Spherical Jeans analysis for dark matter indirect detection in dwarf spheroidal galaxies - Impact of physical parameters and triaxiality

Abstract

Dwarf spheroidal (dSph) galaxies are among the most promising targets for the indirect detection of dark matter (DM) from annihilation and/or decay products. Empirical estimates of their DM content - and hence the magnitudes of expected signals - rely on inferences from stellar-kinematic data. However, various kinematic analyses can give different results and it is not obvious which are most reliable. Using extensive sets of mock data of various sizes (mimicking 'ultra-faint' and 'classical' dSphs) and an MCMC engine, here we investigate biases, uncertainties, and limitations of analyses based on parametric solutions to the spherical Jeans equation. For a variety of functional forms for the tracer and DM density profiles, as well as the orbital anisotropy profile, we examine reliability of estimates for the astrophysical J- and D-factors for annihilation and decay, respectively. For large (N > 1000) stellar-kinematic samples typical of 'classical' dSphs, errors tend to be dominated by systematics, which can be reduced through the use of sufficiently general and flexible functional forms. For small (N < 100) samples typical of 'ultrafaints', statistical uncertainties tend to dominate systematic errors and flexible models are less necessary. We define an optimal strategy that would mitigate sensitivity to priors and other aspects of analyses based on the spherical Jeans equation. We also find that the assumption of spherical symmetry can bias estimates of J (with the 95% credibility intervals not encompassing the true J-factor) when the object is mildly triaxial (axis ratios b/a = 0.8, c/a = 0.6). A concluding table summarises the typical error budget and biases for the different sample sizes considered.

21 pages, 20 figures. Minor changes (several clarifications): match the MNRAS accepted version

References in corpus (21)

• Dark Matter Candidates from Particle Physics and Methods of Detection
• Measuring the inclination and mass-to-light ratio of axisymmetric galaxies via anisotropic Jeans models of stellar kinematics
• A common mass scale for satellite galaxies of the Milky Way
• The spin and shape of dark matter haloes in the Millennium simulation of a LambdaCDM universe
• Precise constraints on the dark matter content of Milky Way dwarf galaxies for gamma-ray experiments
• The Most Dark Matter Dominated Galaxies: Predicted Gamma-ray Signals from the Faintest Milky Way Dwarfs
• The shapes, orientation, and alignment of Galactic dark matter subhalos
• Constraints on decaying Dark Matter from XMM-Newton observations of M31
• Bounds on Cross-sections and Lifetimes for Dark Matter Annihilation and Decay into Charged Leptons from Gamma-ray Observations of Dwarf Galaxies
• Cores and Cusps in the Dwarf Spheroidals
• Dynamical models with a general anisotropy profile
• Baryonic and dark matter distribution in cosmological simulations of spiral galaxies
• Indirect Dark Matter Detection Limits from the Ultra-Faint Milky Way Satellite Segue 1
• A Markov Chain Monte Carlo for Galactic Cosmic Ray physics: I. Method and results for the Leaky Box Model
• Dark matter in the classical dwarf spheroidal galaxies: a robust constraint on the astrophysical factor for gamma-ray flux calculations
• p, He, and C to Fe cosmic-ray primary fluxes in diffusion models: Source and transport signatures on fluxes and ratios
• gamma-rays from annihilating dark matter in galaxy clusters: stacking vs single source analysis
• Decaying dark matter: a stacking analysis of galaxy clusters to improve on current limits
• Dark Matter annihilation in Draco: new considerations of the expected gamma flux
• Could the Fermi-LAT detect gamma-rays from dark matter annihilation in the dwarf galaxies of the Local Group?
• Disentangling cosmic-ray and dark-matter induced gamma-rays in galaxy clusters?

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• Search for dark matter signals towards a selection of recently-detected DES dwarf galaxy satellites of the Milky Way with H.E.S.S
• Particle dark matter searches outside the Local Group
• Dwarf spheroidal J-factors without priors: A likelihood-based analysis for indirect dark matter searches
• Current and future gamma-ray searches for dark-matter annihilation beyond the unitarity limit
• Extragalactic Observatory Science with the ASTRI Mini-Array at the Observatorio del Teide
• Galactic Observatory Science with the ASTRI Mini-Array at the Observatorio del Teide
• Wobbly Dark Matter Signals at Cherenkov Telescopes from Long Lived Mediator Decays
• Dark matter indirect detection limits from complete annihilation patterns
• Dependence of accessible dark matter annihilation cross-sections on the density profiles of dwarf spheroidal galaxies with the Cherenkov Telescope Array
• AMS-02 antiprotons and dark matter: Trimmed hints and robust bounds
• The quest for dark matter in dwarf spheroidal galaxies with the Cherenkov Telescope Array