Decays and annihilation of galactic dark matter: determine $D$-, $J_s$-, $J_p$- and $J_d$-factors with dark matter profiles inferred from GravSphere fit to stellar observations

Abstract

Dark matter mass density profiles and velocity distributions for a set of dwarf spheroidal galaxies (dSphs) have recently been obtained (F.Bezrukov, D.Gorbunov, E.Koreshkova arXiv:2412.20585) by performing a multi-parametric fit to the stellar observations with the help of the GravSphere which solves the Jeans equation. We use these results to calculate the geometrical factors for estimation of the fluxes of cosmic rays expected from decay ($D$-factor) and annihilation ($J_s$-, $J_p$- and $J_d$-factors for $s$-, $p$- and $d$- wave processes) of dark matter particles in galaxies. The general novelty is the account for a possible anisotropy in velocities of dark matter particles. On the basis of this analysis we present empirical scaling approximations to these factors as functions of typical observables: distance to the galaxy $d$, it's half-radius $r_h$ and line-of-sight stellar velocity dispersion $\sigma_{LOS}$. They can be applied to any galaxy, and for $D$- and $J_s$-factors we refine the estimates of (Andrew B. Pace, Louis E. Strigari arXiv:1802.06811): the shifts in the central values remain within 1-2$\sigma$ error bars.