Detecting dark matter subhalos in the Galactic plane with the Cherenkov Telescope Array Observatory

Authors:
Open Access
Publisher website
Google Scholar
Abstract
Numerous observations confirm the existence of dark matter (DM) at astrophysical and cosmological scales, yet the fundamental nature of this elusive component of our Universe remains unknown. Theory and simulations of Galaxy formation predict that DM should cluster on small scales in bound structures called subhalos or DM clumps. While the most massive DM subhalos host baryonic matter and are observed as dwarf galaxies of the Milky Way (MW), less massive, unpopulated subhalos could be abundant in the Galaxy as well and yield high-energy gamma rays as final products of DM annihilation. Recently, it has been highlighted that the brightest halos should also have a sizeable extension in the sky. In this study, we examine the prospects offered by the Cherenkov Telescope Array Observatory (CTAO), a next-generation gamma-ray instrument, for detecting and characterizing such objects. Previous studies have primarily focused on high-latitude observations; here, we assess the potential impact of the CTAO’s Galactic Plane Survey, which will provide unprecedentedly deep survey data for the inner five degrees of the Galactic plane. Our modeling accounts for tidal effects on the subhalo population, examining the conditions under which DM subhalos can be detected and distinguished from conventional astrophysical sources. We find that regions a few degrees above or below the Galactic plane offer the highest likelihood for DM subhalo detection. For an individual subhalo—the brightest from among various realizations of the MW subhalo population—we find that detection at the 5 σ level is achievable for an annihilation cross section of ⟨ σ v ⟩ ∼ 3 × 10 − 25 cm 3 / s for TeV-scale DM annihilating into b b ¯ . For a full population study, depending on the distribution and luminosity model of Galactic subhalos, still unconstrained cross sections in the range ⟨ σ v ⟩ ∼ 10 − 23 – 10 − 22 cm 3 / s for TeV DM candidates are necessary for the brightest subhalos to be detected.
All Related Versions
Funding Information
  • Agence Nationale de la Recherche (ANR-19-CE31-0005-01)
  • Horizon 2020 Framework Programme (101017536, 101081355)
  • Government of Canada
  • Ministry of Colleges and Universities
  • European Union from the European Regional Development Fund
  • Republic of Slovenia

This publication has 129 references indexed in Scilit: