Shedding light on low-mass subhalo survival and annihilation luminosity with numerical simulations. Issue 1 (13th October 2022)

• Record Type: Journal Article
• Authors: Aguirre-Santaella, Alejandra; Sánchez-Conde, Miguel A; Ogiya, Go; Stücker, Jens; Angulo, Raul E
• Is Part Of: Monthly notices of the Royal Astronomical Society. Volume 518:Issue 1(2023)
• Page Start: 93
• Page End: 110
• Publication Date: 2022-10-13
• Subjects: galaxies: haloes -- cosmology: theory -- cosmology: dark matter -- methods: numerical; Astronomy -- Periodicals; Periodicals; 520.5
• DOI: 10.1093/mnras/stac2921
• Languages: English
• ISSNs: 0035-8711

Abstract

ABSTRACT: In this work, we carry out a suite of specially designed numerical simulations to shed light on dark matter (DM) subhalo survival at mass scales relevant for gamma-ray DM searches, a topic subject to intense debate nowadays. We have employed an improved version of DASH, a GPU N -body code, to study the evolution of low-mass subhaloes inside a Milky-Way-like halo with unprecedented accuracy, reaching solar-mass and sub-parsec resolution. We simulate subhaloes with varying mass, concentration, and orbital properties, and consider the effect of baryons in the host. We analyse the evolution of the bound mass fraction and annihilation luminosity, finding that most subhaloes survive until present, yet losing in some cases more than 99 per cent of their initial mass. Baryons induce a much greater mass-loss, especially when the subhalo orbit is more parallel to the Galactic disc. Many of these subhaloes cross the solar Galactocentric radius, making it easier to detect their annihilation fluxes from Earth. We find subhaloes orbiting a DM-only halo with a pericentre in the solar vicinity to lose 70–90 per cent of their initial annihilation luminosity at present, which increases up to 99 per cent when including baryons. We find a strong relation between subhalo's mass-loss and the effective tidal field at pericentre. Indeed, much of the dependence on all considered parameters can be explained through this single parameter. In addition to shedding light on the survival of low-mass Galactic subhaloes, our results can provide detailed predictions that will aid current and future quests for the nature of DM.