Azimuthal asymmetry in cosmic-ray boosted dark matter flux

Abstract

Light halo dark matter (DM) particles up-scattered by high-energy cosmic rays (referred to as CRDM) can be energetic and become detectable at conventional DM and neutrino experiments. We show that the CRDM flux has a novel and detectable morphological feature. Unlike most of the recently proposed boosted DM (BDM) models which predict azimuthally symmetric DM fluxes around the Galactic Center, the CRDM flux breaks the azimuthal symmetry significantly. Using cosmic-ray electron distribution in the whole Galaxy and optimized search region in the sky according to the morphology of the CRDM flux, we derive so far the most stringent constraints on the DM-electron scattering cross section from the Super-Kamiokande (SK) IV data, which improves the previous constraints from the SK-IV full-sky data by more than an order of magnitude. Based on the improved constraints, we predict that the azimuthal symmetry-breaking effect can be observed in the future Hyper-Kamiokande experiment at ∼ 3σ level.

Blazar boosted Dark Matter -- direct detection constraints on $σ_{eχ}$ : Role of energy dependent cross sections

“…It would also be an incorrect approximation to make, notably in scenarios where a significant DM flux becomes relativistic after being scattered by energetic particles. Some of the previously mentioned works [8,[17][18][19]26] for cosmic ray boosted DM, have already discovered that the limits for energy-dependent cross-section differ by orders of magnitude from those obtained under the assumption of a constant cross section.…”

“…The reach of these experiments has been extended to DM masses well below 1 GeV in recent years, thanks to the novel idea of boosting the halo DM through its interaction with the SM particles via cosmic rays [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21], primordial black holes [22,23], diffuse Supernova Neutrino Background (DSNB) [11][12][13][14][15], and blazars [24,25]. Despite the fact that the boosted DM flux is substan-tial and DM particles are (semi)relativistic, the sensitivity is achieved at larger cross sections because the upscattered subcomponent flux is significantly lower than the galactic DM population.…”