Scientists find further evidence for a population of dark matter deficient dwarf galaxies

Chinese Academy of Sciences Headquarters


This figure illustrates structure in the simulated universe, in a box 200 million light-years on each side. It is color coded, using black, green, yellow, pink and white to represent… view more

Credit: NAOC

Researchers from the National Astronomical Observatories of the Chinese Academy of Science (NAOC), Peking University and Tsinghua University have found a special population of dwarf galaxies that could mainly consist baryons within radii of up to tens of thousands of light-years. This contrasts with the normal expectation that such regions should instead be dominated by dark matter.

This study may challenge the formation theory of dwarf galaxies in the framework of standard cosmology and may provide new clues to the nature of dark matter. The results were published in Nature Astronomy on Nov. 26, 2019.

In standard cosmology, the Universe is dominated by cold dark matter and dark energy, while baryons only occupy 4.6% by mass. Galaxies form and evolve in systems dominated by dark matter (Fig. 1). In high-mass systems, the baryonic fraction may reach the universal value, i.e., 4.6%. In low-mass systems, the baryonic fraction may be much lower due to their shallow gravitational potential.

The satellite dwarf galaxies in our Local Group are found to be dominated by dark matter down to radii of a few thousand light-years. However, statistical studies of the dynamics of dwarf galaxies beyond the Local Group previously had been hampered by the extreme faintness of such systems.

Multi-wavelength data have recently made such studies possible, however.

By taking advantage of the release of 40% of the data from the Arecibo Legacy Fast (ALFA) catalogue and the Seventh Data Release of the Sloan Digital Sky Survey, a research group led by Prof. GUO Qi from NAOC has found 19 dwarf galaxies that are dominated by baryons at radii far beyond their half-optical radii ( typically a few thousand light-years). Normally, the dark matter-to-baryon mass ratio reaches 10-1000 for “typical” dwarf galaxies. Notably, most of these baryon-dominated dwarf galaxies are isolated galaxies, free from the influence of nearby bright galaxies and high-density environments.

“This result is very hard to explain using the standard galaxy formation model in the context of concordance cosmology, and thus encourages people to revisit the nature of dark matter,” said Prof. GUO.

Instead of the standard cold dark matter model, a warm dark matter model or fuzzy dark matter model might be more in line with the formation of this particular population of dwarf galaxies. Alternatively, some extreme astrophysical processes may also be responsible.

Further observations are required to understand the formation of these particular baryon-dominated dwarf galaxies.


From EurekAlert!

57 thoughts on “Scientists find further evidence for a population of dark matter deficient dwarf galaxies

      • fuzzy dark matter, no less.

        Now I’ve always been very skeptical about the existence of dark matter, but fuzzy dark matter, well that makes a lot more sense. I can buy that.

        Now what we really need to know is whether our CO2 emissions are causing unprecedented changes to the amount of fuzzy dark matter in our Local Cluster.

        I’m sure it’s worse than we previously thought.

        • Maybe we would have found it if we completed the Superconducting Super-Collider. At $10B, it would still be cheaper and more useful than all the Warmunist tech.

      • Indeed, but which data is flawed, by how much, and in what manner pretty much sums up half of the big mysteries in cosmology today. The person to navigate this crisis is guaranteed a Nobel Prize.

        Not only that, but he* will certainly prevent further head injuries from all the physicists smacking their heads against walls worldwide.

        *As English is an Indo-European language, the masculine generic is used as a default, with no insult towards some exceedingly brilliant female physicists. I have yet to find anyone insulted by receiving the name-brand over the generic in any other situation.

        • The Proto-Indo-European language from which all the existing family members descend had masculine, feminine and neuter nouns and pronouns. In the simplified grammar of Modern English, the masculine and neuter genders are combined.

          The pronoun “he” is thus masculine and neuter in gender, which of course differs from biological sex. It’s a trangender pronoun!

    • Dark matter need have no mysterious aspects. In fact, it’s a little easier to envision than is “ordinary” matter.

      It simply needs mass, but no electric charge and no magnetic dipole moment. The origin of the latter two are more difficult to imagine.

      We can’t see it because, lacking charge, it can’t emit, scatter, or absorb electromagnetic radiation.

      It’s “temperature” would simply be its mean kinetic energy.

  1. “Picture CAPTION
    This figure illustrates structure in the simulated universe, in a box 200 million light-years on each side.”

    “have found a special population of dwarf galaxies that could mainly consist baryons within radii of up to tens of thousands of light-years”

    “This study may challenge

    “”This result is very hard to explain using the standard galaxy formation model in the context of concordance cosmology”

    “Instead of the standard cold dark matter model, a warm dark matter model or fuzzy dark matter model might

    Possibly identified one unusual very small group, 19 dwarf galaxies, and the researcher(s) are ready to challenge general cosmology?

    Then there is this:

    “Further observations are required to understand the formation of these particular baryon-dominated dwarf galaxies”

    Small unusual observation, waffle words up the wazoo, models on every side and of course the “Send more money” ending.
    These researchers certainly do not fill me with wonder and interest.

    • Also :
      “By taking advantage of the release of 40% of the data from the Arecibo Legacy Fast (ALFA) catalogue and the Seventh Data Release of the Sloan Digital Sky Survey,”

      I wonder what the other 60% of the data might show.

    • The researchers who peer into their telescopes and then pronounce that the universe is largely composed of material we cannot detect are the ones who do not fill me with wonder and interest. Professor Brown from Duke called dark matter and dark energy “Fairy-Dust Models” right here on WUWT.

      How exactly do they know just how much a galaxy weighs and how fast it should be rotating? Just what should the red-shift from the Type IA Super-Novae should be now that we know that there is more than one kind of Type IA Super-Nova?

      Glad I went into engineering, not Science and particularly not Astronomy…

      • Now there, don’t be so cynical. I like the idea of warm dark matter and fuzzy dark matter, in fact I’d like some warm and fuzzy dark matter.

        Now if only we could work out how to harness warm and fuzzy dark matter and turn it into warm and fuzzy dark energy we could finally free ourselves from our dependency on DIRTY FOSSIL FUELS.

  2. There is no current problem of greater importance to cosmology than that of dark matter. Dark matter is composed of particles that do not absorb, reflect, or emit light, so they cannot be detected by observing electromagnetic radiation. Dark matter is material that cannot be seen directly. We know that dark matter exists because of the effect it has on objects that we can observe directly. link

    The conventional wisdom is that dark matter does not interact with other matter except by gravity. link

    How about an alternate explanation. We don’t understand gravity as well as we think we do.

    • There is a corollary on that one. We do not understand time as well as we think we do. Our definitions of time are based (eventually) on our definitions of distance. While I know some folks will say that time is defined in terms of the period it takes a certain wave from a certain element to oscilate a given number of times, that period is dependent on the distance between two peaks in the wave function of the electron cloud of that certain element. In other words, we can make it pretty far removed from each other, but we cannot escape the fact that distance defines time and time defines distance.

    • As electromagnetism is 10^36 times stronger than gravity and there is the clear fact that it is impossible to have any matter with mass that does not have inherent charge, maybe they are barking up the wrong tree. Protons and neurons have quarks and the electron a negative charge. We know about loc alined London dispersion forces (LDFs) between molecules. Perhaps gravity is a long-range, very weak residual force between the charges of all matter. One part in 10^36 is truly residual.

      How can they so blithely ignore this possibility. This would explain why magnetism can effectively overcome gravity.

      • Sitting on a beach the other day I was observing a marker buoy at some distance bobbing up and down on sea waves, alternatively coming in and disappearing out of my view.
        It occurred to me that what we know as gravity force could be an electromagnetic field force with wave length measured in millions or even billions of light years, therefore its intensity would depend where a particular mass (galaxy or system of galaxies) happens to be in relation to the peaks of field force propagating in both domains of space and time.

        • Don’t need any magnets, just pick up a person slightly heavier than yourself and throw him/her at a horizontal speed of at least of 8,000 m/s (5 miles per second) and two of you would meet at the other side in no time at all.

    • It appears to me that time, along with dark matter, is an idea we(collectively) made up to get a handle on causation, distance, movements, changes, astronomy, right down to the internal characteristics of sub-atomic particles.
      Time is not a “thing” such as a proton or neutron. At its base time is a sensation in the brain that occurs when we see, hear, feel, or otherwise sense changes around us. For individuals the ultimate time is when we die and cease to sense changes.
      Essentially it seems to boil down to “can we make useful things that work”. Take a pendulum. A simple pendulum works, it keeps, as best we can tell, a specific period, which is useful. Notice there are not many uses for compound pendulums, other than demonstrating chaotic, unrepeatable behavior does exist.
      Has anyone made a compound “electron” or simlar pendulum?

  3. The ancients explained the heavens with mythical analogies. Perhaps we haven’t made much progress there!

    • We just need to channel the force…err dark matter. Not sure what the difference is between them.
      Both are everywhere influencing all.

    • Read the Wiki entry on baryons for (seemingly) mythical mutterings on the nature of matter.

      I was charmed by its strangeness and lost track of whether my top and bottom were up or down.

  4. The ignored elephant in the room is that these astronomers make the tacit assumption, almost lazy, that all real matter will glow and can be assessed. There is a great chance that there might be a lot more matter out there that is cold and does not glow than there is hot, visible matter. If they take this into account, dark matter, as in dark physics and the bogeyman in the closet, is not needed to explain galactic behavior.

    A few years ago, a couple of young astrophysicists excitedly reported detecting lots of cold matter out there. They were told to shut up or get out.

    No mention of the filamentous aspects of their model, which cannot be explained by current Big Bang cosmology? Too bad. A glaring failure staring them in the face and they ignore it.

    • So, in the center of our galaxy there are 18 times as much non glowing mass as there is glowing mass?
      I do not think there is dark matter or dark energy. But the speed of things in the galaxy, the fact that our spiral galaxy still has “arms”, kind of indicates something about physics is not accounted for correctly or at all.
      I also do not believe the Universe is expanding the way they claim it is. I prefer to think that light red shifts over long distances as it loses energy.

      • “I prefer to think that light red shifts over long distances as it loses energy.”

        Well … OK … sure. Where does light lose energy to? Or is Conservation of Energy yet another confused notion?

        • Very late addendum: I thought about it for a few days then fired up a search engine. It appears that the problem of disappearing energy due to red shift is a substantial problem with ALL explanations for the red shift. Just one of the (many?) difficulties with modern cosmology apparently.

      • Based on the mass distribution of stars in our galaxy and their rotations around the presumed center of mass, either there is a lot more mass that we cannot see or the universal law of gravitation is wrong. Scientists have calculated the distribution of mass required to produce the observed orbital velocities. This distribution does not localize the mass in the center of the galaxy, for example in a more massive central black hole. This would be analogous to Kepler’s law still works, but we have the mass of the sun wrong. Kepler’s law applied to the galaxy with more central mass does not give us the velocities of the stars that we observe, based on red-shift. The mass is required to be distributed throughout the galaxy to produce star velocities that match observation. Dark matter is the fancy way of saying that theory and observation do not agree. As with the neutrino, scientists have chosen to believe the theory and claim incomplete observation. Either way, this is a fundamental discrepancy between theory and observation.

        • I wonder if the red shift is corrected for the huge gravity well the light near the center of the galaxy is coming out of to get to us. I have not looked at this data so I can not say that I know if it has or has not been so corrected. Of course, the red shift for gravity would be the same for stars moving toward us and away from us (i.e we would calculate the velocity of stars moving toward us as slower than they actually are and the velocity of those moving away as faster), but more for stars near the center than away, so should be pretty obvious to see in the data.

        • “Dark matter is the fancy way of saying that theory and observation do not agree,” and that astronomers have a problem saying “we just don’t know”

  5. When your equation doesn’t work just add a ‘ fudge’ factor. Even Einstein did it, but when he eventually found out that it was not required he just said ‘now lambda=1.
    Dark matter and dark energy are no more than fudge’ factors end eventually will be eliminated.

  6. oh ffs

    There is no such thing as dark matter. It was invented out of thin air. Has never been detected, its effects never been detected. It has apparently to date not interacted physically with the matter around it.

    and apparently now, we have galaxies that are deficient of something that never existed in the first place
    and all because some mathematical salad calculated correctly even though it made no sense (like infinite space time from dividing by 0)

    I hope in 3 cenuries from now we can look back and laugh at how much bullshit came from astronomers in the 20th and 21st centuries. the better our tech gets the dumber we get


      The Astrophysical Journal, 604:596-603, 2004 April 1
      © 2004. The American Astronomical Society.

      Weak-Lensing Mass Reconstruction of the Interacting Cluster 1E 0657-558: Direct Evidence for the Existence of Dark Matter

      Douglas Clowe
      Institut für Astrophysik und Extraterrestrische Forschung der Universität Bonn, Auf dem Hügel 71, 53121 Bonn, Germany;

      Anthony Gonzalez
      Department of Astronomy, University of Florida, 211 Bryant Space Science Center, Gainesville, FL 32611-2055

      Maxim Markevitch
      Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138

      Received 2003 October 28; accepted 2003 December 11


      We present a weak-lensing mass reconstruction of the interacting cluster 1E 0657-558, in which we detect both the main cluster and a subcluster. The subcluster is identified as a smaller cluster that has just undergone initial infall and pass-through of the primary cluster and has been previously identified in both optical surveys and X-ray studies. The X-ray gas has been separated from the galaxies by ram pressure–stripping during the pass-through. The detected mass peak is located between the X-ray peak and galaxy concentration, although the position is consistent with the galaxy centroid within the errors of the mass reconstruction. We find that the mass peak for the main cluster is in good spatial agreement with the cluster galaxies and is offset from the X-ray halo at 3.4 σ significance, and we determine that the mass-to-light ratios of the two components are consistent with those of relaxed clusters. The observed offsets of the lensing mass peaks from the peaks of the dominant visible mass component (the X-ray gas) directly demonstrate the presence, and dominance, of dark matter in this cluster. This proof of dark matter existence holds true even under the assumption of modified Newtonian dynamics (MOND); based on the observed gravitational shear–optical light ratios and the mass peak–X-ray gas offsets, the dark matter component in a MOND regime would have a total mass that is at least equal to the baryonic mass of the system.

  7. “baryons within radii of up to tens of thousands of light-years”

    Those are some really huge baryons…

  8. According to relativity both time and linear distance vary with velocity and gravitational effects from reference frame to reference frame relative to one and other. Plus every time we advance in our powers of observation we find more regular baryonic matter. Dark matter and dark energy are fudge factors that “almost” make the theoretical equations work.

  9. Mark,

    I couldn’t agree more and the same goes for dark energy.

    Dark matter makes more sense as an echo from the creation of super massive black holes. In effect, it’s an imprint on the curvature of space-time whose counter balance is the super massive black hole it surrounds, both of which were created concurrently and neither of which could exist without the other. Galaxies then arose in the gravitational potential wells between central black holes and their complementary ‘dark matter’. The evidence for this is that the amount of dark matter associated with a galaxy is strongly correlated to the size of the central black hole. I like to think of it as a standing gravitational wave associated with the creation of central black holes that was locked into place at the end of inflation.

    Dark energy seems to be the unavoidable consequence of the arrow of time. The entire EM history of the Universe is stored somewhere in the fabric of space-time. As time progresses, the fabric of space-time must expand to accommodate more history and the more Universe there is, the more places it’s expanding from and the more history must be stored. Sounds like an accelerating expansion to me, since the spatial component of space-time is expanding proportional to t^3.

    That the tech is getting better, i.e. computers are getting faster, contributes to relying more and more on unverifiable, bottom up models that lack top down constraints under the premise that a proper top down behavior will emerge, and this is the real problem.

  10. ” Dark matter is composed of particles that do not absorb, reflect, or emit light, so they cannot be detected by observing electromagnetic radiation.”
    What a great way to inoculate your theory from challenges. It sounds awfully like descriptions of why we can’t prove God exists.

    • Observations supporting the hypothesis of dark matter don’t require that the presumed substance itself radiate. The hypothesis is based upon movements of matter visible in various bands of the EM spectrum.

  11. Two previously considered competing explanations for observations of the motions of stars, galaxies and clusters are on offer, ie dark matter and modified Newtonian dynamics (MOND). Work is underway to unify these two hypotheses.

    Theoretical physicist Sabine Hossenfelder explains:

  12. I thought baryons (heavy particles) meant protons and neutrons, as opposed to leptons (light particles) such as electrons. But if baryons have radii of thousands of light years, they must be huge, much larger than the sun or even our galaxy. What if the solar system is part of one gigantic baryon?

    • They mean that baryons dominate gravity (space-time curvature) for up to thousands of light years from the center, as opposed to most galaxies where what is called dark matter dominates gravity at those distances. In other words, the gravitational influence is consistent with the mass of the stars and no dark matter is required to explain it.

      I suspect that such galaxies have no central black hole and the stars in them were ejected during a galactic collision.

  13. Dark matter is a supersolid that fills ’empty’ space and is displaced by ordinary matter.

    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 dark matter is curved spacetime. More correctly, what is referred to geometrically as curved spacetime physically exists as displaced dark matter.

    The supersolid dark matter displaced by the quarks the Earth consists of, pushing back and exerting pressure toward the Earth, is gravity.

    Displaced supersolid dark matter is gravity.

    The reason for the mistaken notion the galaxies are missing dark matter is that the galaxies are so diffuse that they don’t displace the supersolid dark matter outward and away from them to the degree that the dark matter is able to push back and cause the stars far away from the galactic center to speed up. The galaxies are too diffuse to displace the supersolid dark matter to such an extent that it causes the light to lense as it passes through the galaxies.

  14. “that could mainly consist baryons” …anyone?

    “Scientists find further evidence for a population of dark matter deficient dwarf galaxies” — anyone see an issue there?

    I understand that this platform is all about the science, but far too often the excellent papers and the highly respected (by me, for one) comments verge on the illiterate, when that should be so easy to resolve given available resources.

    Communication, duh. If it were computer code, you would be yowling.

  15. Because Elves are very flashy people and would have things like ‘Rivendell Elliptical” spelled out in bands of stars across any galaxy they inhabit.

  16. The current theory of a mass-centric (i.e., gravity forming) universe composed of visible matter and dark matter has begun to have the same type of problems as the Ptolmaic system had. Everytime there is a new discovery, another epicycle has to be added to account for its movements.

    I suspect it’s time to throw the whole scheme out, and look at completely different concepts. Now history has taught me that by the time I think of something ‘novel’, it is only novel to me; others are already working on the concept. I hope to see some interesting new concepts and theories about the universe in the near future.

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