Are there any extragalactic high speed dark matter particles in the Solar neighborhood?

Abstract

We use the APOSTLE suite of cosmological hydrodynamical simulations of the Local Group to examine the high speed tail of the local dark matter velocity distribution in simulated Milky Way analogues. The velocity distribution in the Solar neighborhood is well approximated by a generalized Maxwellian distribution sharply truncated at a well-defined maximum ``escape" speed. The truncated generalized Maxwellian distribution accurately models the local dark matter velocity distribution of all our Milky Way analogues, with no evidence for any separate extragalactic high-speed components. The local maximum speed is well approximated by the terminal velocity expected for particles able to reach the Solar neighborhood in a Hubble time from the farthest confines of the Local Group. This timing constraint means that the local dark matter velocity distribution is unlikely to contain any high-speed particles contributed by the Virgo Supercluster ``envelope", as argued in recent works. Particles in the Solar neighborhood with speeds close to the local maximum speed can reach well outside the virial radius of the Galaxy, and, in that sense, belong to the Local Group envelope posited in earlier work. The local manifestation of such envelope is thus not a distinct high-speed component, but rather simply the high-speed tail of the truncated Maxwellian distribution.

arXiv comment16 pages, 8 figures. To be submitted to JCAP

References in corpus (32)

• A Universal Density Profile from Hierarchical Clustering
• Seven-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Cosmological Interpretation
• The Structure of Cold Dark Matter Halos
• Particle Dark Matter: Evidence, Candidates and Constraints
• Supersymmetric Dark Matter
• The EAGLE project: Simulating the evolution and assembly of galaxies and their environments
• GADGET: A code for collisionless and gasdynamical cosmological simulations
• The EAGLE simulations of galaxy formation: calibration of subgrid physics and model variations
• Non-Baryonic Dark Matter - Observational Evidence and Detection Methods
• Baryon effects on the internal structure of LCDM halos in the EAGLE simulations
• The Milky Way total mass profile as inferred from Gaia DR2
• The APOSTLE project: Local Group kinematic mass constraints and simulation candidate selection
• Bent by baryons: the low mass galaxy-halo relation
• A new way of setting the phases for cosmological multi-scale Gaussian initial conditions
• Simulated Milky Way analogues: implications for dark matter direct searches
• Assessing Astrophysical Uncertainties in Direct Detection with Galaxy Simulations
• The impact of baryons on the direct detection of dark matter
• Implications of hydrodynamical simulations for the interpretation of direct dark matter searches
• The highest-speed local dark matter particles come from the Large Magellanic Cloud
• Magellanic satellites in $\Lambda$CDM cosmological hydrodynamical simulations of the Local Group
• The dark matter component of the Gaia radially anisotropic substructure
• Direct detection of non-galactic light dark matter
• The impact of the Large Magellanic Cloud on dark matter direct detection signals
• The missing dwarf galaxies of the Local Group
• Extragalactic dark matter and direct detection experiments
• On the direct detection of extragalactic WIMPs
• Dark matter capture by the Sun: revisiting velocity distribution uncertainties
• Effects on the local dark matter distribution due to the Large Magellanic Cloud
• A unified scenario for the origin of spiral and elliptical galaxy structural scaling laws
• Informing dark matter direct detection limits with the ARTEMIS simulations
• Enhanced prospects for direct detection of inelastic dark matter from a non-galactic diffuse component
• The local dark matter distribution in self-interacting dark matter halos