Dark matter constraints from dwarf galaxies with data-driven J-factors

Abstract

We present an updated analysis of the gamma-ray flux from the directions of classical dwarf spheroidal galaxies, deriving new constraints on WIMP dark matter (DM) annihilation using a decade of Fermi-LAT data. Among the major novelties, we infer the dwarfs' J-factors by including new observations without imposing any a priori parametric profile for the DM distribution. While statistically compatible with results obtained from more conventional parameterisations, this procedure reduces the theoretical bias imposed on the data. Furthermore, we retain the full data-driven shape of the J-factors' empirical probability distributions when setting limits on DM, without imposing log-normality as is typically done. In conjunction with the data-driven J-factors, we improve on a new method for estimating the probability distribution function of the astrophysical background at the dwarf position [1], fully profiling over background uncertainties. We show that, for most “classical” dwarfs, the background systematic uncertainty dominates over the uncertainty on their J-factors. {Raw distributions of J- and D-factors (the latter being the analogous of J-factors for decaying DM) are available upon request.}

Andromeda XXI – a dwarf galaxy in a low-density dark matter halo

“…The reasons for shifting away from the 'non-parametric' dark matter mass profile from Read & Steger (2017) is twofold. Firstly, for ∼1000+ tracers, the results from using the NFW profile and the 'non-parametric' profile agree within their respective 68% confidence intervals Alvarez et al (2020), yet the NFW model fit parameters are more cosmologically useful (Read et al 2018;Read & Erkal 2019). Secondly, in the absence of data, the default priors on the non-parametric mass profile favour a high density in the centre that falls very steeply outwards, inconsistent with expectations in most popular cosmological models.…”

New constraints on the mass of fermionic dark matter from dwarf spheroidal galaxies

“…McConnachie 2012; Alvarez et al (2020). We expect that the galaxies with the most cusp-like profiles will have the largest dark matter phase-space densities and are therefore the objects of most significance to the bound presented in this work.…”

AMS-02 antiprotons and dark matter: Trimmed hints and robust bounds

“…The red contour is the 95% CL contour of the fit to the Galactic Center excess reported in [76] for the same annihilation channel. We also display bounds from different samples dwarf spheroidal galaxies (dSph) derived with a new data-driven method [77] (green solid line), with traditional template-fitting strategies [78] (green dashed line), and by combining Fermi-LAT and ground-based telescopes data [79] (Glory Duck project, green dot-dashed line). The yellow band are radio constraints derived from the EMU survey [80].…”

“…or less aggressive assumptions entering its derivation. We illustrate that by plotting: i) A rather conservative bound, obtained by limiting the study to four classical, kinematically well-determined dSph, and using a data-driven approach for both DM profiles and astrophysical background determination (solid green curve, from [77]; see also [84] for methodological details). ii) The bound published by the Fermi-LAT Collaboration [78], and performed with traditional template-fitting techniques of the data in a rather large region of interest around the target.…”