Joint constraints on thermal relic dark matter from strong gravitational lensing, the Ly α forest, and Milky Way satellites

Wolfgang Enzi*, Riccardo Murgia, Oliver Newton, Simona Vegetti*, Carlos Frenk, Matteo Viel, Marius Cautun, Christopher D. Fassnacht, Matt Auger, Giulia Despali, John McKean, Léon V. E. Koopmans, Mark Lovell

*Corresponding author for this work

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We derive joint constraints on the warm dark matter (WDM) half-mode scale by combining the analyses of a selection of astrophysical probes: strong gravitational lensing with extended sources, the Ly α forest, and the number of luminous satellites in the Milky Way. We derive an upper limit of λhm = 0.089 Mpc h-1 at the 95 per cent confidence level, which we show to be stable for a broad range of prior choices. Assuming a Planck cosmology and that WDM particles are thermal relics, this corresponds to an upper limit on the half-mode mass of Mhm < 3 × 107 M h-1, and a lower limit on the particle mass of mth > 6.048 keV, both at the 95 per cent confidence level. We find that models with λhm > 0.223 Mpc h-1 (corresponding to mth > 2.552 keV and Mhm < 4.8 × 108 M h-1) are ruled out with respect to the maximum likelihood model by a factor ≤1/20. For lepton asymmetries L6 > 10, we rule out the 7.1 keV sterile neutrino dark matter model, which presents a possible explanation to the unidentified 3.55 keV line in the Milky Way and clusters of galaxies. The inferred 95 percentiles suggest that we further rule out the ETHOS-4 model of self-interacting DM. Our results highlight the importance of extending the current constraints to lower half-mode scales. We address important sources of systematic errors and provide prospects for how the constraints of these probes can be improved upon in the future.
Original languageEnglish
Pages (from-to)5848-5862
Number of pages15
JournalMonthly Notices of the Royal Astronomical Society
Early online date10-Jul-2021
Publication statusPublished - 1-Oct-2021


  • gravitational lensing: strong
  • Galaxy: structure
  • galaxies: haloes
  • intergalactic medium
  • galaxies: structure
  • dark matter
  • Astrophysics - Cosmology and Nongalactic Astrophysics

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