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Posts Tagged ‘BLACK HOLES

Massive Black Hole Shreds Passing Star

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This artist’s rendering illustrates new findings about a star shredded by a black hole. When a star wanders too close to a black hole, intense tidal forces rip the star apart. In these events, called “tidal disruptions,” some of the stellar debris is flung outward at high speed while the rest falls toward the black hole. This causes a distinct X-ray flare that can last for a few years. NASA’s Chandra X-ray Observatory, Swift Gamma-ray Burst Explorer, and ESA/NASA’s XMM-Newton collected different pieces of this astronomical puzzle in a tidal disruption event called ASASSN-14li, which was found in an optical search by the All-Sky Automated Survey for Supernovae (ASAS-SN) in November 2014. The event occurred near a supermassive black hole estimated to weigh a few million times the mass of the sun in the center of PGC 043234, a galaxy that lies about 290 million light-years away. Astronomers hope to find more events like ASASSN-14li to test theoretical models about how black holes affect their environments.
During the tidal disruption event, filaments containing much of the star’s mass fall toward the black hole. Eventually these gaseous filaments merge into a smooth, hot disk glowing brightly in X-rays. As the disk forms, its central region heats up tremendously, which drives a flow of material, called a wind, away from the disk.
Read more at http://svs.gsfc.nasa.gov/cgi-bin/details.cgi?aid=12005

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October 22, 2015 at 5:44 pm

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Oxymoronic Black Hole Provides Clues to Growth

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A Sloan Digital Sky Survey image of RGG 118, a galaxy containing the smallest supermassive black hole ever detected. The inset is a Chandra image showing hot gas around the black hole. Credits: NASA/CXC/Univ of Michigan/V.F.Baldassare, et al; Optical: SDSS

A Sloan Digital Sky Survey image of RGG 118, a galaxy containing the smallest supermassive black hole ever detected. The inset is a Chandra image showing hot gas around the black hole.
Credits: NASA/CXC/Univ of Michigan/V.F.Baldassare, et al; Optical: SDSS

Astronomers using NASA’s Chandra X-ray Observatory and the 6.5-meter Clay Telescope in Chile have identified the smallest supermassive black hole ever detected in the center of a galaxy. This oxymoronic object could provide clues to how larger black holes formed along with their host galaxies 13 billion years or more in the past.

Astronomers estimate this supermassive black hole is about 50,000 times the mass of the sun. This is less than half the mass of the previous smallest black hole at the center of a galaxy. Read the rest of this entry »

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August 11, 2015 at 6:46 pm

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Flip-flopping black holes spin to the end of the dance

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When black holes tango, one massive partner spins head over heels (or in this case heels over head) until the merger is complete, said researchers at Rochester Institute of Technology in a paper published in Physical Review Letters.

This spin dynamic may affect the growth of black holes surrounded by accretion disks and alter galactic and supermassive binary black holes, leading to observational effects, according to RIT scientists Carlos Lousto and James Healy.

The authors of the study will present their findings at the American Physical Society meeting in Baltimore on April 14 and celebration of the Centennial of General Relativity.

Lousto and Healy, postdoctoral researcher at RIT, use sophisticated numerical techniques to solve Einstein’s equations of gravity and simulate black hole interactions on supercomputers. The specialized field known as numerical relativity grew from the general theory of relativity, first published in November 1915.

“We study binary spinning black holes to display the long-term individual spin dynamics,” said Lousto, professor in RIT’s School of Mathematical Sciences and a member of the Center for Computational Relativity and Gravitation.

In their paper, “Flip-flopping binary black holes,” Lousto and Healy numerically simulated equal-mass black holes and studied the individual alignment and direction of spin as the black holes approached merger. The binary black holes flirted for nearly 48 orbits, three precession cycles, and half of a flip-flop cycle.

“Lousto and Healy’s simulation is one of the longest ever attempted for spinning black hole binaries,” said Pedro Marronetti, National Science Foundation physics division program director. “Their results and potential observational effects will impact research in a wide range of areas, from gravitational physics to galactic evolution and cosmology.”

Key to their findings is that one black hole in the simulation totally changes the orientation of its spin. Its initial alignment with the orbital angular momentum changes to a complete anti-alignment after half of a flip-flop cycle, Lousto said.

The researchers compared this evolution with post-Newtonian equations of motion and spin evolution and deciphered maximum flip-flop angles and frequencies.

“We show that this process continuously flip-flops the spin during the lifetime of the binary until merger,” Lousto said.

Lousto and Healy visualized the black holes’ flip-flopping tango in a short animation. The mini-movie, produced at the Black Hole Lab in RIT’s Center for Computational Relativity and Gravitation, is set to Invierno Porteño by Argentine tango composer Ástor Piazzolla.

To watch a brief video about the Center for Computational Relativity at RIT, go to http://bit.ly/RITCCRG.

by Susan Gawlowicz – http://www.rit.edu/news/story.php?id=51746

Written by physicsgg

April 9, 2015 at 8:03 pm

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Black holes: Their large interiors

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Ingemar Bengtsson, Emma Jakobsson
Christodoulou and Rovelli have remarked on the large interiors possessed by static black holes. We amplify their remarks, and extend them to the spinning case.
Read more at http://arxiv.org/pdf/1502.01907v1.pdf

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February 9, 2015 at 6:54 pm

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What would a binary black hole merger look like?

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A pair of black holes that are about to merge, with the Milky Way visible in the background.

A pair of black holes that are about to merge, with the Milky Way visible in the background.

Andy Bohn, Francois Hebert, William Throwe, Darius Bunandar, Katherine Henriksson, Mark A. Scheel, Nicholas W. Taylor
We present a method of calculating the strong-field gravitational lensing caused by many analytic and numerical spacetimes.
We use this procedure to calculate the distortion caused by isolated black holes and by numerically evolved black hole binaries.
We produce both demonstrative images illustrating details of the spatial distortion and realistic images of collections of stars taking both lensing amplification and redshift into account.
On large scales the lensing from inspiraling binaries resembles that of single black holes, but on small scales the resulting images show complex and in some cases self-similar structure across different angular scales….
… read more at http://arxiv.org/pdf/1410.7775v1.pdf

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November 3, 2014 at 9:00 pm

Posted in ASTROPHYSICS, COSMOLOGY, RELATIVITY

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Big Black Holes Can Block New Stars

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Elliptical galaxy NGC 1132, as seen by NASA’s Chandra X-Ray Observatory; the blue/purple in the image is the X-ray glow from hot, diffuse gas that is not forming into stars. (Credit: NASA, ESA, M. West (ESO, Chile), and CXC/Penn State University/G. Garmire, et al.

Elliptical galaxy NGC 1132, as seen by NASA’s Chandra X-Ray Observatory; the blue/purple in the image is the X-ray glow from hot, diffuse gas that is not forming into stars. (Credit: NASA, ESA, M. West (ESO, Chile), and CXC/Penn State University/G. Garmire, et al.

Massive black holes spewing out radio-frequency-emitting particles at near-light speed can block formation of new stars in aging galaxies, a study has found.
The research provides crucial new evidence that it is these jets of “radio-frequency feedback” streaming from mature galaxies’ central black holes that prevent hot free gas from cooling and collapsing into baby stars. Read the rest of this entry »

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October 23, 2014 at 1:39 pm

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Researcher shows that black holes do not exist

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Read also: A surge of attacks against classical GR

Black holes have long captured the public imagination and been the subject of popular culture, from Star Trek to Hollywood. They are the ultimate unknown – the blackest and most dense objects in the universe that do not even let light escape. And as if they weren’t bizarre enough to begin with, now add this to the mix: they don’t exist.
By merging two seemingly conflicting theories, Laura Mersini-Houghton, a physics professor at UNC-Chapel Hill in the College of Arts and Sciences, has proven, mathematically, that black holes can never come into being in the first place. The work not only forces scientists to reimagine the fabric of space-time, but also rethink the origins of the universe.
“I’m still not over the shock,” said Mersini-Houghton. “We’ve been studying this problem for a more than 50 years and this solution gives us a lot to think about.”
For decades, black holes were thought to form when a massive star collapses under its own gravity to a single point in space – imagine the Earth being squished into a ball the size of a peanut – called a singularity. So the story went, an invisible membrane known as the event horizon surrounds the singularity and crossing this horizon means that you could never cross back. It’s the point where a black hole’s gravitational pull is so strong that nothing can escape it. Read the rest of this entry »

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September 24, 2014 at 2:06 pm

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Hubble Helps Find Smallest Known Galaxy Containing a Supermassive Black Hole

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M60_Astronomers using data from NASA’s Hubble Space Telescope and ground observation have found an unlikely object in an improbable place — a monster black hole lurking inside one of the tiniest galaxies ever known.

The black hole is five times the mass of the one at the center of our Milky Way galaxy. It is inside one of the densest galaxies known to date — the M60-UCD1 dwarf galaxy that crams 140 million stars within a diameter of about 300 light-years, which is only 1/500th of our galaxy’s diameter.

If you lived inside this dwarf galaxy, the night sky would dazzle with at least 1 million stars visible to the naked eye. Our nighttime sky as seen from Earth’s surface shows 4,000 stars.

The finding implies there are many other compact galaxies in the universe that contain supermassive black holes. The observation also suggests dwarf galaxies may actually be the stripped remnants of larger galaxies that were torn apart during collisions with other galaxies rather than small islands of stars born in isolation.

“We don’t know of any other way you could make a black hole so big in an object this small,” said University of Utah astronomer Anil Seth, lead author of an international study of the dwarf galaxy published in Thursday’s issue of the journal Nature. Read the rest of this entry »

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September 17, 2014 at 8:22 pm

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