Milky Way Satellite Census. IV. Constraints on Decaying Dark Matter from Observations of Milky Way Satellite Galaxies
S. Mau, E. O. Nadler, R. H. Wechsler, A. Drlica-Wagner, K. Bechtol, G. Green, D. Huterer, T. S. Li, Y. -Y. Mao, C. E. Martínez-Vázquez, M. McNanna, B. Mutlu-Pak… 展开作者
S. Mau, E. O. Nadler, R. H. Wechsler, A. Drlica-Wagner, K. Bechtol, G. Green, D. Huterer, T. S. Li, Y. -Y. Mao, C. E. Martínez-Vázquez, M. McNanna, B. Mutlu-Pakdil, A. B. Pace, A. Peter, A. H. Riley, L. Strigari, M. -Y. Wang, M. Aguena, S. Allam, J. Annis, D. Bacon, E. Bertin, S. Bocquet, D. Brooks, D. L. Burke, A. Carnero Rosell, M. Carrasco Kind, J. Carretero, M. Costanzi, M. Crocce, M. E. S. Pereira, T. M. Davis, J. De Vicente, S. Desai, P. Doel, I. Ferrero, B. Flaugher, J. Frieman, J. García-Bellido, M. Gatti, G. Giannini, D. Gruen, R. A. Gruendl, J. Gschwend, G. Gutierrez, S. R. Hinton, D. L. Hollowood, K. Honscheid, D. J. James, K. Kuehn, O. Lahav, M. A. G. Maia, J. L. Marshall, R. Miquel, J. J. Mohr, R. Morgan, R. L. C. Ogando, F. Paz-Chinchón, A. Pieres, M. Rodriguez-Monroy, E. Sanchez, V. Scarpine, S. Serrano, I. Sevilla-Noarbe, E. Suchyta, G. Tarle, C. To, D. L. Tucker, J. Weller
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26 pages, 11 figures, 1 table. Updated to published version
We use a recent census of the Milky Way (MW) satellite galaxy population to constrain the lifetime of particle dark matter (DM). We consider two-body decaying dark matter (DDM) in which a heavy DM particle decays with lifetime $τ$ comparable to the age of the Universe to a lighter DM particle (with mass splitting $ε$) and to a dark radiation species. These decays impart a characteristic "kick velocity," $V_{\mathrm{kick}}=εc$, on the DM daughter particles, significantly depleting the DM content of low-mass subhalos and making them more susceptible to tidal disruption. We fit the suppression of the present-day DDM subhalo mass function (SHMF) as a function of $τ$ and $V_{\mathrm{kick}}$ using a suite of high-resolution zoom-in simulations of MW-mass halos, and we validate this model on new DDM simulations of systems specifically chosen to resemble the MW. We implement our DDM SHMF predictions in a forward model that incorporates inhomogeneities in the spatial distribution and detectability of MW satellites and uncertainties in the mapping between galaxies and DM halos, the properties of the MW system, and the disruption of subhalos by the MW disk using an empirical model for the galaxy--halo connection. By comparing to the observed MW satellite population, we conservatively exclude DDM models with $τ< 18\ \mathrm{Gyr}$ ($29\ \mathrm{Gyr}$) for $V_{\mathrm{kick}}=20\ \mathrm{km}\, \mathrm{s}^{-1}$ ($40\ \mathrm{km}\, \mathrm{s}^{-1}$) at $95\%$ confidence. These constraints are among the most stringent and robust small-scale structure limits on the DM particle lifetime and strongly disfavor DDM models that have been proposed to alleviate the Hubble and $S_8$ tensions.
DELVE Milky Way Satellite Galaxy Census I: Satellite Population and Survey Selection Function in DES, DELVE, and Pan-STARRS
Kavli Institute for Cosmological Physics, University of Chicago（芝加哥大学卡弗里宇宙物理研究所）；Department of Physics, University of Chicago（芝加哥大学物理系）；NSF-Simons AI Institute for the Sky (SkAI)（美国国家科学基金会-西蒙斯天空人工智能研究所）；Fermi National Accelerator Laboratory（费米国家加速器实验室）；Department of Astronomy and Astrophysics, University of Chicago（芝加哥大学天文与天体物理系）；Department of Astronomy, University of Virginia（弗吉尼亚大学天文学系）；Department of Astronomy, Yale University（耶鲁大学天文学系）
研究通过分析DES、DELVE和Pan-STARRS三个巡天数据集，量化 Milky Way 卫星星系的探测效率，确定其亮度函数、径向分布和大小-亮度关系，并发现观测选择效应对卫星人口的影响。
