erupting supermassive black hole is located in the central galaxy of the NGC 5813 Group. The black hole’s spin, coupled with gas spiraling toward the black hole, can produce a rotating, tightly wound vertical tower of magnetic field that flings a large fraction of the inflowing gas away from the vicinity of the black hole in an energetic high-speed jet.

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Sharpest View Ever of Star Formation in the Distant Universe

ALMA’s Long Baseline Campaign has produced a spectacular image of a distant galaxy being gravitationally lensed. The image shows a magnified view of the galaxy’s star-forming regions, the likes of which have never been seen before at this level of detail in a galaxy so remote. The new observations are far sharper than those made using the NASA/ESA Hubble Space Telescope, and reveal star-forming clumps in the galaxy equivalent to giant versions of the Orion Nebula in the Milky Way.

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photo credit: An artist's conception of a black hole binary in a heart of a quasar, with the data showing the periodic variability superposed / Santiago Lombeyda/Caltech Center for Data-Driven Discovery

An unusual, repeating light signal in the distance may be coming from the final stages of a merger between two supermassive black holes. At just a few hundredths of a light-year apart, they could be merging in a mere one million years. An event like this has been predicted based on theory, but has never been observed before, according to a new study published in Nature this week.

The supermassive black holes at the center of most large galaxies (including ours) appear to co-evolve with their host galaxies: As galaxies merge, their black holes grow more massive too. Since we can’t actually see black holes, researchers look for their surrounding bands of material called accretion disks, which are produced by the intense pull of the black hole’s gravity. The disks of supermassive black holes can release vast amounts of heat, X-rays, and gamma rays that result in a quasar—one of the most luminous objects in the universe.

Caltech’s Matthew Graham and colleagues noticed the light signal coming from quasar PG 1302-102 while studying variability in quasar brightness using data from the Catalina Real-Time Transient Survey, which continuously monitored 500 million celestial light sources across 80 percent of the sky with three ground telescopes.

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 Black holes create and destroy galaxies, like this spiral galaxy in the constellation Dorado. (Roberto Colombari/Stocktrek Images/Corbis)

Much has been made of the mind-bending visual effects in Interstellar. But the methods created by the film’s Oscar-nominated visual effects team may have more serious applications than wowing movie audiences—they could actually be useful to scientists, too. A new paper in Classical and Quantum Gravity tells how the Interstellar team turned science fiction towards the service of scientific fact and produced a whole new picture of what it might look like to orbit around a spinning black hole.

Director Christopher Nolan and executive producer (and theoretical physicist) Kip Thorne wanted to create a visual experience that was immersive and credible. When they began to construct images of a black hole within an accretion disk, they realized that existing visual effects technology wouldn’t cut it—it created a flickering effect that would have looked bad in IMAX theaters. So the team turned to physics to create something different.

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