# King's College London

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

Research output: Contribution to journalArticlepeer-review

James Alvey, Nashwan Sabti, Victoria Tiki, Diego Blas, Kyrylo Bondarenko, Alexey Boyarsky, Miguel Escudero, Malcolm Fairbairn, Matthew Orkney, Justin I. Read

Original language English 1188-1201 14 MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY 501 1 https://doi.org/10.1093/mnras/staa3640 1 Feb 2021 Link to publication in Scopus

## Bibliographical note

Dwarf spheroidal galaxies are excellent systems to probe the nature of fermionic dark matter due to their high observed dark matter phase-space density. In this work, we review, revise, and improve upon previous phase-space considerations to obtain lower bounds on the mass of fermionic dark matter particles. The refinement in the results compared to previous works is realized particularly due to a significantly improved Jeans analysis of the galaxies. We discuss two methods to obtain phase-space bounds on the dark matter mass, one model-independent bound based on Pauli's principle, and the other derived from an application of Liouville's theorem. As benchmark examples for the latter case, we derive constraints for thermally decoupled particles and (non-)resonantly produced sterile neutrinos. Using the Pauli principle, we report a model-independent lower bound of $m \ge 0.18\, \mathrm{keV}$ at 68 per cent CL and $m \ge 0.13\, \mathrm{keV}$ at 95 per cent CL. For relativistically decoupled thermal relics, this bound is strengthened to $m \ge 0.59\, \mathrm{keV}$ at 68 per cent CL and $m \ge 0.41\, \mathrm{keV}$ at 95 per cent CL, while for non-resonantly produced sterile neutrinos the constraint is $m \ge 2.80\, \mathrm{keV}$ at 68 per cent CL and $m \ge 1.74\, \mathrm{keV}$ at 95 per cent CL. Finally, the phase-space bounds on resonantly produced sterile neutrinos are compared with complementary limits from X-ray, Lyman α, and big bang nucleosynthesis observations.