Alert reader Dan Baeckström recently asked about NGC 1277, as apparently some people have been making this out to be some sort of death knell for MOND.

My first reaction was NGC who? There are lots of galaxies in the New General Catalog (new in 1888, even then drawing heavily on earlier work by the Herschels). I’m well acquainted with many individual galaxies, and can recall many dozens by name, but I do not know every single thing in the NGC. So I looked it up.

NGC 1277 in the Perseus cluster. Photo credit: NASA, ESA, M. Beasley, & P. Kehusmaa

NGC 1277 is a lenticular galaxy. Early type. Lots of old stars. These types of galaxies tend to be baryon dominated in their centers. One might even describe them as having a dearth of dark matter. This is expected in MOND, as the stars are sufficiently concentrated that these objects are in the high acceleration regime near their centers. The modification only appears when the acceleration drops below a0 = 1.2 x 10-10 m/s/s; when accelerations are above this scale, everything is Newtonian – no modification, no need for dark matter.

So, is NGC 1277 special in some way? Why does this come up now?

There is a recent paper on NGC 1277 by Comerón et al. that seems to be the source of the claims of a death knell. The title is The massive relic galaxy NGC 1277 is dark matter deficient. That sounds normal for this type of galaxy, but I guess if you disliked MOND without understanding it, you might misinterpret that title to mean there was no mass discrepancy at all, hence a problem for MOND. I guess. I’m an expert on the subject; I don’t know where non-experts get their delusions.

The science paper by Comerón et al. is a nice analysis of reasonably high quality observations of the kinematics of this galaxy. Not seeing what the worry is. Here is their Fig. 19, which summarizes the enclosed mass distribution:

Three-dimensional cumulative mass profiles of NGC 1277 (Fig. 19 of Comerón et al.) Stars and the central black hole account for everything within the observed radius; dark matter (colored bands) is not yet needed.

The first thing I did was eyeball this plot and calculate the circular speed of a test particle at 10 kpc near the edge of the plot. Newton taught us that V2 = GM/R, and the enclosed mass there looks to be just shy of 2 x 1011 solar masses, so V = 290 km/s. That’s big, but also normal for a massive galaxy like this. The corresponding centripetal acceleration V2/R is about 2a0. As expected, this galaxy is in the high acceleration regime, so MOND predicts Newtonian behavior. That means the stars suffice to explain the dynamics; no need for dark matter over this range of radii.

The second thing I did was check to see what Comerón et al. said about it themselves. They specifically address the issue, saying

One might be tempted to use the fact that NGC 1277 lacks detectable dark matter to speculate about the (in)existence of Milgromian dynamics (also known as MOND; Milgrom 1983) or other alternatives to the ΛCDM paradigm. Given a centrally concentrated baryonic mass of M⋆ ≈ 1.6 × 1011 M⊙ and an acceleration constant a0 = 1.24 × 10−10 m s−2 (McGaugh 2011), a radius R = 13 kpc should be explored to be able to probe the fully Milgromian regime. This is about twice the radius that we cover and therefore our data do not permit studying the Milgromian regime 

Comerón et al. (2023)

which is what I just said. These observations do not probe the MOND regime, and do not test theory. So, in order to think this work poses a problem for MOND, you have to (i) not understand MOND and (ii) not bother to read the paper.

I wish I could say this was unusual. Unfortunately, it is only a bit sub-par for the course. A lot of people seem to hate MOND. I sympathize with that; I was really angry the first time it came up in my data. But I got over it: anger is not conducive to a rational assessment of the evidence. A lot of people seem to let their knee-jerk dislike of the idea completely override their sense of objectivity. All too often, they don’t even bother to do minimal fact checking.

As Romanowsky et al. pointed out, the dearth of dark matter near the centers of early type galaxies is something of a problem for the dark matter paradigm. As always, this depends on what dark matter actually predicts. The most obvious expectation is that galaxies form in cuspy dark matter halos with a high concentration of dark matter towards the center. The infall of baryons acts to further concentrate the central dark matter. So the nominal expectation is that there should be plenty of dark matter near the centers of galaxies rather than none at all. That’s not what we see here, so nominally NGC 1277 presents more of a challenge for the dark matter paradigm than it does for MOND. It makes no sense to call foul on one theory without bothering to check if the other fares better. But we seem to be well past sense and well into hypocrisy.

Stacy McGaugh is an astrophysicist and cosmologist who studies galaxies, dark matter, and theories of modified gravity. He is an expert on low surface brightness galaxies, a class of objects in which the stars are spread thin compared to bright galaxies like our own Milky Way. He demonstrated that these dim galaxies appear to be dark matter dominated, providing unique tests of theories of galaxy formation and modified gravity. Professor McGaugh is currently the chair of the Department of Astronomy at Case Western Reserve University in Cleveland, Ohio, and director of the Warner and Swasey Observatory. Previously he was a member of the faculty at the University of Maryland, having also held research fellowships at Rutgers, the Department of Terrestrial Magnetism of the Carnegie Institution of Washington, and the Institute of Astronomy at the University of Cambridge after earning his Ph.D. from the University of Michigan.

44 thoughts on “Is NGC 1277 a problem for MOND?”

  2. Dear Stacy, your dog is too convincing. According to all that is known and you have explained several times, dark matter should not only be dark, but also miraculous…

  3. Great stuff! Have you wondered whether, from a practical perspective, that the best way out of this mess could be to promote complementarity?

    What are the chances that an entire segment of the scientific community has settled on being ignorant and hypocritical? I submit that the chances are very low.

    When promoting complementarity,
    there doesn’t have to be an immediate answer in order to change how people view their “rivals”.

    Apart from the practical perspective however, I really find the notion so intriguing!

    For example, consider that understanding blackholes may be connected to understanding the boundary of the observable universe. Now there is a lot of discussion about blackhole information paradox, many arguments based on assumption that we need to describe something happening inside a black hole. Doesn’t seem logical to me.

    Seems like, by definition, locality vanishes at the event horizon. And if only 1 of a pair of entagled particles escapes the event horizon, then maybe entanglement vanishes too.

    So if the is an identity between locality, entanglement and duality, then one might conclude that event horizons are a source of duality, and then why not complementarity? All parties can imagine how this influences the way we interpret the universe, and how their prior view fits in.

    Have you any thoughts about whether a0 might be an effective acceleration attributed to the observer and relative to something like the cosmological horizon?

    1. In the meantime, I believe that large groups of people can be wrong much better and more persistently than individuals.
      Individuals are more likely to be cautious if their theory puts a contradiction at the beginning. But with a large group, everyone can pass the responsibility to other members of the group.

      1. I do see your point. And in more ways than one, maybe it is all academic. I just find it hard to believe that there is so much out there that is flat out wrong. Seems more likely to me that conclusions are more frequently rather incomplete and subject to misinterpretations.

        1. When I was at school and during my studies, I also thought science is a success story of finding the truth. But after “A Short History of Nearly Everything,” I think it’s just the other way around….

  4. Great stuff. I’m down with the yeah, nay meme at the end. But this seems like much more of a win for Mond. Where the f- is all your dark matter? More of these types of galaxies please.
    Bring it on! maybe?

    1. Way too much snake and way too little debate.
      The articule proves one major flaw of the MOND Dark Matter arguments: they are not falsifiable. No observation can disprove It because their proponents Just arbitrarily adjust dark Matter distribution to match the real world observation.

      On this exact subject: there are dozens of old massive lenticular galaxies whose behaviour is compatible with “normal” distribution of Dark matter, without resort to ad hoc excuses.

      Cosmological coupling looks like a more elegant way to deal with galaxies rotation and universe expansion without resorting to non falsifiable ideas.

      1. Here is something that could be falsifiable in principle. If my suggestion about the solution to the black hole information paradox is correct, then black holes should evaporate much faster than currently expected, maybe at least twice as fast.
        Is there any way to measure this?

  5. I have tried inquiring on X (i.e. Twitter) what would falsify dark matter at least as it relates to the dynamics of galaxies. One response which I liked was that if a property of dark matter that was needed for galaxy-scale physics conflicted with a property required for larger-scale physics.

    Nonetheless, I find it difficult to understand how a galaxy’s dark matter halo, typically more massive than the baryonic content, could still leave galactic dynamics consistent with the RAR, BTFR, MDAR and Renzo’s Rule.

    1. That is a good question, and a rare good answer. Trouble is, we’re already there, and have been for a while – for exactly the reasons you highlight. The MOND-predicted observations you name are not satisfactorily explained by dark matter; they manifestly require properties of dark matter for galaxies that are not the same as what is needed for large scale structure. I’ve been saying this for a quarter century, either people don’t know it, or they are all too happy to come up with unsatisfactory explanations and call it a day.

      1. Would it be possible to point me to a paper or post covering in greater detail the different dark matter properties required for galaxies vs. large scale structure? I may have missed it, but I am thinking that this is not explicitly covered in your many blog posts, such as those for the “laws of nature.”

  6. WordPress is failing hard, so this might appear multiple times or not at all.

    There are comments above saying “you should push harder on this problem for DM” but also “there are plenty of lenticulars for which the DM content is fine.” Both these things can be true, which is why I haven’t pushed harder on it. There are two basic issues. One is that we measure starlight, not stellar mass. So how much dark matter we need depends on what we think the mass-to-light ratio of the stars is. The uncertainty in this allows room to accommodate a wide range of models. Most workers seem to agree that these galaxies are star-dominated, but it depends on just *how* star-dominated they are. Is there room for some dark matter, or none at all? The second issue is what dark matter predicts. I sketched a reasonable expectation above; if that is indeed the correct prediction, then all early type galaxies are a problem for the dark matter picture. But, as I’ve often discussed, lots of models are possible, so rather than there being a testable hypothesis, there is more a spectrum of possibilities from which we tend to select those that are not clearly ruled out. So I think early type galaxies are a genuine problem for the cold dark matter picture, but not as much as other things. That’s an unavoidable judgement call, and one that prevents the community from having a clear set of standards by which to test these hypotheses.

    1. Oh yes I understand. You’re a bit like Sisyphus, and everyday it’s the same dang boulder and the same dang hill. Still we all here in support. Thanks.

  7. Pingback: NGC 1277 é um problema para Mond? – linux-BR.org
  8. Pingback: NGC1277はMONDにとって問題か？ – 世界の話題を日本語でザックリ素早く確認！

    1. >I don’t really understand the difference between
      > dark matter and magic.
      > Can someone explain it to me?

      Dark matter is superstition. Magic is extremely advanced technology. (That’s why some physics papers seem like magic. They’re using high level math spells and skipping steps.)

      2. With hindsight, I can now see that my talk at the MOND40 conference was an attempt to prove that dark matter is astrology – i.e. it depends on the motions of the planets relative to the fixed stars. My main argument was (is) that particle physics still uses the dynamics of the Solar System in 1973, rather than 2023, in much the same way that astrology is left behind by a few thousand years due to the precession of the equinoxes. It may be rubbish, but your interpretation gives me a new line of inquiry into MOND using the (fictional) rotations of frames of reference that are inherent in Special Relativity, due to the impossibility of defining a universal concept of inertial frame.

        1. Discussed here https://arxiv.org/abs/2103.13972
          is the notion that modified gravity theories tend to develop an explicit external field effect, which I interpret as establishing a Machian frame couple with the relative acceleration of the observer.

  10. Dark Matter is when you write up math and equations to explain anything the new data is telling you. Magic is when you do the same, but with words and gestures instead of math. Much less convincing, isn’t it?

    2. I’m not sure it is. As a mathematician, I find that math and equations are basically the same thing as words and gestures. And when I read physics papers I often find it difficult to distinguish the math from magic spells.

      1. With dark matter, I don’t see magic, either.
        But if one achieves excellent results in quantum mechanics with the help of the psi function, that is mathematics. But if one strives for an ontic or epistemic understanding, I feel it is magic.
        It may be that the psi function has nothing to do with our world.

        @JB: This is a second example where a large community is wrong….

        2. Certainly not, quantum physics is excellent science. It’s just the interpretations of which most are kind of magical (many worlds, why sudden wavefunction collapse and so on). The science is really OK, but the scientist bother too little to match up their interpretations with the common sense knowledge that there is a reality, and somewhere it’s hard to believe that God plays dice (schrodinger equation is deterministic), and measurement only causes wavefunction collapse for relatively much larger measurement devices compared to what is measured: wavefunction collapse might be due simply to decoherence when the wavefunction interacts with the measurement device.

          They cannot truly escape knowing somewhere that these things are true, so don’t get annoyed at them – truth will find its way into those scientists too.

    2. Speaking about wide binaries, if Chae and Hernandez are right and wide binaries do signal a deviation from general relativity in the low acceleration regime, does the data distinguish between modified gravity and modified inertial theories?

      1. In principle, maybe. In practice it’ll be challenging – I’m concerned about potential systematics on the main result; distinguishing subtle effects is of course that much harder. FYI, there are flavors of modified inertia in which the EFE is quenched – see https://arxiv.org/abs/2208.07073 – so eventually it should be possible.

  12. Thanks.

    Quantum mechanics has been shown to work of 5% of the universe. Perhaps dark ‘matter’ is something that doesn’t use quantum mechanics. MOND fits that bill, and so do a very few other proposals.

  13. Hi Stacy: Thank you for this post on NGC 1277.

    Getting back to NGC 1277. I like to be able ‘to see’ the problem. Comeron et al. plot the cumulative baryonic mass but not the cumulative dynamical mass. For me that’s a pity as they clearly have the data for both and a plot of both together on the same diagram would have been really helpful. (I’m probably missing something.)

    1. Eliminating Dark Matter as a physical explanation is the “easy” part. Now we need an alternative physical explanation. An alternative mathematical explanation is good, but not good enough.

      1. “Good enough” in regards to what specific question?

        Does any alternate theory help to study the question, why does LCDM seem to require additional free parameters?

        Maybe the initial assumptions make that requirement an inevitable outcome of the model.

        Alternate theories have to do a better job of posing the initial question and making initial assumptions, or they will perhaps end up in the same situation.

        1. That’s quite a deep question, especially as regards the initial assumptions. It is the difference between initial assumptions that chiefly distinguishes MOND from LCDM. In LCDM, one assumes the theory is correct, and therefore has to adjust the input. In MOND, one assumes the input is correct, and therefore one has to adjust the theory. What if both are wrong? What if there is a systematic error in the data, that has not been detected? What if General Relativity has corrupted the data, using the gravitational red-shift of the Milky Way (for example)?

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