I need to know when did the first black holes appear?
Possibly before the first stars, but this is uncertain. They are difficult to detect save by gravitational effects on nearby objects, which obviously must be very luminous.
Can you elaborate further?
My understanding of the early Universe puts stars as the first massive objects able to form due to gravitational attraction of hydrogen gas (once the Universe had cooled sufficiently to allow recombination.) My understanding is quite limited as a novice but I have recently finished The First Three Minutes so have a basic laymans knowledge.
How can BH's form prior to massive objects? What mechanism is proposed for this? My current understanding only places massive stars as being sufficiently massive and sufficiently dense to allow for a core collapse resulting in BH formation?
Are you reffering to very small BH's with very short lifespans?
Your insight is greatly appreciated.
"One key aspect to the early Universe is that the gas available to make stars did not have metals (which, to astronomers, mean every element except hydrogen and helium), since metals came later as a result of nuclear fusion in the stars themselves. This effectively made cooling of gas slow and is thought to have lead to a comparitively larger proportion of massive stars; some of which exceded several hundred times the mass of the sun. By comparison, we are only aware of stars reaching ~150 times the mass of the sun in the nearby Universe. The question about how many black holes would have formed is of significant debate and currently a topic of theoretical astronomy. It is likely, however, that in the early Universe, when the size of the Universe was small compared to today, many of these first black holes merged to give rise to increasingly more massive black holes. These massive black holes could then quickly "sink" to the centers of what would become the galaxies. This is a leading theory for how the supermassive black holes, commonly found at the centers of galaxies, formed over cosmic history." From NASA's Ask A Astrophysicist, February 16, 2011: http://imagine.gsfc.nasa.gov/docs/ask_astro/answers/110216a.html
Perhaps there is new information about black holes since February 2011.
It is also possible that black holes can form very early in the universe shortly after the big bang [primordial black holes].
Thanks yenchin Foremost, we know blackholes exist. I was just reading about the blackhole in our galaxy.
It is possible local overdensities could have existed and collapsed to form primordial black holes in the very early universe. These may have been, or seeded the formation of supermassive black holes.
The December 8, 2011 Nature article ,Two ten-billion-solar-mass black holes at the centres of giant elliptical galaxies, by Nicholas J. McConnell et al :
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