Comment on "Is Dark Matter with Long-Range Interactions a Solution to All Small-Scale Problems of ΛCDM Cosmology?"

Abstract

In Phys. Rev. Lett. 109 (2012) 231301, van den Aarssen et al. attempt to solve all the small-scale structure problems in the cold-dark-matter scenario by introducing interaction between the dark-matter particle and an MeV-mass vector boson. In addition, the latter is coupled to ordinary neutrinos, and the neutrino-vector boson coupling constant 10^{-5} < g_nu < 0.1 is required for that purpose. We show that this dark-matter scenario is subject to restrictive constraints from Big Bang Nucleosynthesis.

Figures (1)

• Figure 1: Constraints on $g^{}_\nu$ and $m^{}_V$ from $K$ decays (gray, solid line), $W$ decays (gray, dashed line), and BBN. The two former are reproduced from Ref. Laha:2013xua, and the sample region in Fig. 3 of Ref. Aarssen:2012fx is also presented (light gray). The hashed region bounded by the thick solid curve is excluded by $\Delta N^{}_\nu < 1$ at $95\%$ C.L. Mangano:2011ar. The excluded region will shrink for $\Delta N^{}_\nu < 1.5$ (see, e.g., Ref. Hamann:2011ge), and even further for the "maximally conservative" limit $\Delta N^{}_\nu \lesssim 1.58$ for $m_V > 0.05~{\rm MeV}$.