Colliding Galaxies Created the First Black Holes


How were the Universe’s first supermassive black holes formed? A new model of the evolution of galaxies and black holes show collisions show that colliding galaxies likely spawned black holes that formed about 13 billion years ago. The discovery fills in a missing chapter of our universe’s early history, and could help write the next chapter — in which scientists better understand how gravity and dark matter formed the universe as we know it.

Following the recent discovery that galaxies formed much earlier in the Universe’s history than previously thought, Stelios Kazantzidis from The Ohio State University and his team created new computer simulations that show the first-ever super-massive black holes were likely born when those early galaxies collided and merged together. This likely happened during the first few billion years after the Big Bang.

“Our results add a new milestone to the important realization of how structure forms in the universe,” Kazantzidis said.

Previously, astronomers thought galaxies evolved hierarchically, where gravity drew small bits of matter together first, and those small bits gradually came together to form larger structures.

But the the new models turn that notion on its head.

“Together with these other discoveries, our result shows that big structures — both galaxies and massive black holes — build up quickly in the history of the universe,” he said. “Amazingly, this is contrary to hierarchical structure formation. The paradox is resolved once one realizes that dark matter grows hierarchically, but ordinary matter doesn’t. The normal matter that makes up visible galaxies and super-massive black holes collapses more efficiently, and this was true also when the universe was very young, giving rise to anti-hierarchical formation of galaxies and black holes.”

So, that means that big galaxies and super-massive black holes come together quickly, and smaller bits like our own Milky Way galaxy — and the comparatively small black hole at its center — form more slowly. The galaxies that formed those first super-massive black holes are still around, Kazantzidis said.
The new simulations done on supercomputers were able to resolve features that were 100 times smaller, and revealed details in the heart of the merged galaxies on a scale of less than a light year.

Because of this, the astronomers were able to see two things: First, gas and dust in the center of the galaxies condensed to form a tight nuclear disk. Then the disk became unstable, and the gas and dust contracted again, to form an even denser cloud that eventually spawned a super-massive black hole.

The implications for cosmology are far-reaching, Kazantzidis said.

“For example, the standard idea — that a galaxy’s properties and the mass of its central black hole are related because the two grow in parallel — will have to be revised. In our model, the black hole grows much faster than the galaxy. So it could be that the black hole is not regulated at all by the growth of the galaxy. It could be that the galaxy is regulated by the growth of the black hole.”

In the image, the panel illustrates the complexity of dynamical evolution in a typical collision between two equal-mass disk galaxies. The simulation follows dark matter, stars, gas, and supermassive black holes, but only the gas component is visualized. Brighter colors indicate regions of higher gas density and the time corresponding to each snapshot is given by the labels. The first 10 panel images measure 100 kpc on a side, roughly five times the diameter of the visible part of the Milky Way galaxy. The next five panels represent successive zooms on the central region. The final frame shows the inner 300 pc of the nuclear region at the end of the simulation. Credit: Ohio State University

This new model could also help astronomers who are searching the skies for direct evidence of Einstein’s theory of general relativity: gravitational waves.

According to general relativity, any ancient galaxy mergers would have created massive gravitational waves — ripples in the space-time continuum — the remnants of which should still be visible today.

New gravitational wave detectors, such as NASA’s Laser Interferometer Space Antenna, were designed to detect these waves directly, and open a new window into astrophysical and physical phenomena that cannot be studied in other ways.

Scientists will need to know how super-massive black holes formed in the early universe and how they are distributed in space today in order interpret the results of those experiments. The new computer simulations should provide a clue.

See this link for videos of the models of galaxy collisions.

Source: Ohio State University

14 Replies to “Colliding Galaxies Created the First Black Holes”

  1. These very early galaxies would have only produced measurable gravity waves if the two black holes directly collide. The gravitational radiation would have a wavelength on the order of the radii of the two black holes, which maybe some shorter wavelength harmonics. The shorter wavelength harmonic stuff might be able to detect with the LIGO. The gravity wave Fabrey-Perot-Michelson interferometers have kilometer length, and so gravitational waves much longer than this would not be detected. We must also keep in mind that gravity waves are redshifted just as optical radiation, and these waves would be stretched out by a z ~ 8 factor. The LISA detector is much more likely able to detect these gravitational waves.

    Of course there are very weak gravity waves formed by the dynamics of the two galaxies at large, but we will not be able to detect these. The wavelengths would be comparable to the scale of our own galaxy. You need at least a quarter wave stack or quadrupole to detect anything.


  2. Your headline is really misleading. While I’m willing to accept this as a plausible model for the formation of the first *supermassive* black holes, I don’t accept it as a model for the creation of the first black holes in general. Those almost certainly were the result of core collapse events in the remnants of population III stars.

  3. The first black holes must have come from the earliest PopIII stars. Prior to then there was nothing capable of producing black holes. Further the very earliest phase of the universe has an entropy density much lower than what is required for black holes. This involves the question on how the universe had such low entropy. The first part of this essay does mention formation of the first supermassive black holes.

    The question on how black holes came about in sufficient number and mass is unsolved. PopIII star models don’t appear to cooperate very well. So we are faced with a sort of goldilocks problem. The universe does fortunately appear to be such there are not to many black holes. Some early cosmology models had the big bang producing almost entirely nothing but black holes. But now we face the other problem of how they formed in the first place and settled into galaxy cores.


  4. We know this information because a computer program told us it was so. While we learn much of our universe from computer models, we should not forget that their output depends on the modeler’s input. If the initial parameters are wrong, then the results will be wrong. The term for that is GIGO, or “Garbage in, Garbage Out”.

  5. black holes and visible matter fulfill the ultimate question of whether the chicken or the egg came first. Black holes attract dust and gas, of which gravitational collapse is necessary to form more black holes. Without black holes there would not even be matter and anti-matter particle pair creation, of which our entire visible universe has an apparent excess of normal matter. Everybody wants to say that colliding galaxies, huge clouds that compress gases, and supernovas form black holes, but there is not enough significance given for the fact that matter exists because of black holes. The issue needs to be synthesized with the big-bang theory, because a black hole will consume and form equal amounts of matter and anti-matter. Seems likely to me that “big-bang” explosions have been happening throughout eternity, and that the excess of normal matter in our universe is proximity related to the nearest most recent CMB evidence that we see.

  6. First, gas and dust in the center of the galaxies condensed to form a tight nuclear disk. Then the disk became unstable, and the gas and dust contracted again, to form an even denser cloud that eventually spawned a super-massive black hole.

    I think this would spawn a lot of star formation, but not directly a black hole as the text suggests. It may be that the text just left out a part that could be “then came the big stars, which lived hot and died fast and left over black holes that eventually formed the first black holes, which could collide to make the SMBH”.
    It doesn’t make a lot of sense that a large cloud of gas should collapse directly into a black hole. If such things were possible in the early universe we wouldn’t have any stars today.
    Something is missing here, as well in the text as in our understanding.
    And for that I have another question: We found the first SMBH have built in less than 1 Gyr. If they have grown by galaxy collisions, and, therefore, by mergers of smaller BH, I wonder if this is at all possible? How long does it take for two BH to merge? There is a lot of angular momentum that must be taken away. However, I don’t know the efficiency of gravitational waves, but I don’t expect this effect to be very efficient. Otherwise we should see much more mergers, I guess, and possibly stronger (and detectable) gravitational waves.

  7. It is a consistency simulation I take it, the actual SMBH mechanism is still to be found.

    The take home messages would then be: a) yes it’s possible and b) DM isn’t BM (yet again).

    @ DrFlimmer:

    If they have grown by galaxy collisions, and, therefore, by mergers of smaller BH, I wonder if this is at all possible?

    Collective effects? The protoplanetary disk have similar problems, and there are a lot of interesting mechanisms helping out. (Magnetism and “gravitational viscosity” of slingshots, IIRC.)

    @ Maddad:

    their output depends on the modeler’s input.

    The same could be said for theories. That is not a problem.

    These are physical simulations, not databases, so constrained already there – the outputs depend _in a specific way_ on the modelers input. And science in general proceed by testing, see the thread on how the models come from the opposite corner.

    A GIGO theory of science methods can’t explain any of that, it is itself GIGO.

  8. @ Torbjorn Larsson OM

    Yeah, sure. But the problem is that BH do not have the ability to lose angular momentum by magnetism; they cannot produce jets like accretion disks. Slingshots may be possible, but how many slingshots do you need to settle them? Where are those “shooting BH’s” (ok, maybe invisible, but still ;))?

  9. I suspect that fairly large BHs emerged during the reionization period. It is not clear how this happened exactly. The initial implosions of hydrogen generated popIII stars, and maybe some of these went into a runaway process of implosion into a BH at the core. As far as I know models of this are not entirely friendly towards this. Yet there are these intermediate mass BH’s of 100-1000 solar masses that have been found, which might have been precursors for SMBHs.

    The problem we have of course is that with the collision of two galaxies the coalescence of their central BHs might not be assured. Largely the BHs will scatter off of each other. Largely they will gravitationally interact as two scattering bodies in a Newtonian sense. GR effect do not dominate until they two BH’s approach each other very closely. So even with the collision of two galaxies the direct collision of their BHs is a bit like firing two guns at each other from a kilometer distance and expecting the bullets to collide. There must be some sort of attenuating process that reduces the energy of the two black holes. So two black holes in this process can enter into a mutual orbit, and where the reduction in orbital energy results in the two BH’s in-spiralling towards each other. Even though black holes are gravitational pits of such enormous gravity they pull material to a region outside the universe, it is not easy to get lots of material into them or to get them to collide with each other.

    Black holes do not have magnetic fields. Magnetic fields and MHD physics associated with BHs is due to the behavior of material in accretion disks around BHs.


  10. At first the theory looks plausible but pretty soon you discover flaws.

    Because of this, the astronomers were able to see two things: First, gas and dust in the center of the galaxies condensed to form a tight nuclear disk.

    How can a tight nuclear disk being formed in the centre of the galaxy if all the mass of the galaxy is trying to rip it apart out of the galaxy centre?

    Also the existence of galaxy means also lot of stars that will collapse into black holes all over the place. The centre contains more stars so the chance of a becoming a black hole in this neighbourhood is bigger and also the collision of black holes and black holes with normal stars are higher increasing the chance that more black holes are formed in the centre than outside.

    One big gas disk forming a massive black once is probably impossible, but one big black hole formed out of the stars around that, and eventually sink to the centre is far more plausible.
    Actually the black hole does not sink to the centre, the galaxy stars will change orbit to start rotating more and more around the biggest mass over the billions of years in my opinion.

  11. Super Relativity has made drastic changes to the original Ether that Newton, Maxwell, Lorentz, Einstein wrote about. Only Lorentz believed the ether is motionless. SR states that constants including light will vary by energy density and tension. That scientific advances and inventions are made using incorrect scientific beliefs of physical phenomena, because of this mysterious ether. Perhaps the ether is instantaneous supergravity or the zero point energy vacuum? The Eridanus void is believed to be a 1 billion LY diameter black hole that is 6 to 10 billion LY away. If it emits x-ray jets, how can they be detected? Would this huge black hole and all black holes contain the ether of nothingness until they vanish?

  12. Einstein was right about the shortcomings of Quantum Mechanics and so therefore String Theory is also the incorrect approach. As an alternative to Quantum Theory there is a new theory that describes and explains the mysteries of physical reality. While not disrespecting the value of Quantum Mechanics as a tool to explain the role of quanta in our universe. This theory states that there is also a classical explanation for the paradoxes such as EPR and the Wave-Particle Duality. The Theory is called the Theory of Super Relativity. This theory is a philosophical attempt to reconnect the physical universe to realism and deterministic concepts. It explains the mysterious.

  13. I have the odd impression that the last two entries here violate the comment policy…..

  14. Yes Maddad, exactly right. Unknown quantities, forces, effects, ect.. can never be accounted for in computer models becausethey are, well, unknown.

    A scientist creating a model to explain how a TV works would never be successful if he had no knowledge of electricity.

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