Warm dark matter constraints using Milky Way satellite observations and subhalo evolution modeling

• DOI: 10.48550/arxiv.2111.13137
• Publication Date: 2022-12-27
• Authors: Ariane Dekker; Shin’ichiro Ando; Camila A. Correa; Kenny C. Y. Ng
• Keywords: Cosmology and Nongalactic Astrophysics (astro-ph.CO); FOS: Physical sciences; 530; 01 natural sciences; 520; High Energy Physics - Phenomenology; High Energy Physics - Phenomenology (hep-ph); 13. Climate action; 0103 physical sciences; Astrophysics - Cosmology and Nongalactic Astrophysics

14 pages, 8 figures; Comments welcome. v2: Accepted for publication in PRD<br/>Warm dark matter (WDM) can potentially explain small-scale observations that currently challenge the cold dark matter (CDM) model, as warm particles suppress structure formation due to free-streaming effects. Observing small-scale matter distribution provides a valuable way to distinguish between CDM and WDM. In this work, we use observations from the Dark Energy Survey and PanSTARRS1, which observe 270 Milky-Way satellites after completeness corrections. We test WDM models by comparing the number of satellites in the Milky Way with predictions derived from the Semi-Analytical SubHalo Inference ModelIng (SASHIMI) code, which we develop based on the extended Press-Schechter formalism and subhalos' tidal evolution prescription. We robustly rule out WDM with masses lighter than 4.4 keV at 95% confidence level for the Milky-Way halo mass of $10^{12} M_\odot$. The limits are a weak function of the (yet uncertain) Milky-Way halo mass, and vary as $m_{\rm WDM}>3.6$-$5.1$ keV for $(0.6$-$2.0) \times 10^{12} M_\odot$. For the sterile neutrinos that form a subclass of WDM, we obtain the constraints of $m_{ν_s}>11.6$ keV for the Milky-Way halo mass of $10^{12} M_{\odot}$. These results based on SASHIMI do not rely on any assumptions of galaxy formation physics or are not limited by numerical resolution. The models, therefore, offer a robust and fast way to constrain the WDM models. By applying a satellite forming condition, however, we can rule out the WDM mass lighter than 9.0 keV for the Milky-Way halo mass of $10^{12} M_\odot$.<br/>