LISA Pathfinder operating in space

24 February 2016

On Monday, the two cubes housed in the core of ESA’s LISA Pathfinder were left to move under the effect of gravity alone – another milestone towards demonstrating technologies to observe gravitational waves from space.

It has been an intense couple of months for LISA Pathfinder. After launch on 3 December and six burns to raise the orbit, it finally reached its work site – 1.5 million km from Earth towards the Sun – in January, and the team of engineers and scientists started to switch on and test its systems.

One of the most delicate operations entailed releasing the two test masses from the mechanisms that kept them in place during ground handling, launch and cruise.

See full texthttp://www.esa.int/Our_Activities/Space_Science/Freefall_achieved_on_LISA_Pathfinder

Mission paves the way for planned €1-billion space observatory.

Elizabeth Gibney
25 February 2016

Scientists have long dreamed of launching a constellation of detectors into space to detect gravitational waves – ripples in space-time first predicted by Albert Einstein and observed for the first time earlier this month.

That dream is now a step closer to reality. Researchers working on a €400 million (US$440 million) mission to try out the necessary technology in space for the first time – involving firing lasers between metal cubes in freefall – have told Nature that the initial test-drive is performing just as well as they had hoped.

“I think we can now say that the principle has worked,” says Paul McNamara, project scientist for the LISA Pathfinder mission, which launched in December. “We believe that we now are in a good shape to look to the future and look to the next generation.”

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The Australia Telescope Compact Array, in New South Wales, which helped to identify the location of a fast radio burst.

For the first time, astronomers have traced an enigmatic blast of radio waves to its source.

Mark Zastrow
24 February 2016 Corrected: 25 February 2016

Since 2007, astronomers have detected curious bright blasts of radio waves from the cosmos, each lasting no more than a few milliseconds. Now scientists have been able to pinpoint the source of one of these pulses: a galaxy 1.9 billion parsecs (6 billion light years) away. It probably came from two colliding neutron stars, says astronomer Evan Keane, a project scientist for the Square Kilometre Array (SKA). Keane, who works at the SKA Organization's headquarters at Jodrell Bank Observatory outside Manchester, UK, led the team that reports the detection in Nature1.

The discovery is the “measurement the field has been waiting for”, says astronomer Kiyoshi Masui of the University of British Columbia in Vancouver, Canada. By finding more such fast radio bursts (FRBs) and measuring the distance to their source, astronomers hope to use the signals as beacons to shed light on the evolution of the Universe.

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                     Jim West/Alamy
The Green Bank Telescope in West Virginia is the third facility to have detected a fast radio burst.

American telescope detects clue to source of fast radio bursts.

Elizabeth Gibney
02 December 2015

For the past eight years, astronomers have been mystified by sudden, very short blasts of radio waves that defy explanation.

Now the most detailed study so far1 has furnished a clue to the origin of at least one of these strange pulses, or 'fast radio bursts' (FRBs). It came from a dense, magnetized region of space, and was probably emitted by a young neutron star (a compact core left in the aftermath of a supernova), says study author Kiyoshi Masui at the University of British Columbia in Canada.

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A simulated view of gravitational waves rippling out from merging black holes. The reddish waves correspond to those recently detected from a real black-hole merger by the Laser Interferometer Gravitational-wave Observatory (LIGO).
Credit: NASA/C. Henze

The Future of Gravitational Wave Astronomy
Fully opening this new window on the universe will take decades—even centuries
By Lee Billings on February 12, 2016

A century ago, when Albert Einstein first predicted the existence of gravitational waves—subtle ripples in spacetime produced by massive objects hurtling through the cosmos—he also guessed they could not ever be seen. Though the echoes of distant celestial symphonies must ripple through the very fabric of reality, Einstein thought their ethereal harmonies were destined to remain eternally unheard.

On Thursday, scientists using the Laser Interferometer Gravitational-wave Observatory (LIGO) proved Einstein both right and wrong, announcing their detection of the first note in a cosmic symphony he predicted no one would ever hear. It was a burbling chirp of gravitational waves produced by the cataclysmic birth of a black hole from the merger of two smaller ones. Emitted in a distant galaxy when multicellular life was just beginning to populate the Earth, the waves traveled at the speed of light for more than a billion years to at last wash over our planet last September, taking just seven milliseconds to traverse the distance between LIGO’s twin listening stations in Louisiana and Washington State.

Now, unlike Einstein a century ago who could scarcely imagine gravitational waves ever being seen, the scientists hunting the elusive spacetime ripples already have big plans for more detectors and observatories in the near and far future.
“Imagine light having never been collected in a photograph,” says Janna Levin, an astrophysicist at Barnard College of Columbia University and author of a forthcoming book about LIGO. “The first thing people want to do is just to capture the recording, which is what LIGO has done.”

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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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Gamma ray picture of the Milky Way, as seen by the NASA Fermi satellite. Inserts: two independent statistical analyses showed that the distribution of photons is clumpy rather than smooth, indicating that the excess gamma rays from the center of our galaxy are unlikely to be caused by dark matter annihilation.
Image courtesy of Christoph Weniger, UvA , © UvA/Princeton

The excess of gamma rays from the center of the Milky Way probably originates from rapidly rotating neutron stars and not from dark matter annihilation as previously claimed.

he puzzling excess of gamma rays from the center of the Milky Way probably originates from rapidly rotating neutron stars, or millisecond pulsars, and not from dark matter annihilation, as previously claimed. This is the conclusion of new data analyses by two independent research teams from the University of Amsterdam (UvA), Netherlands, and Princeton University/Massachusetts Institute of Technology (MIT).

In 2009, observations with the Fermi Large Area Telescope revealed an excess of high-energy photons, or gamma rays, at the center of our galaxy. It was long speculated that this gamma ray excess could be a signal of dark matter annihilation. If true, it would constitute a breakthrough in fundamental physics and a major step forward in our understanding of the matter constituents of the universe.

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The 4km "west" arm of the LIGO interferometer stretches into the foggy distance.

Ars goes inside ground zero of the search for gravitational waves.

by Eric Berger - Feb 4, 2016 2:00pm CET

LIVINGSTON, La.—The rain began to fall as Joe Giaime and I scrambled down a lonely rise, back toward the observatory’s main building. It wasn’t so much rain as a hard mist, characteristic of the muggy weather southern Louisiana often sees in January when moisture rolls inland from the Gulf of Mexico. As gray clouds fell like a shroud over the loblolly pines all around us, Giaime mused, “Well, I guess you’ve already gathered that we’re in the middle of nowhere."

Middle of nowhere happens to be ground zero in the search for gravitational waves, which were first posited by Albert Einstein a century ago and may soon become one of the hottest fields in science. Livingston is remote in terms of geography, but as humans scan the heavens for gravitational waves this forest is practically the center of the physics universe.

Because of general relativity, we understand that large masses curve spacetime, kind of like standing in the middle of a trampoline distorts the fabric. When massive, dense objects in space accelerate, such as black holes or neutron stars, they create ripples in the fabric of spacetime. These ripples carry gravitational radiation away from the very massive objects, and the radiation then propagates through the Universe. This Louisiana observatory, the Laser Interferometer Gravitational-Wave Observatory or LIGO, exists to try to measure these subtle ripples.

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Artist's concept of a millisecond pulsar. Credit: NASA

January 26, 2016 by Tomasz Nowakowski

(Phys.org)—NASA's Fermi Gamma-ray Space Telescope has once again proven that it is an excellent tool to search for rotating neutron stars emitting beams of electromagnetic radiation, known as pulsars. A team of astronomers, led by H. Thankful Cromartie of the University of Virginia, has recently used the 305-meter Arecibo radio telescope in Puerto Rico to observe unidentified sources of gamma rays detected by the Large Area Telescope (LAT) onboard the Fermi spacecraft. As it turns out, six of these objects indicated by LAT are rapidly rotating neutron stars, with periods of a few thousandths of a second, called millisecond pulsars (MSPs). The scientists published their results online on Jan. 20 on the arXiv pre-print server.

The objects of the study were chosen from the LAT's 4-year point source catalog. The astronomers chose 34 from over 1,000 unidentified sources of gamma rays to observe them in detail with the Arecibo telescope. The catalog provided crucial spectral data that helped distinguish possible MSPs from other gamma-ray-emitting objects, like active galactic nuclei (AGNs).

"Overall, the search for MSPs in the galactic disk has been made extremely efficient by employing Fermi-LAT data in selecting radio search targets," the researchers noted in their paper posted on arXiv.

Arecibo observations were conducted from June to September 2013. The telescope's raw sensitivity and its large gain makes it a very efficient tool for finding millisecond pulsars. Thanks to Arecibo, the researchers were able to detect six MSPs with rotation periods ranging between 1.99 and 4.66 ms. One of the newly detected pulsars is a typical neutron star, a white dwarf binary with an 83-day orbital period. According to the research, the other MSPs are in interacting compact binaries wit orbital period less than eight hours.

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Recent discoveries provided more decisive evidence for the magnetic structure of matter

Posted by The Watcher on January 24, 2016

Since the beginning of the space age, many observations sharply contradict the theories of a gravity-dominated Cosmos, yet recent observations have created even larger holes in those theories. Now it is impossible to cover these holes with any theoretical solution, such as the so-called red giants.

According to the consensus model, a star becomes a red giant in the later part of its life. In this stage, most of the fuel powering nuclear fusion in the core of the star is exhausted. As a result of this deficiency, "gravitational collapse" is induced. In other words, the star would collapse on itself due to a lack of light pressure which is pushing out against the force of gravity.

When this self-collapse takes place, it heats up a shell of hydrogen that surrounds the core. That heat would be sufficient to reignite fusion reaction, causing the star to become bigger as a result of increased light pressure and this process would make the star 1 000-10 000 times more luminous.

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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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Christian Krueger (right), IceCube/NSF

Week 1 at the Pole
By Jean DeMerit, 22 Jan 2016 10:30 AM

… now you don’t. These two photos show the spot of the geographical South Pole, just before and after the old marker was removed—as we mentioned last week, at the beginning of each year a new marker is situated at the current location, which shifts constantly due to the movement of the ice sheet. This year’s marker, which can be seen below, is about 10 meters away from the old spot (here's a close-up view).
Inside, they were busy last week packing data disks for shipment north—a lot of disks, in a lot of boxes. IceCube’s winterovers are standing next to their completed tower of boxes, which altogether contains every bit of data collected by IceCube for 2015. Off it goes.
Outside, there was some interesting work in the area of ice studies. Two deep holes were dug, separated by about half a meter (bottom images). One hole is open and receives full sunlight, the other has a plywood cover. The last image shows the view of the backlit wall of the open hole from inside the closed hole, with visible lines delineating snow and ice accumulation over time. The bright lines indicate summer seasons, when the new snow is compacted from the heat of the Sun.

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by Shane L. Larson

Each morning, I roll out of bed, dutifully feed the three cats that own me, help my fourth-grader get her backpack put together for the day and put my daily secret note in her lunch, enjoy a few brief moments over morning coffee with my spouse, and then it is off to work.

For my day job, I’m a scientist. My friends and I work in a completely new branch of astronomy called gravitational wave astronomy. Our express goal is to detect a phenomenon that was predicted almost a century ago by Einstein: the undulations and propagating ripples in the fabric of spacetime that signify the dynamic motion of matter in the Cosmos.

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The artist’s impression above shows what it would look like from an exoplanet 10,000 light-years away in its home galaxy.

By Daniel Clery

Jan. 14, 2016

Kaboom! Astronomers have found the most violently explosive supernova so far detected in the history of the universe. Supernovae are already some of the brightest events out there but in recent decades astronomers have seen a rare new class of blasts, superluminous supernovae (SLSNe)—sometimes dubbed hypernovae. The new discovery was spotted last June by the All Sky Automated Survey for SuperNovae (ASAS-SN), a system of eight small 14-centimeter telescopes at two sites in Chile and Hawaii that can scan the entire sky every 2 to 3 days. At its peak, ASAS-SN-15lh, as the new supernova is known, was twice as luminous as any previously seen, thousands of times brighter than a normal supernova, and outshone our entire Milky Way galaxy by 50 times. 

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14 January 2016

On 12 January 2016, the Japan Aerospace Exploration Agency (JAXA) presented their ASTRO-H satellite to the media at the Tanegashima Space Center, situated on a small island in the south of Japan. The satellite, developed with institutions in Japan, the US, Canada and Europe, is now ready to be mounted on an H-IIA rocket for launch on 12 February.

ASTRO-H is a new-generation satellite, designed to study some of the most powerful phenomena in the Universe by probing the sky in the X-ray and gamma-ray portions of the electromagnetic spectrum. Scientists will investigate extreme cosmic environments ranging from supernova explosions to supermassive black holes at the centres of distant galaxies, and the hot plasma permeating huge clusters of galaxies.

ESA contributed to ASTRO-H by partly funding various elements of the four science instruments, by providing three European scientists to serve as science advisors and by contributing one scientist to the team in Japan. In return for ESA’s contribution, European scientists will have access to the mission’s data.

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