Are Black Holes and Dark Matter the Same? Astrophysicists Upend Textbook Explanations

Supermassive Black Hole Artist's Rendition

This animation shows an artist’s rendition of the cloudy structure revealed by a study of data from NASA’s Rossi X-Ray Timing Explorer satellite. Credit: Wolfgang Steffen, UNAM

Upending textbook explanations, astrophysicists from the University of Miami, Yale University, and the European Space Agency suggest that primordial black holes account for all dark matter in the universe.

Proposing an alternative model for how the universe came to be, a team of astrophysicists suggests that all black holes—from those as tiny as a pinhead to those covering billions of miles—were created instantly after the Big Bang and account for all dark matter.

That’s the implication of a study by astrophysicists at the University of Miami, Yale University, and the European Space Agency that suggests that black holes have existed since the beginning of the universe ­­and that these primordial black holes could be as-of-yet unexplained dark matter. If proven true with data collected from this month’s launch of the James Webb Space Telescope, the discovery may transform scientific understanding of the origins and nature of two cosmic mysteries: dark matter and black holes.

“Our study predicts how the early universe would look if, instead of unknown particles, dark matter was made by black holes formed during the Big Bang—as Stephen Hawking suggested in the 1970s,” said Nico Cappelluti, an assistant professor of physics at the University of Miami and first author of the study slated for publication in The Astrophysical Journal.

“This would have several important implications,” continued Cappelluti, who this year expanded the research he began at Yale as the Yale Center for Astronomy and Astrophysics Prize Postdoctoral Fellow. “First, we would not need ‘new physics’ to explain dark matter. Moreover, this would help us to answer one of the most compelling questions of modern astrophysics: How could supermassive black holes in the early universe have grown so big so fast? Given the mechanisms we observe today in the modern universe, they would not have had enough time to form. This would also solve the long-standing mystery of why the mass of a galaxy is always proportional to the mass of the supermassive black hole in its center.”

Dark matter, which has never been directly observed, is thought to be most of the matter in the universe and act as the scaffolding upon which galaxies form and develop. On the other hand, black holes, which can be found at the centers of most galaxies, have been observed. A point in space where matter is so tightly compacted, they create intense gravity.

Co-authored by Priyamvada Natarajan, professor of astronomy and physics at Yale, and Günther Hasinger, director of science at the European Space Agency (ESA), the new study suggests that so-called primordial black holes of all sizes account for all black matter in the universe.

Did Black Holes Form Immediately After the Big Bang?

How did supermassive black holes form? What is dark matter? In an alternative model for how the Universe came to be, as compared to the ‘textbook’ history of the Universe, a team of astronomers propose that both of these cosmic mysteries could be explained by so-called ‘primordial black holes’. In the graphic, the focus is on comparing the timing of the appearance of the first black holes and stars, and is not meant to imply there are no black holes considered in the standard model. Credit: ESA

“Black holes of different sizes are still a mystery,” Hasinger explained. “We don’t understand how supermassive black holes could have grown so huge in the relatively short time available since the universe existed.”

Their model tweaks the theory first proposed by Hawking and fellow physicist Bernard Carr, who argued that in the first fraction of a second after the Big Bang, tiny fluctuations in the density of the universe may have created an undulating landscape with “lumpy” regions that had extra mass. These lumpy areas would collapse into black holes.

That theory did not gain scientific traction, but Cappelluti, Natarajan, and Hasinger suggest it could be valid with some slight modifications. Their model shows that the first stars and galaxies would have formed around black holes in the early universe. They also propose that primordial black holes would have had the ability to grow into supermassive black holes by feasting on gas and stars in their vicinity, or by merging with other black holes.

“Primordial black holes, if they do exist, could well be the seeds from which all the supermassive black holes form, including the one at the center of the Milky Way,” Natarajan said. “What I find personally super exciting about this idea is how it elegantly unifies the two really challenging problems that I work on—that of probing the nature of dark matter and the formation and growth of black holes—and resolves them in one fell swoop.”

Primordial black holes also may resolve another cosmological puzzle: the excess of infrared radiation, synced with X-ray radiation, that has been detected from distant, dim sources scattered around the universe. The study authors said growing primordial black holes would present “exactly” the same radiation signature.

And, best of all, the existence of primordial black holes may be proven—or disproven—in the near future, courtesy of the Webb telescope scheduled to launch from French Guiana before the end of the year and the ESA-led Laser Interferometer Space Antenna (LISA) mission planned for the 2030s.

Developed by NASA, ESA, and the Canadian Space Agency to succeed the Hubble Space Telescope, the Webb can look back more than 13 billion years. If dark matter is comprised of primordial black holes, more stars and galaxies would have formed around them in the early universe, which is precisely what the cosmic time machine will be able to see.

“If the first stars and galaxies already formed in the so-called ‘dark ages,’ Webb should be able to see evidence of them,” Hasinger said.

LISA, meanwhile, will be able to pick up gravitational wave signals from early mergers of primordial black holes.

For more on this research, see Black Holes Could Be Dark Matter – And May Have Existed Since the Beginning of the Universe.

Reference: “Exploring the high-redshift PBH-ΛCDM Universe: early black hole seeding, the first stars and cosmic radiation backgrounds” by N. Cappelluti, G. Hasinger and P. Natarajan, Accepted, The Astrophysical Journal.
arXiv:2109.08701

23 Comments on "Are Black Holes and Dark Matter the Same? Astrophysicists Upend Textbook Explanations"

  1. Schinud omsub | January 3, 2022 at 8:04 am | Reply

    The veracity of Physics never changes. It’s explanation and definition by human regularly do.

  2. How do primordial black holes explain galaxy rotation curves? They would have to somehow be clustered within galaxies rather than between them–but their interaction with normal matter within our own galaxy would surely have revealed their presence by now.

    • Yes. If 95% of the mass of the galaxy were in the form of primordial black holes and the galaxy still holds its shape, it would require that the primordial black holes spread out in a “halo” in and around the galaxy (just like the purported “dark matter” is hypothesized to be distributed).

      That density also means that every few million years a primordial black hole should collide with a planetary object within our solar system. For all appearances that should look like an asteroid impact, but depending on the momentum at impact time, either the primordial black hole should exit from the opposite side of the planet (creating an “exit wound” opposite the entry crater) or settle in to an orbit within the core of the planet creating seismic patterns (and of course, gradually grow by consuming ordinary matter, and in a few billion years, consume the whole planet). Such features should be discernible if we start looking for them.

      Come to think of it, a collision with a primordial black hole wouldn’t leave much of a wound on a planet – as the contact area of the event horizon with the planet is extremely small, the amount of kinetic energy transferred to the planet is also extremely small. A primordial black hole with the mass of Apophis would would have an event horizon with the diameter of an oxygen atom, and the amount of in-falling matter as it passes through a planet would be negligible. However it should leave a tell-tale mark due to the effects of the steep gravity well – maybe a small cylinder of distorted rock, which would stand out as an anomaly.

  3. … bring some shnaps and that story will make some sense… yeah, I bet Germans habe eine word for just that…

    • Ja, wir haben viele Worte um Dummköpfe wie dich zu beschreiben – Blödian, Hohlkopf, Esel, Hornochs, Schwachmat, Dussel, Hohlbirne, Spacken, Eiernacken, Dödel, Depp, Dummian, Tubel, Tschumpel, Lööli, Dämel, Dämlack, Wappler, Hiefler, usw.

      Dafür braucht man kein Schnapps, weil Deutch die schönste Sprache der Welt ist.

  4. BibhutibhusanPatel | January 3, 2022 at 11:21 pm | Reply

    The similarity between black hole and dark matter is that both exert gravity.
    But alone dark matter has no gravitational effect or any ìdentity.

    The difference between dark matter and black hole is that latter ìnteracts with bosons while former does not.
    Heat energy can involve with black hole or dark matter as indivìsual.

  5. Yes, black holes and dark matter are the same. Theoretical nonsense.

  6. mememememememe | January 4, 2022 at 4:16 am | Reply

    Reading and comprehension are two very distinct skill sets….see above.

  7. Howard Jeffrey Bender, Ph.D. | January 4, 2022 at 7:06 am | Reply

    Supermassive Black Holes at the centers of galaxies and Dark Matter are two completely different subjects with different explanations. First of all, the statement “This would also solve the long-standing mystery of why the mass of a galaxy is always proportional to the mass of the supermassive black hole in its center” is not a mystery if a view of String Theory is considered, as explained in my YouTube “Creating Universities – A String Theory Way” at https://www.youtube.com/watch?v=IaxfuKXdhkg&t=6s. This same view of String Theory suggests that Dark Matter is really pseudo-matter created temporarily everywhere by string/anti-string annihilations, as described in my YouTube “Dark Matter – A String Theory Way” at https://www.youtube.com/watch?v=N84yISQvGCk&t=4s. Bring popcorn.

  8. I should know nothing about this sort of stuff. I’ve read a little and seen tv shows on the Big Bang and black hole’s.
    So I have wondered if a black hole isn’t just compacted dark matter and radiation they emanate is dark energy.
    KISS, in other words, may a simple answer be true ? I mean how hard is this to figure out ? J/K
    And rather than just gas collapsing causing a spontaneous black hole, what dark matter in the primordial universe collapsed direct to a very large black hole, and maybe dragging gas along with it. And if black holes eventually evaporate, might what’s left be dark energy ? Or even visa versa ?

  9. … So!
    If you look at two things there are some things that are the same, some that are different, and some that are to a point different and to the point same…
    … but if you decide to ignore the differences one ends up with something like topology…
    … more interesting would be to know how does the dark matter and dark energy interact with the black wholes…

    • Would ranch dressing go better on that word salad? I mean, because it’s pure bovine excrement, ranch might be the best choice, right?

  10. Gayland Machala | January 4, 2022 at 12:14 pm | Reply

    I thought it had been proven that small primordial black holes would have evaporated by now because of Hawking radiation and bigger ones were ruled out because their effects on starlight would have been observed.

    • In isolation, primordial black holes would have evaporated by now due to Hawking radiation. However, if, once in a while, a stray atom falls in, that should provide enough mass to keep the little critter going.

      Evaporating PBHs should leave behind flashes of radiation that would have faded to infra-red by now, and James Webb should be able to detect those.

      That leads to another thought… What if the reason why we detect so-called “dark matter” in a halo around a galaxy is because there is enough matter density there to keep the PBHs from evaporating? What if the PBHs outside of the matter rich areas have already evaporated? That would lead to the same “map” of “dark matter” as what we observe today.

      • Howard Jeffrey Bender, Ph.D. | January 5, 2022 at 6:12 am | Reply

        Your thought that Dark Matter in a galaxy could keep primordial Black Holes intact does sound good, but there’s an annoyance in the way. We haven’t actually detected Dark Matter as halos in galaxies – we just assume it’s there to keep the galaxy shape together. But both Andromeda and the Milky Way have their dwarf galaxies squirting in a line from the center. A Dark Matter halo would create such dwarfs everywhere. See my YouTube, “Dwarf Galaxies – A String Theory Way” at https://www.youtube.com/watch?v=HZaTxgY8NQI&t=3s for a different explanation.

        • Where in my post did I say that dark matter keeps primordial black holes from evaporating? I said that normal matter falling in might keep them intact. That would mean that intact PBH would be detected in areas with relatively high normal matter density (eg. galaxies), and that distribution coincides with the hypothetical “dark matter” distribution.

          On the other hand, string/anti-string annihilation hypothesis, although interesting, fails to explain why those gravitational effects tend to be “clumpy” (ie. confined to certain areas, like galactic haloes).

          • Howard Jeffrey Bender, Ph.D. | January 6, 2022 at 6:08 am |

            Yes, I read more into your thought about the maintenance of primordial Black Holes than you actually said. Sorry about that! However, wouldn’t primordial Black Holes be even more efficient at keeping Dark Matter in place?

            My view of string/anti-string annihilations is that they’re not clumpy, that they exist everywhere all the time. We only see their effects when normal matter is around, ie, in galaxies, and we call what we see “Dark Matter” rather than considering string/anti-string annihilations as the cause.

          • @Dr Bender: If the hypothetical string-antistring annihilations were happening homogeneously throughout the universe, then the gravitational effect of the hypothetical pseudomatter also needs to be uniform throughout the universe.

            That means, even in areas where matter is clumpy, the pseudo-matter can’t add an incremental change in comparison to baseline space-time. This means, any gravitational effects of pseudo-matter has absolutely no effect in holding a spiral galaxy together, as it simply “elevates the baseline”.

            In fact, if a uniformly distributed gravitational effect of pseudo-matter were present, the galaxies would tend to fly apart even faster, because of the “drag” imposed on the periphery by that gravitational field, am I wrong here?

          • Howard Jeffrey Bender, Ph.D. | January 7, 2022 at 6:10 am |

            Your thoughts are correct, but there may be other factors involved. You recall Einstein showed that space is curved around massive objects and that curvature defines gravity. A curved spacetime would also be more dense and should have more strings and more annihilations than the spacetime outside of, say, galaxies.

  11. Why do they keep on asking “How could supermassive black holes in the early universe have grown so big so fast?” without ever considering how very dense the early universe was?

    They don’t factor in the increased density of matter if they only view the distribution of matter as it is today. And the comment “Given the mechanisms we observe today in the modern universe, they would not have had enough time to form.” suggests that they do not include density in their calculations. Without allowing for the density, their results will always be so far off from observations as to be virtually meaningless.

    Any primordial black holes would have been literally engulfed in an all you can eat buffet. Perhaps feeding frenzy would even be an apt description since they would have been gobbling matter at rates far beyond what we see today.

    The black holes involved in this feeding frenzy may even account for the quasars at the edge of the universe. The ones that are so intense that they outshine entire galaxies. The polar jets we’ve detected from some black holes might be incredibly intense but they are as nothing when compared to those early black holes.

    Dark matter doesn’t even have to enter the picture at all.

    • Howard Jeffrey Bender, Ph.D. | January 6, 2022 at 8:38 am | Reply

      Some physicists say all the matter and energy in our universe was squeezed into a space smaller than a proton. How could that happen?

      A view of String Theory says it couldn’t, and may have answers to many of your points. Try my YouTubes, “Creating Universes – A String Theory Way” at https://www.youtube.com/watch?v=IaxfuKXdhkg&t=6s and “Active Galaxies – A String Theory Way” at https://www.youtube.com/watch?v=cCb7RYwmnS8

    • In the inflationary epoch of the big bang (the first 10^-32 seconds), although all matter existed in a volume smaller than a proton, the universe did not re-collapse in to a black hole, because space-time was expanding at a rate faster than matter could coalesce (during that period, space-time increased volume by 10^78 times).

      When the inflation ended, the density of matter was far higher than today, but much less than that needed for large clumps of matter to spontaneously collapse in to supermassive black holes. They were dense enough to collapse in to early stars, which formed stellar mass black holes millions of years later. However, there is evidence to say that supermassive black holes already existed at this time. That means, there must have been some sort of “seed” that precipitated their formation. So what astrophysicists are pondering is not “how could they grow so fast”, but “how could they form so fast?” Once formed, as you rightly pointed out, they had an all you can eat buffet.

      However, towards the middle of the inflationary phase, there could have been local clumps dense enough to collapse, but those would have been about the mass of an asteroid, forming “nano” black holes. One hypothesis postulates that such primordial black holes could have quickly merged, growing in size to attract nearby matter, and thus precipitated the formation of supermassive black holes.

  12. Frosted Flake | January 7, 2022 at 5:08 pm | Reply

    The proof is in the pudding. Eighty proof, if you want to be particular.

    Seriously? I have my money on Neutrinos being the dark matter. Along with the mass of all that light. Looking forward to first light on Webb. Then we will see something!

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