NASA's Swift Survey finds 'Smoking Gun' of Black Hole Activa

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NASA's Swift Survey finds 'Smoking Gun' of Black Hole Activa

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Data from an ongoing survey by NASA's Swift satellite have helped astronomers solve a decades-long mystery about why a small percentage of black holes emit vast amounts of energy.

Only about one percent of supermassive black holes exhibit this behavior. The new findings confirm that black holes "light up" when galaxies collide, and the data may offer insight into the future behavior of the black hole in our own Milky Way galaxy. The study will appear in the June 20 issue of The Astrophysical Journal Letters.

The intense emission from galaxy centers, or nuclei, arises near a supermassive black hole containing between a million and a billion times the sun's mass. Giving off as much as 10 billion times the sun's energy, some of these active galactic nuclei (AGN) are the most luminous objects in the universe. They include quasars and blazars.

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The optical counterparts of many active galactic nuclei (circled) detected by the Swift BAT Hard X-ray Survey clearly show galaxies in the process of merging. These images, taken with the 2.1-meter telescope at Kitt Peak National Observatory in Arizona, show galaxy shapes that are either physically intertwined or distorted by the gravity of nearby neighbors. These AGN were known prior to the Swift survey, but Swift has found dozens of new ones in more distant galaxies. Credit: NASA/Swift/NOAO/Michael Koss and Richard Mushotzky (Univ. of Maryland

"Theorists have shown that the violence in galaxy mergers can feed a galaxy's central black hole," said Michael Koss, the study's lead author and a graduate student at the University of Maryland in College Park. "The study elegantly explains how the black holes switched on."

Until Swift's hard X-ray survey, astronomers never could be sure they had counted the majority of the AGN. Thick clouds of dust and gas surround the black hole in an active galaxy, which can block ultraviolet, optical and low-energy, or soft X-ray, light. Infrared radiation from warm dust near the black hole can pass through the material, but it can be confused with emissions from the galaxy's star-forming regions. Hard X-rays can help scientists directly detect the energetic black hole.

Since 2004, the Burst Alert Telescope (BAT) aboard Swift has been mapping the sky using hard X-rays.

"Building up its exposure year after year, the Swift BAT Hard X-ray Survey is the largest, most sensitive and complete census of the sky at these energies," said Neil Gehrels, Swift's principal investigator at NASA's Goddard Space Flight Center in Greenbelt, Md.

The survey, which is sensitive to AGN as far as 650 million light-years away, uncovered dozens of previously unrecognized systems.

"The Swift BAT survey is giving us a very different picture of AGN," Koss said. The team finds that about a quarter of the BAT galaxies are in mergers or close pairs. "Perhaps 60 percent of these galaxies will completely merge in the next billion years. We think we have the 'smoking gun' for merger-triggered AGN that theorists have predicted."

Other members of the study team include Richard Mushotzky and Sylvain Veilleux at the University of Maryland and Lisa Winter at the Center for Astrophysics and Space Astronomy at the University of Colorado in Boulder.

"We've never seen the onset of AGN activity so clearly," said Joel Bregman, an astronomer at the University Michigan, Ann Arbor, who was not involved in the study. "The Swift team must be identifying an early stage of the process with the Hard X-ray Survey."

Swift, launched in November 2004, is managed by Goddard. It was built and is being operated in collaboration with Penn State, the Los Alamos National Laboratory in New Mexico, and General Dynamics in Falls Church, Va.; the University of Leicester and Mullard Space Sciences Laboratory in the United Kingdom; Brera Observatory and the Italian Space Agency in Italy; plus additional partners in Germany and Japan.

This simulation follows the collision of two spiral galaxies that harbor giant black holes. The merger stirs up gas in both galaxies. Infalling gas "switches on" the black hole and creates an active galactic nucleus (AGN). Credit: Volker Springel and Tiziana Di Matteo (Max Planck Institute for Astrophysics), Lars Hernquist (Harvard Univ.)
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Re: NASA's Swift Survey finds 'Smoking Gun' of Black Hole Activa

Post by Mikey »

I'm curious as to why the phenomenon is so strictly confined to mergeing/colliding galaxies. One would think that any giant black hole would exhibit the same effect if enough gas were in its gravitic range.
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Re: NASA's Swift Survey finds 'Smoking Gun' of Black Hole Activa

Post by Tyyr »

But given the age of galaxies its possible that they've gobbled up everything in easy reach and switched off. What they get now isn't sufficient to make them active. When galaxies collide it disturbs the equilibrium and tosses lots of material the black hole's way. It might be that most galaxies have AGN when they're young but as everything settles out it turns off and only comes alive again when two galaxies collide.

And Blazar's, mmmmm.
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Re: NASA's Swift Survey finds 'Smoking Gun' of Black Hole Activa

Post by Mikey »

Good point, thanks.
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Re: NASA's Swift Survey finds 'Smoking Gun' of Black Hole Activa

Post by Sionnach Glic »

Always nice to see science answering some more mysteries...and then presenting us with yet more new questions.
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Re: NASA's Swift Survey finds 'Smoking Gun' of Black Hole Activa

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Isn't that its job? :)
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Re: NASA's Swift Survey finds 'Smoking Gun' of Black Hole Activa

Post by Tsukiyumi »

Sionnach Glic wrote:Always nice to see science answering some more mysteries...and then presenting us with yet more new questions.
Kinda like LOST. :lol:
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Re: NASA's Swift Survey finds 'Smoking Gun' of Black Hole Activa

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Mikey wrote:Isn't that its job? :)
Nah, it's job is to solve answers, creating new questions in need of answering is how it maintains job security.
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Re: NASA's Swift Survey finds 'Smoking Gun' of Black Hole Activa

Post by Mikey »

Lighthawk wrote:solve answers
Well, if you already have answers, what's there to solve? :P
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Re: NASA's Swift Survey finds 'Smoking Gun' of Black Hole Activa

Post by Lighthawk »

And science fails me again!
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Re: NASA's Swift Survey finds 'Smoking Gun' of Black Hole Activa

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That's why I only trust in brujeria.
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Re: NASA's Swift Survey finds 'Smoking Gun' of Black Hole Activa

Post by Teaos »

I read a paper awhile ago that says the MIlky Ways SMBH will turn intoa quasar when we crash into Andromeda.
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Re: NASA's Swift Survey finds 'Smoking Gun' of Black Hole Activa

Post by Sionnach Glic »

Mikey wrote:
Lighthawk wrote:solve answers
Well, if you already have answers, what's there to solve? :P
42? :wink:
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Re: NASA's Swift Survey finds 'Smoking Gun' of Black Hole Activa

Post by Mikey »

Of course. "What do you get when you multiply six by nine?" (I know, but there it is.)
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Re: NASA's Swift Survey finds 'Smoking Gun' of Black Hole Activa

Post by Sonic Glitch »

Mikey wrote:Of course. "What do you get when you multiply six by nine?" (I know, but there it is.)
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