Results 1 to 8 of 8

Thread: Ultra Massive Black holes & Dark Matter

  1. #1
    Join Date
    Jul 2019
    Posts
    1

    Ultra Massive Black holes & Dark Matter

    I was watching "How The Universe Works" that was about ultra massive black holes that are upwards of 10 billion solar masses. They explain the problem seems to be that there has not been enough time since the start of the expansion of the universe for these Ultra Massive Black Holes (UMBH) to have grown to the size they have become. One theory is that there could have been huge clouds of Hydrogen gas that could have skipped the star forming stage in what is called direct collapse. They go on to say that even with direct collapse they have found a few UMBHs in the estimated range of 15-20 billion solar masses which pushes the limits of the theory. I am curious if anyone knows if there is a publication considering dark matter as a way for these UMBHs to get to these sizes? I understand that dark matter is called dark because of our lack of knowledge and understanding of how it interacts (if it exists) with other matter. Gravity seems to be the way that dark matter helps holds our galaxies together. Is it a crazy idea to think that black holes, a place where our understanding of gravity is very weak, may also be collecting dark matter which may be causing the unexpected size of these UMBHs? Since we currently do not have a way of viewing or detecting dark matter may we be missing other things that are pulled into the black holes?

  2. #2
    Join Date
    Mar 2008
    Posts
    668
    A possible consideration of a connection between SMBH and DM is to look at evolution of surface density as the galactic core acquires gas in the early stages. When surface density falls below a critical value, the DM effect comes into play causing flat rotation curves. However as gas accrues into the core, the surface density begins to rise and when it rises above the critical value, the DM effect begins to disappear leaving only the Kepler rotation. The central gas. upon losing the acceleration will fly out of the center and ram into outer gas still dominated temporarily by the DM effect. Eventually the surface density of this sphere could exceed a critical value and close the surface. In effect this would form a Black Sphere. It would be difficult to access knowledge that could distinguish between a SMBH from a SMBS. This could alleviate the time formation problem and address the mass relation of 0.2% between the galaxy and the SMBH.

  3. #3
    Join Date
    Mar 2010
    Location
    United Kingdom
    Posts
    7,324
    Dark matter is called dark matter mostly because it cannot interact electromagnetically if you want it to behave as we have constrained it to. Because of this it is very hard to see how it can contribute significantly to the growth of black holes as it condenses at a much slower rate than baryonic matter. Essentially the only way to get it to contribute significantly is to add in an arbitrary tuning factor that says "behave this way near primordial black holes but not modern ones or other forms of matter".

  4. #4
    Join Date
    Aug 2008
    Location
    Wellington, New Zealand
    Posts
    4,437
    This article, Where Do Supermassive Black Holes Come From? has a dark matter related theory
    There are many other theories for how direct-collapse black holes could be created: Perhaps halos of dark matter formed ultramassive quasi-stars that then collapsed, or dense clusters of regular mass stars merged and then collapsed.

  5. #5
    Join Date
    Aug 2003
    Location
    The Wild West
    Posts
    9,506
    Quote Originally Posted by HugoStiglitz559 View Post
    ....the problem seems to be that there has not been enough time since the start of the expansion of the universe for these Ultra Massive Black Holes (UMBH) to have grown to the size they have become.....
    This 2009 paper "show[s] that there are three strong lines of argument that predicate the existence of UMBHs..."
    Everyone is entitled to his own opinion, but not his own facts.

  6. #6
    Join Date
    Mar 2008
    Posts
    668
    A paper today that has some bearing on the topic:
    Gravitational Collapse of Baryonic and Dark matter
    https://arxiv.org/abs/1907.12738
    Like stated earlier from the dark matter particle perspective, baryons are moire dynamic and able to collapse into the smaller SMBH structures where DM may collapse into larger halos. They look at modifications of the usual top hat collapse model using GR in place of Newton.

  7. #7
    Join Date
    Sep 2004
    Location
    South Carolina
    Posts
    5,019
    This 2018 paper is 22 pages long in PDF. On page 14 are three possible explanations for how ultramassive black holes of greater than ten billion solar masses could be created.

    I do not understand any of the three explanations, but perhaps someone else will.

    PDF https://arxiv.org/ftp/arxiv/papers/1710/1710.10268.pdf

    Abstract https://arxiv.org/abs/1710.10268

    The most massive black holes on the Fundamental Plane of Black Hole Accretion
    M. Mezcua, J. Hlavacek-Larrondo, J.R. Lucey, M. T. Hogan, A.C. Edge, B.R. McNamara (Submitted on 27 Oct 2017 (v1), last revised 6 Nov 2017 (this version, v2))

    We perform a detailed study of the location of brightest cluster galaxies (BCGs) on the fundamental plane of black hole (BH) accretion, which is an empirical correlation between a BH X-ray and radio luminosity and mass supported by theoretical models of accretion. The sample comprises 72 BCGs out to z∼0.3 and with reliable nuclear X-ray and radio luminosities. ... [math skipped] ... For BCGs to on average follow the fundamental plane, a large fraction (∼40%) should have BH masses > 10^10 M⊙ and thus host ultramassive BHs. The local BH-galaxy scaling relations would not hold for these extreme objects. The possible explanations for their formation, either via a two-phase process (the BH formed first, the galaxy grows later) or as descendants of high-z seed BHs, challenge the current paradigm of a synchronized galaxy-BH growth.
    Do good work. —Virgil Ivan "Gus" Grissom

  8. #8
    Join Date
    Sep 2004
    Location
    South Carolina
    Posts
    5,019
    2019 paper with a discussion of the creation of ultramassive ("overly massive") black holes that I do understand.

    abstract https://arxiv.org/abs/1903.09965
    pdf https://arxiv.org/pdf/1903.09965.pdf

    Expanding the Sample: The Relationship Between the Black Hole Mass of BCGs and the Total Mass of Galaxy Clusters
    Frederika Phipps, et al. (Submitted on 24 Mar 2019)

    "We speculate that the overly massive BHs in BCGs may be due to frequent mergers and cool gas inflows onto the cluster center."
    Do good work. —Virgil Ivan "Gus" Grissom

Tags for this Thread

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •