The Observed Properties of Dark Matter on Small Spatial Scales

Gilmore, G.; Wilkinson, M. I.; Wyse, Rosemary F. Ġ.; Kleyna, Jan; Koch, Andreas; Evans, N. W.; Grebel, Eva K.

doi:10.1086/518025

Cited by 492 publications

(703 citation statements)

References 97 publications

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“…According to various previous papers (e.g., Gilmore et al 2007;Strigari et al 2010;Hayashi & Chiba 2012), the dark matter density profile in dSphs, especially the inner slope, is not necessarily the cusped profiles predicted by ΛCDM based N -body simulations. Therefore, we do not confine ourselves to cosmological motivated profiles such as the Navarro-Frenk-White (NFW) (Navarro et al 1996(Navarro et al , 1997 or Einasto profiles (e.g., Navarro et al 2010).…”

Section: Dark Matter Halo Modelmentioning

confidence: 84%

Dark matter annihilation and decay from non-spherical dark halos in galactic dwarf satellites

Hayashi

Ichikawa

Matsumoto

et al. 2016

Mon. Not. R. Astron. Soc.

111

119

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The dwarf spheroidal galaxies (dSphs) in the Milky Way are the primary targets in the indirect searches for particle dark matter. To set robust constraints on candidate of dark matter particles, understanding the dark halo structure of these systems is of substantial importance. In this paper, we first evaluate the astrophysical factors for dark matter annihilation and decay for 24 dSphs, with taking into account a non-spherical dark halo, using generalized axisymmetric mass models based on axisymmetric Jeans equations. First, from a fitting analysis of the most recent kinematic data available, our axisymmetric mass models are a much better fit than previous spherical ones, thus, our work should be the most realistic and reliable estimator for astrophysical factors. Secondly, we find that among analysed dSphs, the ultra-faint dwarf galaxies Triangulum II and Ursa Major II are the most promising but large uncertain targets for dark matter annihilation while the classical dSph Draco is the most robust and detectable target for dark matter decay. It is also found that the non-sphericity of luminous and dark components influences the estimate of astrophysical factors, even though these factors largely depend on the sample size, the prior range of parameters and the spatial extent of the dark halo. Moreover, owing to these effects, the constraints on the dark matter annihilation cross-section are more conservative than those of previous spherical works. These results are important for optimizing and designing dark matter searches in current and future multi-messenger observations by space and ground-based telescopes.

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Section: Dark Matter Halo Modelmentioning

confidence: 84%

Dark matter annihilation and decay from non-spherical dark halos in galactic dwarf satellites

Hayashi

Ichikawa

Matsumoto

et al. 2016

Mon. Not. R. Astron. Soc.

111

119

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“…So far, detailed studies of the mass and luminosity properties of substructures have been limited to the Milky Way 12,[24][25][26] , and to some extent also to M31 (ref. 27) at a distance of ∼1 Mpc from the Milky Way.…”

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confidence: 99%

Gravitational detection of a low-mass dark satellite galaxy at cosmological distance

Vegetti

Lagattuta

McKean

et al. 2012

Nature

363

392

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The mass-function of dwarf satellite galaxies that are observed around Local Group galaxies substantially differs from simulations 1-5 based on cold dark matter: the simulations predict many more dwarf galaxies than are seen. The Local Group, however, may be anomalous in this regard 6, 7 . A massive dark satellite in an early-type lens galaxy at z = 0.222 was recently found 8 using a new method based on gravitational lensing 9, 10 , suggesting that the mass fraction contained in substructure could be higher than is predicted from simulations. The lack of very low mass detections, however, prohibited any constraint on their mass function. Here we report the presence of a 1.9 ± 0.1 × 10 8 M ⊙ dark satellite in the Einstein-ring system JVAS B1938+666 (ref. 11) at z = 0.881, where M ⊙ denotes solar mass. This satellite galaxy has a mass similar to the Sagittarius 12 galaxy, which is a satellite of the Milky Way. We determine the logarithmic slope of the mass function for substructure beyond the local Universe to be α = 1.1 +0.6 −0.4 , with an average mass-fraction of f = 3.3 +3.6 −1.8 %, by combining data on both of these recently discovered galaxies. Our results are consistent with the predictions from cold dark matter simulations 13-15 at the 95 per cent confidence level,and therefore agree with the view that galaxies formed hierarchically in a Universe composed of cold dark matter.The gravitational lens system JVAS B1938+666 (ref. 11) has a bright infrared background galaxy at redshift 2.059 (ref. 16), which is gravitationally lensed into an almost complete Einstein ring of diameter ∼ 0.9 arcseconds by a massive elliptical galaxy at redshift 0. 881 (ref. 17). The bright, highly-magnified Einstein ring made this system an excellent candidate in which to to search for surface brightness anomalies caused by very low mass (dark matter) substructure in the halo around the high redshift elliptical lens galaxy. The presence of a low-mass substructure (e.g. a luminous or dark satellite galaxy; also denoted as substructure hereafter) in the lens galaxy 1

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“…In all dSphs that we have analyzed to date -Ursa Minor, Draco, Sextans, Carina, Leo I, Leo II -we find flat velocity dispersion profiles out to the outermost radii of our targets (Wilkinson et al 2004;Koch et al 2007bKoch et al , 2007cGilmore et al 2007). Only then a fall-off is seen.…”

Section: Radial Velocity Measurements Across the Full Angular Extent mentioning

confidence: 59%

“…The resulting mass-to-light ratios range from > 10 to < 300 km s −1 (e.g., Wilkinson et al 2006;Koch et al 2007c). The average dark matter density within two half-light radii is 0.1 M pc −3 for cored profiles under the above assumptions, while cusped models result in a maximum mass density of 60 M pc −3 within the inner 10 pc (Gilmore et al 2007). …”

Section: Cores Versus Cuspsmentioning

confidence: 99%

Baryonic Properties of the Darkest Galaxies

Grebel¹

2007

Proc. IAU

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Abstract. The faintest and darkest galaxies that we know of today are the dwarf spheroidal (dSph) galaxies. They appear to be plausible counterparts of cosmologically predicted small subhalos though their numbers do not (yet?) suffice to resolve the substructure crisis. Their mass-to-light ratios may go up to 1000 for the faintest objects, and their total masses are of the order of a few 10 6 to 10 7 M . Though most dSphs are dominated by old populations, they all show extended and presumably slow star formation histories with considerable enrichment. While environment has certainly affected their evolution, as evidenced by the morphology-gasdistance relations, intrinsic properties such as their (initial) baryon content may also have played a major role. The complexity and diversity of their star formation histories is surprising, and there are no obvious evolutionary connections to dwarf irregulars.

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The Observed Properties of Dark Matter on Small Spatial Scales

Cited by 492 publications

References 97 publications

Dark matter annihilation and decay from non-spherical dark halos in galactic dwarf satellites

Dark matter annihilation and decay from non-spherical dark halos in galactic dwarf satellites

Gravitational detection of a low-mass dark satellite galaxy at cosmological distance

Baryonic Properties of the Darkest Galaxies

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