The Most Dark-Matter-dominated Galaxies: Predicted Gamma-Ray Signals from the Faintest Milky Way Dwarfs

By L. Strigari, S. Koushiappas, James S. Bullock, M. Kaplinghat, J. Simon, M. Geha, B. Willman. 2007

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We use kinematic data from three new nearby, extremely low luminosity Milky Way dwarf galaxies (Ursa Major II, Willman 1, and Coma Berenices) to constrain the properties of their dark matter halos, and from these we make predictions for the γ-ray flux from annihilation of dark matter particles in these halos. We show that these ~103 L☉ dwarfs are the most dark-matter-dominated galaxies known, with total masses within 100 pc that are in excess of 106 M☉. Coupled with their relative proximity, their large masses imply that they should have mean γ-ray fluxes that are comparable to or greater than those of any other known satellite galaxy of the Milky Way. Our results are robust to both variations of the inner slope of the density profile and the effect of tidal interactions. The fluxes could be boosted by up to 2 orders of magnitude if we include the density enhancements caused by surviving dark matter substructure.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/31ef551fdee7075fd659a94d041c4d34617011ed

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Citations in the corpus

A COMPLETE SPECTROSCOPIC SURVEY OF THE MILKY WAY SATELLITE SEGUE 1: THE DARKEST GALAXY (2010, methodology): “These objects promise clues to the extreme limits of galaxy formation (Gilmore et al. 2007; Strigari et al. 2008a) and perhaps to the formation of the first galaxies in the early universe (e.g., Bovill & Ricotti 2009), as well as offering insights into dark matter physics.”
Teraelectronvolt Astronomy (2010, background): “Favorable objects include the Galactic center, dwarf spheriodal galaxies such as Draco, Ursa Minor and Ursa Major, or Willman 1 (Strigari et al. 2008) as well as microhalos and DM enhancements predicted around intermediate-mass black holes (IMBHs) in the Galactic vicinity (Bertone, Zentner & Silk…”
A lower bound on the mass of dark matter particles (2008, background): “3) with those, based on [104–106], where DM density profiles were obtained under the assumptions of different anisotropic distributions of stars in dSphs.”
SEARCH FOR GAMMA-RAY EMISSION FROM DES DWARF SPHEROIDAL GALAXY CANDIDATES WITH FERMI-LAT DATA (2015, background): “Additionally, SDSS data led to the discovery of a new population of “ultra-faint” satellite galaxies, which were found to be the most DM dominated objects known (Simon & Geha 2007; Strigari et al. 2008b; Geha et al. 2009).”
Farthest Neighbor: The Distant Milky Way Satellite Eridanus II (2016, background): “(e.g., Strigari et al. 2008; Essig et al. 2009; Charbonnier et al. 2011; Martinez 2015; Geringer-Sameth et al. 2015).”
Dark matter and fundamental physics with the Cherenkov Telescope Array (2012, unknown): “While the former is motivated by numericalN−body simulations, the latter seems to be more consistent with observations [78], but the issue is still under debate [see, e.g., 79] The standard cusped profile is the Navarro, Frenk & White form (NFW) [80], while more recently it has been shown that the E”
Hundreds of Milky Way Satellites? Luminosity Bias in the Satellite Luminosity Function (2008, background): “For example,Willman 1 was originally of unclear classification (Willman et al. 2005), but is now generally recognized as being a darkmatterYdominated dSph (Martin et al. 2007; Strigari et al. 2008b).”
THE LEAST-LUMINOUS GALAXY: SPECTROSCOPY OF THE MILKY WAY SATELLITE SEGUE 1 (2008, methodology): “We test this by adding a sinusoidal term to the systemic velocity, varying the amplitude and scale radius (Strigari et al. 2008a).”
Galactic Searches for Dark Matter (2012, methodology): “Phrased in this context, Strigari et al. (2008) highlighted how there exists a common mass scale for all of the Milky Way satellites of 106 M within 100 pc, and 107 M within 300 pc (Figure 6).”
Dark matter annihilation and decay in dwarf spheroidal galaxies: the classical and ultrafaint dSphs (2015, methodology): “The likelihood function reads (Strigari et al. 2008): Lunbin = Nstars∏ i=1 (2π)−1/2√ σ2p (Ri)+∆2vi exp [ −1 2 ( (vi−v̄)2 σ2p (Ri)+∆2vi )] , (10) where the dispersion of velocities at radiusRi of the i-th star comes from both the intrinsic dispersion σp(Ri) from equation (3) and the measurement…”