A conservative assessment of the current constraints on dark matter annihilation from cosmic rays and CMB observations

Abstract

In view of the current interest in combining different observations to constraint annihilating weakly interacting massive particle (WIMP) dark matter (DM), we examine the relation between the Sommerfeld effect at the recombination epoch and in the galactic halo. By considering an up-to-date collection of interpolations of cosmic rays (CRs) lepton data (AMS-02 2014, Fermi and PAMELA), as DM annihilation signals, we show that current CRs measurements and recent Planck 2015 constraints from CMB anisotropies almost overlap for DM masses of the order of few TeV, although great theoretical uncertainties afflict CRs and DM descriptions. Combining CRs fits we obtain proper minimal regions allowed by CMB observations, especially for [Formula: see text] and [Formula: see text] annihilation channels, once assumed viable values of the efficiency factor for energy absorption at recombination: the results are consistent with those obtained by the Planck collaboration but allow a slightly larger overlap between CRs constraints from the lepton sector and CMB. Incoming AMS-02 measurements of CRs antiprotons will help to clarify the conundrum.