Co-Evolution of Galaxies & Supermassive Black Holes
Posted in Active Galactic Nuclei, Astrophysics, Black Holes, Computer Aided Simulation, Cosmology, Science, Supermassive Black Holes by Michael Roberts on August 26, 2010
A recent study published in Nature suggests that ‘behemoth’ black holes billions of times more massive than our Sun found at the center of many, if not all, galaxies probably formed shortly after the Big Bang.
Supercomputer simulations conducted by Lucio Mayer, from the Institute for Theoretical Physics at the the University of Zurich, indicate that the conditions for the birth and growth of these giants could have been set in play by the merger of galaxies when the cosmos was just a few hundred million years old. The simulation found that the collision and union of two early galaxies could produce an enormous disc of rotating gas, and that this disc could become unstable and fall in on itself in rapid time.
Today, enormous black holes seem to lie at the centers of most large galaxies. Although these objects cannot be seen directly, their existence is betrayed by nearby stars whose high velocities can only be explained if they are being influenced by something with an immense gravitational attraction.
Understanding how these supermassive black holes came into being and how they evolved is a major question in astrophysics. Professor Mayer said the new study had major consequences for the apparent size relationship between supermassive black holes and their host galaxies. University of Zurich scientist, Kevin Schawinksi, added:
…it challenged the idea galaxies grew in a hierarchical fashion, in incremental steps in which gravity pulls small masses together to form progressively larger structures.”
Astrophysicists expect that in the early Universe there will be no clear relation as in the present-day Universe, since the black holes would be already very massive (because they form in only a few hundred thousand years after galaxy collisions) while the galaxies still have to grow a lot until the present time.
This, of course, would distinguish Lucio’s model from the old one in which small seed black holes are formed first from the collapse of primordial stars and then slowly grow to the present sizes. In this case, galaxies and massive black holes grow in parallel; while in our case, black holes grow much faster than galaxies.