Impact of baryons on the population of Galactic subhalos and implications for dark matter searches

Abstract

We have used Auriga --a set of state-of-the-art cosmological hydrodynamical simulations of Milky Way-size systems-- to study the impact of baryons on the Galactic subhalo population. A DM-only run counterpart of Auriga allows us to compare results with and without baryons. We repopulate the original suites with low-mass subhalos orders of magnitude lighter than the mass resolution limit, starting from a detailed characterization of Auriga data in the well-resolved subhalo mass range. The survival of low-mass subhalos to tidal forces is unclear and under debate nowadays, thus in our study we stay agnostic and consider two different levels of subhalo resilience to tidal stripping ('fragile' and 'resilient' subhalos). We find baryons to alter the Galactic substructure significantly, by decreasing its overall abundance by a factor $\sim 2.4$ (fragile) and $\sim 1.9$ (resilient) and subhalo concentration --here defined in terms of maximum circular velocity-- by $\sim 1.5$ with respect to the DM-only scenario. This has important consequences for indirect searches of DM. As an example, we investigated the case of using unidentified gamma-ray sources to set constraints on the DM particle properties, assuming some of them may be dark satellites. Our results show the importance of including baryons to properly characterize the Galactic subhalo population, as well as to propose the most optimal subhalo search strategies, not only via its potential DM annihilation products but also through their gravitational signatures (e.g.~stellar streams, strong lensing).

25 pages, 18 figures

References in corpus (29)

• Array Programming with NumPy
• The Astropy Project: Sustaining and Growing a Community-oriented Open-source Project and the Latest Major Release (v5.0) of the Core Package
• Concentration, Spin and Shape of Dark Matter Haloes as a Function of the Cosmological Model: WMAP1, WMAP3 and WMAP5 results
• Dark matter and cosmic structure
• Disruption of Dark Matter Substructure: Fact or Fiction?
• Dark Matter Substructure in Numerical Simulations: A Tale of Discreteness Noise, Runaway Instabilities, and Artificial Disruption
• Bent by baryons: the low mass galaxy-halo relation
• Dark matter local density determination: recent observations and future prospects
• An excess of small-scale gravitational lenses observed in galaxy clusters
• The Global Dynamical Atlas of the Milky Way mergers: Constraints from Gaia EDR3 based orbits of globular clusters, stellar streams and satellite galaxies
• Forensics of Subhalo-Stream Encounters: The Three Phases of Gap Growth
• The asymptotic tidal remnants of cold dark matter subhalos
• Determining the full satellite population of a Milky Way-mass halo in a highly resolved cosmological hydrodynamic simulation
• The tidal evolution of dark matter substructure -- I. Subhalo density profiles
• LCDM halo substructure properties revealed with high resolution and large volume cosmological simulations
• Unidentified Gamma-ray Sources as Targets for Indirect Dark Matter Detection with the Fermi-Large Area Telescope
• Tidal Stripping in the Adiabatic Limit
• Spectral and spatial analysis of the dark matter subhalo candidates among Fermi Large Area Telescope unidentified sources
• SatGen -- II. Assessing the impact of a disc potential on subhalo populations
• The Turn-Down of the Baryonic Tully-Fisher Relation and Changing Baryon Fractions at Low Galaxy Masses
• Baryonic effects on the detectability of annihilation radiation from dark matter subhaloes around the Milky Way
• The dark side of FIRE: predicting the population of dark matter subhaloes around Milky Way-mass galaxies
• Shedding light on low-mass subhalo survival and annihilation luminosity with numerical simulations
• Investigating the detection of dark matter subhalos as extended sources with Fermi-LAT
• Sensitivity of the Cherenkov Telescope Array to dark subhalos
• The Impact of Molecular Hydrogen Cooling on the Galaxy Formation Threshold
• Spatial extension of dark subhalos as seen by Fermi-LAT and implications for WIMP constraints
• 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

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