Astronomers Discover Link Between Supermassive Black Holes and Galaxy Formation

physorg.com ^ | February 2nd, 2009 | National Science Foundation

[Ernest_at_the_Beach]

(PhysOrg.com) -- A pair of astronomers from Texas and Germany have used a telescope at The University of Texas at Austin's McDonald Observatory together with Hubble Space Telescope and many other telescopes around the world to uncover new evidence that the largest, most massive galaxies in the universe and the supermassive black holes at their hearts grew together over time.

"They evolved in lockstep," said The University of Texas at Austin's John Kormendy, who co-authored the research with Ralf Bender of Germany's Max-Planck-Institute for Extraterrestrial Physics and Ludwig Maximilians University Observatory. The results are puiblished in this week's issue of Astrophysical Journal Letters.

Astronomers know that galaxies, those vast cities of millions or billions of stars, grow larger through collisions and mergers. Kormendy and Bender's work involves the biggest galaxies in the universe--"elliptical galaxies" that are shaped roughly like footballs and that can be made of as many as a thousand billion stars. Virtually all of these galaxies contain a black hole at their centers, that is, an infinitely dense region that contains the mass of millions or billions of Suns and from which no light can escape.

A current leading theory says that when galaxies collide, their black holes end up revolving around each other. Together, the two black holes act like an egg beater: They violently stir up the galaxy center with their incredibly strong gravity, and they fling stars out of the central regions. As the black hole pair sinks to the center of the new merger remnant, this supergalaxy's core is depleted of the stars that were flung away. Kormendy and Bender measured the resulting dimming of such galaxies' cores, their so-called "light deficits."

[cripplecreek]

Black holes aren’t black, they’re photon impared.

[Ernest_at_the_Beach]

Related thread:

Black Holes Preceded Galaxies, Discovery Suggests

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Do these articles disagree?

[Tennessee_Bob]

Well, duh. I thought everyone knew this. We were just discussing this the other day here at the help desk.

[SunkenCiv]

Thanks Ernest_at_the_Beach.

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[samtheman]

I know that in the world of laymen there are “black hole skeptics”, those who doubt black holes even exist.

I’m not one of those.

But I do have a question regarding black holes at the centers of distant galaxies. How are they detected? What evidence to astronomers have for the assertion that every galaxy has a black hole at its center?

I’m not doubting. I just don’t know the answer.