Precise constraints on the dark matter content of Milky Way dwarf galaxies for gamma-ray experiments

Abstract

We examine the prospects for detecting γ-rays from dark matter annihilation in the six most promising dwarf spheroidal (dSph) satellite galaxies of the Milky Way. We use recently-measured velocity dispersion profiles to provide a systematic investigation of the dark matter mass distribution of each galaxy, and show that the uncertainty in the γ-ray flux from mass modeling is less than a factor of ∼ 5 for each dSph if we assume a smooth NFW profile. We show that Ursa Minor and Draco are the most promising dSphs for γ-ray detection with GLAST and other planned observatories. For each dSph, we investigate the flux enhancement resulting from halo substructure, and show that the enhancement factor relative to a smooth halo flux cannot be greater than about 100. This enhancement depends very weakly on the lower mass cut-off scale of the substructure mass function. While the amplitude of the expected flux from each dSph depends sensitively on the dark matter model, we show that the flux ratios between the six Sphs are known to within a factor of about 10. The flux ratios are also relatively insensitive to the current theoretical range of cold dark matter halo central slopes and substructure fractions.

Optimized Dark Matter Searches in Deep Observations of Segue 1 with MAGIC

“…Considering the energy range for which the MAGIC telescopes are sensitive to gamma rays, we search for DM particles of mass m χ between 100 GeV and 10 TeV for annihilation scenarios and between 200 GeV and 20 TeV for the decaying DM. Furthermore, all of the results are produced without the assumptions of some additional boosts, either from the presence of substructures [44] or from quantum effects [45]. photon spectrum and the derived constraints can be noticed: the strongest bound corresponds to the τ + τ − channel ( σ ann v ∼ 1.2×10 −24 cm 3 s −1 ), as it produces photons whose spectrum is the hardest at energies for which the sensitivity of MAGIC is at peak.…”

A unified model for the spatial and mass distribution of subhaloes

“…Strigari et al 2007;Anderhalden & Diemand 2013;Sánchez-Conde & Prada 2014) in that we start from the infall mass to infer the density profile, rather than from the current mass which has been affected by tidal stripping. The concentration of subhaloes plays a vital role in this estimate, with lower concentrations leading to lower boost factors.…”

What can Gaia (with Thirty Meter Telescope) say about the Sculptor Dwarf's Core?

“…We have also tried including estimates of r 0 and ρ 0 from CDM simulations, as summarized in Ref. [18]. With these constraints we find that Gaia can determine γ(r 1/2 ) with a precision of 0.57.…”

“…ρ s (R) is the 3d stellar density at a radius R, not just the density of the stars in the catalog, which is taken to follow a King profile [17] with core radius r k = 0.28 kpc and tidal radius r t = 1.63 kpc [18]. The observed line of sight, radial and tangential dispersions can be found by integrating (6) over the line of sight…”

“…The derivatives with respect to the parameters θ a are evaluated at the fiducial NFW model [18] a = b = 1, c = 3, r 0 = 0.5, ρ 0 = 8, β = 0 (9) where r 0 and ρ 0 are measured in units of kpc and 10 7 M /kpc 3 respectively.…”