Can Black Holes Explain Dark Matter? New Study Helps Disprove the Idea

By Chelsea Gohd | October 11, 2018 9:51 am
black hole

A new study casts doubt on the long lingering idea that black holes might explain dark matter. (Credit: NASA’s Goddard Space Flight Center)

The hunt for a dark matter explanation seems endless, but now we can mostly rule out one often mentioned potential culprit: black holes.

“The idea of primordial black holes as dark matter is quite old, with some papers already in the ’70s when Stephen Hawking and others proposed it,” said lead study author Miguel Zumalacárregui of the Berkeley Center for Cosmological Physics. Scientists couldn’t find any proof for the idea in the ’90s, and it started to fade away as an explanation. But the 2015 detection of gravitational waves re-ignited consideration for black holes as an explanation for dark matter.

Now, after analyzing 740 of the brightest supernovas, or exploding massive stars, discovered since 2014, scientists have found none that appear to be magnified or brightened by black hole “gravitational lenses.” Gravitational lenses are an effect where black holes magnify bright objects behind them.

“Our statistical analysis showed that the majority of the dark matter (at least 60 percent) is not made of black holes,” Zumalacárregui said.

One of the common explanations for dark matter are a group of cosmic objects called MACHOs, or massive astrophysical compact halo objects. Rather than attempting to explain dark matter with widespread tiny objects, like some unknown particles, MACHOs would be large objects like black holes, dead stars and rogue planets – all large objects that are hard to see.

Gravitational Lensing

This research team based their analysis off of the understanding that unseen primordial black holes — hypothetical black holes created soon after the big bang — or any other MACHOs, would gravitationally bend light from distant objects.

So, in searching for any gravitational lensing from these bright, distant objects, the team was looking to detect lensing from black holes.

The research team found that none of these supernovas appeared to be magnified or brightened by “hidden” black hole gravitational lenses. They concluded that primordial black holes could make up no more than 40 percent of dark matter, and none of the universe’s dark matter could be made up of heavy black holes or similar objects. A currently unpublished reanalysis by the same team using data from 1,048 sypernovas brings that percentage down even further, to 23 percent, according to a statement.

“We computed that,” Zumalacárregui said, “if black holes were all of the dark matter, we would have seen about 8 significantly magnified supernovae. In addition, if all of the dark matter was in the form of black holes, then most of the space would be empty and this makes the vast majority of the supernovas (excluding the magnified ones) be slightly dimmer than they would if dark matter was evenly distributed.”

Light Dark Matter

According to this work, we can’t entirely exclude black holes from dark matter yet, but it shows that there must be much more to the explanation.

“Our work reinforces models of light dark matter (including elementary particles) and tells us that they have to be distributed relatively smoothly, not forming heavy compact objects,” Zumalacárregui said. “It’s not as exciting as if we had found evidence for black holes (as dark matter), but it’s a step in the right direction.”

This work was published Oct. 1, 2018 in the journal Physical Review Letters.

CATEGORIZED UNDER: Space & Physics, top posts
MORE ABOUT: cosmology
  • mpc755

    Dark matter is a supersolid that fills ’empty’ space, strongly interacts with ordinary matter and is displaced by ordinary matter. What is referred to geometrically as curved spacetime physically exists in nature as the state of displacement of the supersolid dark matter. The state of displacement of the supersolid dark matter is gravity.

    The supersolid dark matter displaced by a galaxy pushes back, causing the stars in the outer arms of the galaxy to orbit the galactic center at the rate in which they do.

    Displaced supersolid dark matter is curved spacetime.

    • Uncle Al

      Aside from violating all observation, diverging from all empirically validated theory, and being untestable…the foregoing a goat rodeo eating word salad,


      • OWilson

        Empirical observation in science is boring, I know, but it’s really all we have to test the unlimited cosmology theories, out there!

        Even Einstein’s thought experiments required observational evidence to become validated!

        • Uncle Al

          I vote Right Wing: Galileo and Popper, not Aristotle and Bayes.

          • OWilson

            Theory, absent empirical evidence, defines religion! :)

          • 7eggert

            I declare gnostic atheism to be a religion too, as soon as it’s missionaries try to convert everybody.

          • OWilson

            And what would you call just “an open mind on the subject”? :)

          • 7eggert

            Agnostic theist or agnostic atheist. “I believe in God but might be wrong”, “I believe there is no god, but I may be wrong”.

    • 7eggert

      As I said before, barionically equal galaxies would need to displace that supersolid differently. You’d need a dark matter displacing that dark supersolid matter.

      • mpc755

        Thet dobdisplace the supersoild dark matter differently depending on how compact or diffuse they are.

        • 7eggert

          I was talking about galaxies of equal (baryonic) mass and density having different gravity lensing aka. different amounts and distribution of dark matter.

          I’d prefer your model or something similar or DM being a mathematical oddity.

          • mpc755

            Provide an example of two ‘identical’ galaxies that appear to have different amounts of dark matter. I’m suggesting that is not possible.

            If galaxies appear to have different amounts of dark matter, due to gravitational lensing, then there will be something different about the galaxies. Either the baryonic matter will be distributed differently or the baryonic matter will be moving at different speeds between the two galaxies.

          • 7eggert

            I’m not allowed to link to the presentation and I’m not going to watch the two hours just for you.

          • mpc755

            Okay. So you have no evidence of two ‘identical’ galaxies with different amounts of dark matter.

            You could always just post the galaxies designations (ie. names)

          • 7eggert

            After I read them from that 2 hours of presentation video.

          • mpc755

            Post the title of the video.

          • 7eggert

            “No dark matter” on youtube, length 1:45:25. Unfortunately even YT links aren’t allowed here.

          • mpc755

            They think the galaxy has no dark matter because it is too diffuse to displace the dark matter into a halo.

          • 7eggert

            While a few minutes later, they name a diffuse galaxy with dark matter, 99 % of the matter at the center is dark. Sorry, the names were in the posting that didn’t make it, and I’m in a hurry now.

          • mpc755

            The galaxies are different.

            ‘Astronomers Discover New Galaxy That Is 99.99% Dark Matter’

            > “A relatively large fraction of the stars is in the form of very compact clusters, and that is probably an important clue.”

            The more compact the cluster the greater the displacement of the supersolid dark matter connected to and neighboring the cluster, the greater the displaced dark matter pushes back and exerts pressure toward the cluster, the faster the stars in the cluster move.

            The other diffuse galaxy does not consist of very compact star clusters.

      • Uncle Al

        Imagine a curve fit absent both a function and its application..

        • 7eggert

          That would be e^x?

        • OWilson

          “And though the holes were rather small
          They had to count them all
          Now they know how many holes it takes to fill the Albert Hall”

          Sgt. Pepper

  • Kurt Stocklmeir

    I know a lot of small galaxies have dark stars but I can not prove it – God did this – the dark stars are not black holes – this is not true for big galaxies Kurt Stocklmeir

    • 7eggert

      What are dark stars? Brown dwarfs? White dwarfs? Neutron stars? The yet hypothetical quark-gluon-stars?

      Also why would our galaxy not have dark stars?

      • Mike Richardson

        Actually, once white dwarves have cooled down, they would be compact dark stars (the corpses of former main sequence stars, and smaller than Earth, but still stellar objects in terms of their origins). Given enough time, neutron stars would also cool down and become dark.

      • Kurt Stocklmeir

        7eggert when I say dark stars I am talking about stars like brown dwarfs – our galaxy has a lot of brown dwarfs but they are not dark matter – use bing search brown dwarf dark matter – a lot of small galaxies orbit our galaxy – some small galaxies have normal gravity – dumb theories that say when there is not a lot of gravity force of gravity increases are wrong – some small galaxies look like they have extra gravity – when God made some galaxies God used a lot of dark stars – small galaxies can look like they have extra gravity because of tidal forces of big galaxies – there is a lot of gas between galaxies and the gas can change orbit of stars associated with small galaxies where it looks like there is dark matter – star clusters do not have dark matter – use bing search star cluster dark matter Kurt Stocklmeir


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