4.6 Article

Baryon-Interacting Dark Matter: heating dark matter and the emergence of galaxy scaling relations

出版社

IOP Publishing Ltd
DOI: 10.1088/1475-7516/2020/06/025

关键词

dark matter theory; rotation curves of galaxies

资金

  1. Agence Nationale de la Recherche (ANR) [ANR-18-CE31-0006]
  2. European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme [834148]
  3. US Department of Energy (HEP) [DE-SC0013528]
  4. NASA ATP grant [80NSSC18K0694]
  5. W.M. Keck Foundation Science and Engineering Grant
  6. National Science Foundation [PHY-1915611]

向作者/读者索取更多资源

The empirical scaling relations observed in disk galaxies remain challenging for models of galaxy formation. The most striking among these is the Mass Discrepancy-Acceleration Relation (MDAR), which encodes both a tight baryonic Tully-Fisher relation (BTFR) and the observed diversity of galaxy rotation curves through the central surface density relation (CSDR). Building on our earlier work [1], we propose here that the MDAR is the result of interactions between baryons and `Baryon-Interacting Dark Matter' (BIDM), which heat up the dark matter. Following a bottom-up, hydrodynamical approach, we find that the MDAR follows if: i) the BIDM equation of state approximates that of an ideal gas; ii) the BIDM relaxation time is order the Jeans time; iii) the heating rate is inversely proportional to the BIDM density. Remarkably, under these assumptions the set of hydrodynamical equations together with Poisson's equation enjoy an anisotropic scaling symmetry. In the BIDM-dominated regime, this gives rise to an enhanced symmetry which fully captures the low-acceleration limit of the MDAR. We then show that, assuming a cored pseudoisothermal profile at equilibrium, this set of equations gives rise to parameters reproducing the MDAR. Specifically, in the flat part of the rotation curve the asymptotic rotational velocity matches the parametric dependence of the BTFR. Moreover, in the central region of high-surface brightness galaxies, the profile reproduces the CSDR. Finally, by studying the time-dependent approach to equilibrium, we derive a global combination of the BTFR and CSDR, which matches the expectations in low surface-brightness galaxies. The form of the heating rate also makes model-independent predictions for various cosmological observables. We argue that our scenario satisfies existing observational constraints, and, intriguingly, offers a possible explanation to the EDGES anomaly.

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