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from the why-did-the-quasar-cross-the-event-horizon dept.
Quasars are the brightest objects in the universe, and are powered by supermassive black holes capturing matter and simultaneously accelerating particles away from them at near the speed of light. Many quasars, however, date back to the first 800 million years of the universe, long before stars were old enough to collapse, explode in a supernova, and form said supermassive black holes.
Researchers have now modeled the creation of these early black holes sans explosion.
...black holes in the very early universe could have formed by simply accumulating a gargantuan amount of gas into one gravitationally bound cloud. The researchers found that, in a few hundred million years, a sufficiently large such cloud could collapse under its own mass and create a small black hole — no supernova required.
These theoretical objects are known as direct collapse black holes (DCBHs). According to black hole expert Shantanu Basu, lead author of the new study and an astrophysicist at Western University in London, Ontario, one of the defining features of DCBHs is that they must have formed very, very quickly within a very brief time period in the early universe.
The process involves an interaction of two nearby galaxies, one over-actively forming new stars and the other highly gaseous but relatively inactive in star formation.
As new stars form in the busy galaxy, they blast out a constant stream of hot radiation that washes over the neighboring galaxy, preventing the gas there from coalescing into stars of its own. Within a few hundred million years, that starless gas cloud could accrete so much matter that it simply collapses under its own weight, forming a black hole without ever producing a star, Basu found.
According to Basu, black holes that formed at the beginning of that initial 150 Million year window would have grown rapidly, potentially increasing their mass by as much as a factor of 10,000.
Journal Referrence
Shantanu Basu and Arpan Das 2019 ApJL 879 L3 DOI:https://doi.org/10.3847/2041-8213/ab2646
(Score: 3, Interesting) by sshelton76 on Monday July 08 2019, @11:39AM
You are confused. You state that spacetime would be too flat to produce blackholes due to cosmic inflation, yet you support this theory which says the opposite.
I believe you are confusing the dark energy inflation of the current epoch, i.e. cosmic inflation with the inflationary epoch in the fractions of a second between the end of unification and the beginning of the electroweak epoch. The period from 10^-36 to 10^-32 seconds after the big bang. These are very different things. One caused the universe to be uniformly flat from the earliest periods while making the universe big enough it didn't immediately collapse in on itself, the other is just gradually pushing space apart.
You are confusing primordial blackholes (the result of spacetime disturbances seeding a collapse), with what I am talking about which are objects that started life as quantum scale black holes https://en.wikipedia.org/wiki/Virtual_black_hole [wikipedia.org]
What I'm telling you is that yes the universe is too flat for gas to collapse on it's own like that. But it's not just flatness and it's not JUST degeneracy pressure. It's the energy released from the phase transition(s) from gas to neutronium whether or not you have time for fusion along the way.
As neutronium forms, it releases neutrinos and positrons. The positrons quickly combine with electrons in the surrounding gas and release all their energy as gamma rays, this is a matter/antimatter reaction, literally the most powerful reaction possible and the energy has the effect of blasting the surrounding gas away, while the neutrinos also provide an additional outward pressure shell and pauli works to try and stabilize against further collapse.
Think about it. You can't just collapse a diffuse gas to the Chandreskar limit without it undergoing phase transitions. The laws of physics work at the speed of light and these transitions take time. Each phase transition is going to occur and when it does it's going to put out a helluva a lot of energy.
Yes at some point, gravity can overcome this, and you collapse to a black hole. But there is a limit to how much and how fast a blackhole can take in mass, this is because everything added to a blackhole increases the size of the event horizon and the expansion rate of the event horizon is limited to the speed of light. This is the surface area, not the volume. The Bekenstein bound and Bremermann's limit, work together to describe how much can be added for any given unit of time for a black hole of a given mass.
As you approach this limit, eventually you end up with a traffic jam. All of the matter in the traffic jam is gaining gravitional and probably rotational energy and effectively banging into eachother like cars on an LA freeway at rush hour. This places severe limits on blackhole growth.
To my mind the best solution to the super massive blackhole origin story is that quantum scale virtual blackholes in the spacetime foam at the big bang were scaled up during the inflationary epoch. Quantum scale blackholes don't have quite the same properties as normal blackholes. They can have literally any mass and because they pop into and out of existence so quickly they don't violate mass/energy conservation. Ergo virtual quantum scale blackholes in the atom sized pre-bigbang space foam were scaled up (along with their event horizons) during the inflationary epoch. Now they can have the event horizon of a blackhole with millions or billions of solar masses without actually having eaten anything. From here they can consume the quark gluon plasma that was left over after the transition and this would stabilize them, keeping them from evaporating due to their reduced practical mass relative to their mass as indicated by their event horizon.
If this sounds far fetched. Consider than an object 1nano meter in size would be stretched to more than 10 lightyears by this process. Ergo a blackhole the size of an electron would have an event horizon on par with the largest black holes because of the stretching that occurred in that tiny fraction of a second. They would evaporate quickly, with the event horizon shrinking back to match the mass. But the expansion and contraction rate of the event horizon is limited to the speed of light. So any plasma that formed from the universal phase transition which was behind the event horizon would be added to the mass of the blackhole keeping it from shrinking too much and from there it's an all you can eat buffet for a few hundred thousand years.
As for https://en.wikipedia.org/wiki/N6946-BH1 [wikipedia.org] the only thing we know for certain is that it is no longer visible. The currently accepted theory is that it collapsed too fast to undergo the kind of supernova and resulting neutron star that was expected for a star of that size. But it's also possible a hyper dense object such as a neutron star or black hole passed through it very quickly, and disrupted it. It's also possible it passed through the neutron phase quickly and became a quark star, maybe even turning into strange matter.
https://www.youtube.com/watch?v=p_8yK2kmxoo [youtube.com]
Regardless, this does not support the theory of collapse occurring too fast for fusion to occur, in fact it refutes it.
First off this thing was only 25 stellar masses, if it collapsed to a blackhole it would be intermediate at best, super massive holes start at 50,000 solar masses and go up to 50,000,000,000 solar masses. That's a lot of gas to eat, there would be an enormous amount of energy put off by the accretion disk and the jets. Secondly this star was a star, and it lived for hundred of millions of years.
As a star it underwent fusion for most of it's life and as a result it directly refutes the idea that you can squeeze that much mass so quickly that phase transitions cannot put out enough energy to stabilize it against further collapse, at least until the the fusion stops. Think about it, Type II supernovae are not observed in stars greater than 18 solar masses. But these clouds of gas still form stars before they collapse whether they collapse to a neutron star, a quark star a strange star a fuzzball or a black hole. But the article is trying to posit that they can just skip over the whole "being a star thing" too and while that may work in GR, it doesn't work quantum mechanically.