TAT Blog

First Proof that "Plunging Regions" Exist Around Black Holes

2024-05-22T19:18:39+00:00

An image of NuSTAR overlaid on an artist's illustration of an accreting black hole. This paper provides the first observational proof of material in the so-called "plunging region", between the inner edge of the accretion disk and the event horizon of the black hole. Image credit: NASA/JPL-Caltech

May 16, 2024

Using X-ray data from NASA's NuSTAR and NICER satellites to test a key prediction of Einstein’s theory of gravity, an international team of astrophysicists have published the first observational proof that a “plunging region” around black holes not only exists, but exerts some of the strongest gravitational forces yet identified in the galaxy.

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A bizarre gamma-ray burst breaks the rules for these cosmic eruptions

2022-12-08T12:38:35+00:00

One possible origin for GRB 211211A, shown in this illustration, is a pair of compact stars merging (bright dots in the center) and emitting jets of radiation (green and purple beams). Heavy elements forming in the clouds of matter surrounding the stars emit light that is known as a kilonova. SAMUELE RONCHINI/GSSI 2022

By Lisa Grossman
8.12.2022

Astronomers have spotted a bright gamma-ray burst that upends previous theories of how these energetic cosmic eruptions occur.

For decades, astronomers thought that GRBs came in two flavors, long and short — that is, lasting longer than two seconds or winking out more quickly. Each type has been linked to different cosmic events. But about a year ago, two NASA space telescopes caught a short GRB in long GRB’s clothing: It lasted a long time but originated from a short GRB source.

“We had this black-and-white vision of the universe,” says astrophysicist Eleonora Troja of the Tor Vergata University of Rome. “This is the red flag that tells us, nope, it’s not. Surprise!”

This burst, called GRB 211211A, is the first that unambiguously breaks the binary, Troja and others report December 7 in five papers in Nature and Nature Astronomy.

Prior to the discovery of this burst, astronomers mostly thought that there were just two ways to produce a GRB. The collapse of a massive star just before it explodes in a supernova could make a long gamma-ray burst, lasting more than two seconds (SN: 10/28/22). Or a pair of dense stellar corpses called neutron stars could collide, merge and form a new black hole, releasing a short gamma-ray burst of two seconds or less.

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IceCube neutrinos give us first glimpse into the inner depths of an active galaxy

2022-11-03T23:20:58+00:00

Hubble image of the spiral galaxy NGC 1068. Credit: NASA/ESA/A. van der Hoeven

Posted on November 3, 2022 by Staff

The detection was made at the National Science Foundation-supported IceCube Neutrino Observatory, a massive neutrino telescope encompassing 1 billion tons of instrumented ice at depths of 1.5 to 2.5 kilometers below Antarctica’s surface near the South Pole. This unique telescope, which explores the farthest reaches of our universe using neutrinos, reported the first observation of a high-energy astrophysical neutrino source in 2018. The source, TXS 0506+056, is a known blazar located off the left shoulder of the Orion constellation and 4 billion light-years away.

“One neutrino can single out a source. But only an observation with multiple neutrinos will reveal the obscured core of the most energetic cosmic objects,” says Francis Halzen, a professor of physics at the University of Wisconsin–Madison and principal investigator of IceCube. He adds, “IceCube has accumulated some 80 neutrinos of teraelectronvolt energy from NGC 1068, which are not yet enough to answer all our questions, but they definitely are the next big step towards the realization of neutrino astronomy.”

Unlike light, neutrinos can escape in large numbers from extremely dense environments in the universe and reach Earth largely undisturbed by matter and the electromagnetic fields that permeate extragalactic space. Although scientists envisioned neutrino astronomy more than 60 years ago, the weak interaction of neutrinos with matter and radiation makes their detection extremely difficult. Neutrinos could be key to our queries about the workings of the most extreme objects in the cosmos.

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Emanuele Berti has received the 2023 Richard A. Isaacson Award in Gravitational-Wave Science

2022-10-15T08:34:24+00:00

Richard A. Isaacson Award in Gravitational-Wave Science

This award recognizes outstanding contributions in gravitational-wave physics, gravitational-wave astrophysics, and the technologies that enable this science.

The annual award consists of $5,000, a certificate, travel reimbursement and a registration waiver to attend the APS April Meeting to give an invited talk and accept the award.

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