Interesting, though doesn't that model predict flat rotation curves, whereas the MW one is declining? So it might have issues explaining the outer, steep slope. This "Scalar/BEC soliton" in Fig. 1 looks interesting in that regard, but I'll have to read this in more detail.

But those alternative DM models don't explain the steep decline in the outskirts. We don't know what mechanism could cause it. Though it is related to the quickly declining Gaia rotation curve, which remains debated and was in itself unexpected. So better measurements might help resolve this.

6/6

We don't know how a core as large as inferred for the inner part of the primordial MW halo could be formed in the cold dark matter paradigm, also because feedback processes should be compensated by the compression effect. Alternative types of DM, like warm or fuzzy DM may help, but only here.

5/6

Rather than finding primordial DM halo in line with expectations from simulations, we infer a profile that is odd in two regards: significantly less centrally concentrated (shallow core), but also dropping faster in the outskirts (steep decline). Much less concentrated than DM-only halos, too.

4/6

To test the robustness of the results, a range of plausible baryonic mass distributions (within observational uncertainties) are used. No matter what empirical baryonic mass distribution is adopted, the inferred primordial halo profiles remain very similar. And odd:

3/6

Cold dark matter only simulations predict a certain halo profile, but once baryons (gas+stars) collapse in the center they pull the DM inward. We invert that baryonic compression process: using the present-day rotation curve and baryonic mass distribution to infer the original DM distribution.

2/6

So, I'd say this could be a dark matter signal ... just like I could be a millionaire after buying a lottery ticket:
In principle not ruled out, I really hope for it to happen, but it is unlikely and every time I've tried thus far it didn't work out.

... but I agree with Stacy that the assumed MW halo is too massive/dense to be realistic. And I'd expect that if you reduce the assumed dark matter density, the same amount of DM needs to generate a stronger signal. Which should increase rather than ease the tension with dwarf galaxy constraints.

The paper itself also mentions that the signal is inconsistent with constraints from dwarf galaxies (which I consider as cleaner targets for such studies). It tries to argue that away by saying that the assumed MW dark matter profile has large uncertainties, ...

There were a few good ones over the years, but I agree, many just make you cringe.

Seems to only apply to the computer science category for now.

This excellent press release about a paper favouring dark matter over MOND came out a few days ago. A great primer to get you excited for dark matter day and the power of tiny galaxies 🔭🧪 bsky.app/profile/8min...

Analyzing the dynamics of dwarf galaxies, she finds they deviate from the Radial Acceleration Relation that was established by more massive galaxies. She also shows that simulated dwarfs in a dark matter framework behave as the observed ones, while MOND expectations disagree
arxiv.org/abs/2510.06905