New research sheds light on black hole growth

Feb 14, 2013 by Tammy Plotner
The black hole that has grown the most can be found in the Sombrero galaxy . The researchers estimate that this black hole has been swallowing the equivalent of one Sun every twenty years and is now over 500 million times as heavy as the Sun. Credit: ESO Public Image Release

In a new study led by University of Central Lancashire astronomer Dr. Victor Debattista, researchers are looking into the mystery of how black holes grow and evolve. For many years, astronomers surmised black holes took on mass when their host galaxies merged, but now new modeling techniques show that black holes in spiral galaxies are forced to take on mass.

"Recent (HST) observations have revealed that a majority of (AGN) are resident in isolated disk , contrary to the usual expectation that AGN are triggered by mergers." says Debattista. "Here we develop a new test of the of (SMBHs) in disk galaxies by considering the local population of SMBHs. We show that substantial SMBH growth in spiral galaxies is required as disks assemble."

Weighing in a range of one million to one billion times that of the Sun, the located at the core of most galaxies would appear to be gaining at much quicker rates than expected. These are not just exceptions – more like rules. Even the 's quiescent black hole might be gaining as much mass as the Sun every 3,000 years. Past observations have shown growth during collision events, when huge amounts of gas around the black hole become intensely hot and shine as an active . This is a process which can be spotted as far back as the first formations in our Universe. However, these new simulations are giving insight into large scale growth without the need for violence.

"The X-ray-selected sample of moderate luminosity AGN consists of more than 50% disk galaxies, with ongoing mergers evident no more frequently than in nonactive galaxies." explains the research team. "Some show that even heavily obscured quasars are hosted largely by disks, not by mergers. Studies of star-formation using find that the specific star formation rates of X-ray selected AGN hosts are no different from those of inactive galaxies, also indicating that AGN hosts are not undergoing fundamentally different behaviors"

These modeling techniques, combined with current observations done with the Hubble Space Telescope, give credence to the theory that black holes can gain significant mass even in "quiet" spiral galaxies. As a matter of fact, there is a strong possibility that AGNs present in some spiral galaxies may even outnumber galaxy mergers. To make this concept even more exciting, astronomers are anticipating an event later this year in our own galaxy – an event where a gas cloud near the Milky Way's nucleus will encounter our own central black hole. According to predictions, our black hole may take on as much as 15 Earth masses in a period of 10 years from this cloud.

This concept of black hole growth isn't entirely new, though. According to other research done with the Hubble Space Telescope and led by Dr. Stelios Kazantzidis of Ohio State University and Professor Frank C. van den Bosch of Yale University, they had previously pinpointed mass properties of black holes – making size predictions which utilized the speed of stars residing in the galaxies. In this instance, the team disproved previous assumptions that black holes were unable to grow while the host galaxy grew. Their comparison of spiral and elliptical galaxies "found there is no mismatch between how big their black holes are." This means black holes would be gaining in mass – growing along at the same rate as the galaxy itself.

"These simulations show that it is no longer possible to argue that black holes in spiral galaxies do not grow efficiently. " comments Debattista on this new research. " Our simulations will allow us to refine our understanding of how black holes grew in different types of galaxies."

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Tuxford
1 / 5 (7) Feb 14, 2013
Big Bad Black Holes not caused by mergers??? Say it ain't so!

Hey, you can't say that I am surprised. More support for LaViolette. Eventually, you will all see the light!
omatwankr
1 / 5 (1) Feb 14, 2013
Finally something black holes don't do, conform to theory.
Tuxford
1 / 5 (4) Feb 14, 2013
"These simulations show that it is no longer possible to argue that black holes in spiral galaxies do not grow efficiently. "

That is because a spiral is a relatively mature galaxy, having grown up from the inside out. The source of the mass is from the mother core star, which has grown from within quite large by this stage. But this logic will require a somersault of thought. And science brains are lazy thinkers. They get too comfortable in their classifications and conclusions.

Can someone find a clear countervailing news item in the past couple of years for LaViolette's model??? I can't recall a single item. There are many items that remain inconclusive, subject to interpretation. And many items that clearly support his model. Yet lazy brains cling to their wonderful relativistic fantasy. Why? Has it really served astrophysics well?
katesisco
1 / 5 (3) Feb 15, 2013
As per MM paper (black holes and quasars) if density of the charge field exceeded gravity it would bounce all incoming energy. This is why large bh disassemble and their constituent star mass wanders off. After the loss of substantial star matter the bh regains its attraction and is drawn to local spirals making the spiral an elliptical.
yash17
2.8 / 5 (4) Feb 16, 2013
"For many years, astronomers surmised black holes took on mass when their host galaxies merged, but now new modeling techniques show that black holes in spiral galaxies are forced to take on mass."

I expect that black holes and supermassive black holes grow by all of these: endless supplied gas cloud (either poor or rich supply), colliding with other black holes and whatever matters or debris nearing them.
ValeriaT
1 / 5 (1) Feb 16, 2013
In AWT the process of large galaxy formation is similar to settling of shaked mixture of water and oil circulating inside of vessel. The central black holes are compacted during this and they lose their mass via radiation too. The huge black holes can be actually quite sparse objects in accordance to Schwarzschild criterion. The black holes at the center of Milky Way are poor quiet remnants of the original black holes which did span most of galaxy.
Fleetfoot
5 / 5 (2) Feb 16, 2013
That is because a spiral is a relatively mature galaxy, having grown up from the inside out. The source of the mass is from the mother core star, which has grown from within quite large by this stage.

Can someone find a clear countervailing news item in the past couple of years for LaViolette's model??? I can't recall a single item.


You are unlikely to find anything significant addressing such crank nonsense, over small regions like a galaxy, energy is conserved. Unless your crank can come up with evidence to the contrary, it will always be seen as nothing but pseudo-science.
ValeriaT
1 / 5 (1) Feb 16, 2013
over small regions like a galaxy, energy is conserved
The galaxies are losing lotta energy with radiation. My opinion is roughly the same: in steady state Universe model the galaxies are forming gradually at many places of the Universe with condensation of dark matter clouds until they nucleosynthesis gets ignited inside of them. Such a models are popular even in mainstream cosmology of recent era (search for gravastars and dark matter stars models for example).
Fleetfoot
5 / 5 (4) Feb 16, 2013
.. in steady state Universe model the galaxies are forming gradually at many places of the Universe with condensation of dark matter clouds until they nucleosynthesis gets ignited inside of them. Such a models are popular even in mainstream cosmology of recent era...


Nah, quasi-steady state was abandoned years ago even by those who proposed it. They tried a bounce version but that failed badly too.

Note also that you cannot get nucleosynthesis involving dark matter, it doesn't respond to the strong or EM forces.