Baryonic effects on the detectability of annihilation radiation from dark matter subhaloes around the Milky Way

Abstract

We use six, high-resolution $\Lambda$CDM simulations of galaxy formation to study how emission from dark matter annihilation is affected by baryonic processes. These simulations produce isolated, disc-dominated galaxies with structure, stellar populations, and stellar and halo masses comparable to those of the Milky Way. They resolve dark matter structures with mass above $\sim 10^6$ ${\mathrm{M}}_{\odot }$ and are each available in both full-physics and dark-matter-only versions. In the full-physics case, formation of the stellar galaxy enhances annihilation radiation from the dominant smooth component of the galactic halo by a factor of three, and its central concentration increases substantially. In contrast, subhalo fluxes are $reduced$ by almost an order of magnitude, partly because of changes in internal structure, partly because of increased tidal effects; they drop relative to the flux from the smooth halo by 1.5 orders of magnitude. The expected flux from the brightest subhalo is four orders of magnitude below that from the smooth halo, making it very unlikely that any subhalo will be detected before robust detection of the inner Galaxy. We use recent simulations of halo structure across the full $\Lambda$CDM mass range to extrapolate to the smallest (Earth-mass) subhaloes, concluding, in contrast to earlier work, that the total annihilation flux from Milky Way subhaloes will be less than that from the smooth halo, as viewed both from the Sun and by a distant observer. Fermi-LAT may marginally resolve annihilation radiation from the very brightest subhaloes, which, typically, will contain stars.

accepted (MNRAS)

References in corpus (12)

• The EAGLE project: Simulating the evolution and assembly of galaxies and their environments
• The spectrum of isotropic diffuse gamma-ray emission between 100 MeV and 820 GeV
• The Auriga Project: the properties and formation mechanisms of disc galaxies across cosmic time
• Searching for Dark Matter Annihilation in Recently Discovered Milky Way Satellites with Fermi-LAT
• Dark matter and cosmic structure
• Baryon effects on the internal structure of LCDM halos in the EAGLE simulations
• A blueprint for detecting supersymmetric dark matter in the Galactic halo
• Constraints on the Galactic Halo Dark Matter from Fermi-LAT Diffuse Measurements
• Origin of chemically distinct discs in the Auriga cosmological simulations
• Shaken and Stirred: The Milky Way's Dark Substructures
• Properties of HI discs in the Auriga cosmological simulations
• Dark matter halo shapes in the Auriga simulations

Cited by in corpus (14)

• Tidal Stripping in the Adiabatic Limit
• Prompt cusps and the dark matter annihilation signal
• TeV Dark Matter Searches in the Extragalactic Gamma-Ray Sky
• Shedding light on low-mass subhalo survival and annihilation luminosity with numerical simulations
• Dark matter annihilation and the Galactic Centre Excess
• Velocity-dependent annihilation radiation from dark matter subhalos in cosmological simulations
• Searching for dark-matter induced neutrino signals in dwarf spheroidal galaxies using 10 years of IceCube public data
• Using $\gamma$-ray observations of dwarf spheroidal galaxies to test the possible common origin of the W-boson mass anomaly and the GeV $\gamma$-ray/antiproton excesses
• Cosmological Zoom-In Simulations of Milky Way Host Mass Dark Matter Halos with a Blue-Tilted Primordial Power Spectrum
• The Effects of $\Lambda$CDM Dark Matter Substructure on the Orbital Evolution of Star Clusters
• The influence of baryons on low-mass haloes
• The viability of low-mass subhaloes as targets for gamma-ray dark matter searches
• New insights on low-mass dark matter subhalo tidal tracks via numerical simulations
• Impact of baryons on the population of Galactic subhalos and implications for dark matter searches