Blazar boosted Dark Matter -- direct detection constraints on $\sigma_{e\chi}$ : Role of energy dependent cross sections

TL;DR

This paper investigates how relativistic electrons from blazar jets can boost dark matter particles, enabling new constraints on the DM-electron scattering cross section for low-mass DM, with energy-dependent effects significantly strengthening previous limits.

Contribution

It introduces energy-dependent scattering cross sections into the analysis of boosted dark matter constraints from blazar jets, improving the limits by orders of magnitude.

Findings

Energy dependence of the scattering matrix significantly alters constraints.

Revised limits are orders of magnitude stronger than constant cross section assumptions.

Constraints are evaluated for different dark matter density spike profiles.

Abstract

Elastic collisions with relativistic electrons from the blazar's jet can accelerate dark matter (DM) particles in the DM spike surrounding the supermassive black hole at its center. This can allow one to set stringent limits on the DM-electron scattering cross section ($\bar{\sigma}_{e\chi}$) for DM masses less than 100 MeV. We consider DM particles boosted by energetic electrons in the jets of the blazars TXS 0506+056 and BL Lacertae. Both vector and scalar mediators for the scattering of electron and electrophilic fermionic DM are studied. We highlight that the ensuing energy dependency of the S-matrix for the corresponding Lorentz structure of the vertex significantly modifies the constraints. We find that the revised exclusion limits are orders of magnitude stronger than the equivalent results for the simple constant cross section assumption. Our limits are also assessed for the less cuspy spike.