Dark Matter Constraints from a Unified Analysis of Strong Gravitational Lenses and Milky Way Satellite Galaxies

Journal Article · 08 August 2021 · The Astrophysical Journal

DOI: https://doi.org/10.3847/1538-4357/abf9a3 · OSTI ID:1812738

Nadler, Ethan O.  ^[1]; Birrer, Simon  ^[2]; Gilman, Daniel  ^[3]; Wechsler, Risa H.  ^[4]; Du, Xiaolong  ^[5]; Benson, Andrew  ^[5]; Nierenberg, Anna M.  ^[6]; Treu, Tommaso  ^[7]

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1. Stanford Univ., CA (United States). Kavli Institute for Particle Astrophysics & Cosmology; SLAC
2. Stanford Univ., CA (United States). Kavli Institute for Particle Astrophysics & Cosmology
3. Univ. of Toronto, ON (Canada)
4. Stanford Univ., CA (United States). Kavli Institute for Particle Astrophysics & Cosmology ; SLAC National Accelerator Lab., Menlo Park, CA (United States)
5. Carnegie Observatories, Pasadena, CA (United States)
6. Univ. of California, Merced, CA (United States)
7. Occidental College, Los Angeles, CA (United States)

Joint analyses of small-scale cosmological structure probes have been relatively unexplored yet promise to advance measurements of microphysical dark matter properties using heterogeneous data. Here, we present a multidimensional analysis of dark matter substructure using strong gravitational lenses and the Milky Way (MW) satellite galaxy population, accounting for degeneracies in model predictions and using covariances in the constraining power of these individual probes for the first time. We simultaneously infer the projected subhalo number density and the half-mode mass describing the suppression of the subhalo mass function in thermal relic warm dark matter (WDM), $$M_{\mathrm{hm}}$$, using the semianalytic model \texttt{Galacticus} to connect the subhalo population inferred from MW satellite observations to the strong lensing host halo mass and redshift regime. Combining MW satellite and strong lensing posteriors in this parameter space yields $$M_{\mathrm{hm}}<10^{7.0}\ M_{\mathrm{\odot}}$$ (WDM particle mass $$m_{\mathrm{WDM}}>9.7\ \mathrm{keV}$$) at $$95\%$$ confidence and disfavors $$M_{\mathrm{hm}}=10^{7.4}\ M_{\mathrm{\odot}}$$ ($$m_{\mathrm{WDM}}=7.4\ \mathrm{keV}$$) with a 20:1 marginal likelihood ratio, improving limits on $$m_{\mathrm{WDM}}$$ set by the two methods independently by $$\sim 30\%$$. These results are marginalized over the line-of-sight contribution to the strong lensing signal, the mass of the MW host halo, and the efficiency of subhalo disruption due to baryons and are robust to differences in the disruption efficiency between the MW and strong lensing regimes at the $$\sim 10\%$$ level. This work paves the way for unified analyses of next-generation small-scale structure measurements covering a wide range of scales and redshifts.

• Research Organization: SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States)
• Sponsoring Organization: USDOE Office of Science (SC)
• Grant/Contract Number: AC02-76SF00515
• OSTI ID: 1812738
• Journal Information: The Astrophysical Journal, Journal Name: The Astrophysical Journal Journal Issue: 1 Vol. 917; ISSN 0004-637X
• Publisher: IOP PublishingCopyright Statement
• Country of Publication: United States
• Language: English