Astronomers have been finding some extremely old supermassive black holes, ones that formed when the Universe was quite young. But they were puzzled at how a black hole could grow to such tremendous size when the Universe itself was just a toddler.
Astronomers have now found a unique set of conditions were present half a billion years after the Big Bang that allowed these monster black holes to form. An unusual source of intense radiation created what are called “direct-collapse black holes.”
“It’s a cosmic miracle,” said Volker Bromm of The University of Texas at Austin, who worked with several astronomers on the finding. “It’s the only time in the history of the universe when conditions are just right for them to form.”
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The conventional understanding of how black holes form is called the accretion theory, where an extremely massive star collapses and black hole “seeds” are built from the collapse by pulling in gas from their surroundings and by mergers of smaller black holes. But that process takes a long time, much longer than the time these quickly forming black holes were around. Plus, the early universe didn’t have the quantities of gas and dust needed for supermassive black holes to grow to their gigantic size.
The new findings suggest instead that some of the first black holes formed directly when a cloud of gas collapsed, bypassing any other intermediate phases, such as the formation and subsequent destruction of a massive star.
Of course, like any black hole, these “direct collapse” black holes can’t be seen. But there was strong evidence for their existence, as they are needed to power the highly luminous quasars detected in the young universe. A quasar’s great brightness comes from matter spiraling into a supermassive black hole, heating to millions of degrees, creating jets that shine like beacons across the Universe. But since the accretion theory doesn’t explain supermassive black holes in extremely distant — and therefore young — universe, astronomers couldn’t explain the quasars either. This has been called “the quasar seed problem.”
“The quasars observed in the early universe resemble giant babies in a delivery room full of normal infants,” said Avi Loeb from the Harvard-Smithsonian Center for Astrophysics, who worked with Bromm. “One is left wondering: what is special about the environment that nurtured these giant babies? Typically the cold gas reservoir in nearby galaxies like the Milky Way is consumed mostly by star formation.”
But In 2003, Bromm and Loeb came up with a theoretical idea to get an early galaxy to form a supermassive seed black hole, by suppressing the otherwise prohibitive energy input from star formation. They called the process “direct collapse.”
“Begin with a “primordial cloud of hydrogen and helium, suffused in a sea of ultraviolet radiation,” Bromm said. “You crunch this cloud in the gravitational field of a dark-matter halo. Normally, the cloud would be able to cool, and fragment to form stars. However, the ultraviolet photons keep the gas hot, thus suppressing any star formation. These are the desired, near-miraculous conditions: collapse without fragmentation! As the gas gets more and more compact, eventually you have the conditions for a massive black hole.”
This set of cosmic conditions appears to have only existed in the very early universe, and this process does not happen in galaxies today.
To test their theory, Bromm, Loeb and their colleague Aaron Smith started studying a galaxy called CR7, identified by a Hubble Space Telescope survey called COSMOS as being around at less than 1 billion years after the Big Bang.
David Sobral of the University of Lisbon had made follow-up observations of CR7 with some of the world’s largest ground-based telescopes, including Keck and the VLT. These uncovered some extremely unusual features in the light signature coming from CR7. Specifically, the Lyman-alpha hydrogen line was several times brighter than expected. Remarkably, the spectrum also showed an unusually bright helium line.
“Whatever is driving this source is very hot — hot enough to ionize helium,” Smith said, about 100,000 degrees Celsius.
These and other unusual features in the spectrum meant that it could either be a cluster of primordial stars or a supermassive black hole likely formed by direct collapse.
Smith ran simulations for both scenarios and while the star cluster scenario “spectacularly failed,” Smith said, the direct collapse black hole model performed well.
Also, earlier this year, researchers using combined data from the Chandra X-ray Observatory, Hubble Space Telescope, and Spitzer Space Telescope to identify these possible black hole seeds. They found two objects, both of these matched the theoretical profile in the infrared data. (read their paper here.)
It seems astronomers are “converging on this model,” Smith said, for solving the quasar seed problem and the early black hole conundrum.
Bromm, Loeb and Smith’s work is published in the journal Monthly Notices of the Royal Astronomical Society.
RAS, Harvard-Smithsonian CfA, Press release for NASA’s detection of direct collapse black holes earlier this year.
9 Replies to “A ‘Cosmic Miracle’: Indications Of Early Forming ‘Direct Collapse’ Black Hole Seen”
To me, a direct collapse SMBH’s was an inevitable event after the hyper expansion of the Universe.
When the Big Bang occurred, pressure and energy was equal through out the new Universe. It was so tremendous and homogeneous that any SMBH could not form. They would not form until the pressure lessened or diminished. When the Universe grew to a size where the pressure reduced enough to no longer force the hyper expansion, the very first direct collapse SMBH had to occur. And the size of these were driven by the energy they absorbed.
This was also the very first time that dark energy started to cause expansion of the Universe. But because of the small size of the Universe, there was very little dark energy expansion. So, the Universe slowed down it’s expansion for a very long time. It only recently obtained the volume so that DE could actually begin to accelerate the expansion.
Oh, and there should be either a complete total void at the center of the Universe or there should be the Grand Daddy of all SMBH. Why? The expansion should have had a blow out when the hyper expansion stopped. The center of the Universe would eventually not have stable pressure and heat all around. Expansion at the center would have either pushed all the mass and energy outwards, or as soon as the unbalanced pressures came back to the center, it should have collapse into the Grand Daddy of all SMBH.
Where’s the Math? Yeah, it’s still being collected but may never be published.
isn’t it also possible that the universe might not be the age we estimate it to be?
yes. it could be older, “could” being the key word here as evidence and observation points to the current estimate.
The Universe could be much older if it had multiple “starting” points. Just like future astronomers might not ever know the Universe consists of more than our own galaxy do to DE expansion, We might not ever see parts of the Universe beyond the CMB to prove the absolute size of the Universe. Therefore, it’s absolute age might never be known.
I have never understood the logic of this idea. If the universe were expanding rapidly in all directions why would matter suddenly clump together enough to form a super massive black hole. I went to conference in Philly a few years ago and a couple of the name physicists were there taking questions from the public. I managed to ask them one question and the three were totally stumped and just moved on. My question was roughly: We do not really know what the pre-Big Bang singularity was and nor do we know what the super massive black hole singularity is. We can’t explain super massive black hole formation. Why is it no one at least publicly has considered the possibility that these super massive black holes are actually fragments of the original singularity?
To be honest I totally blind sided them but I think too many scientists are pushing complex, low odds solutions based on existing theory rather than observation. All explosions leave finger prints and fragments including the hyper-novas. Logically, it is not out of line to suggest the Big Bang also left fragments of the singularity. And by extension logical for galaxies forming around the fragments. It fits with what we can see. Einstein said that his experience in the Swiss patent office was crucial to his later theories and their success since he learned how things worked in reality. Science today is about computer models and it is easy to simply make observations fit the model. Just a thought.
First, we have several ideas what formed the Universe. But none of the ideas are provable. That’s why you’ll see very few people explain what it was the caused the Universe. Because the math allows a near infinite amount of energy to be stored in a sub-plank length object, it’s probably a pretty good bet that is what formed the Universe. And because these objects could be made out of pure energy, it’s easy to see why we could end up with a multiverse of near infinite amount of Universes.
See my comment on SMBH’s. It’s impossible for any BH to form if all the pressure everywhere is so high as to be able to form a BH everywhere. Where would the center be? You would have equal collapsing everywhere. And as long as pressure remained constant everywhere at an absolute fixed number above what is necessary to cause a BH, no BH would be formed. As soon as a part of the Universe’s pressure reduced below the threshold there exists a brief instant where SMBH collapse can occur. It happened once in the lifetime of our Universe and will never happen again.
The Big Bang wasn’t an explosion.
It was something that expanded from a very very small point in all directions with super heat and pressure. The vectors of which did not line up. For the lack of a better explanation, the vectors were bouncing off the edge of the Universe and each other. This caused an homogeneous early Universe. Something an explosion could not do no matter how big or contained it was. And the Universe was not contained.
What if we eventually find that black holes are the source of gravity? That would mean that they appear on the quantum scale and quite possibly hold all matter together? This leads to the idea that black holes came before galaxies. That might solve the dark matter problem quite well actually and explain spooky actions at a distance, even remove dark matter from unified theory? Reboot…?
Thanks for the mind bending Nancy!
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