Searching for Dark Matter Annihilation from Milky Way Dwarf Spheroidal Galaxies with Six Years of Fermi Large Area Telescope Data

A simple and natural explanation for the dynamics and morphology of the Local Group Dwarf Spheroidal galaxies, Draco (Dra) and Ursa Minor (UMi), is that they are weakly unbound stellar systems with no significant dark matter component. A gentle, but persistent, Milky Way (MW) tide has left them in their current kinematic and morphological state (the “parametric tidal excitation”). A new test of a dark matter dominated dS potential follows from a careful observation of the “clumpiness” of the dS stellar surface density.

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Too big to fail in light of Gaia

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stz2511 ◽

2019 ◽

Vol 490 (1) ◽

pp. 231-242 ◽

Cited By ~ 12

Author(s):

Manoj Kaplinghat ◽

Mauro Valli ◽

Hai-Bo Yu

Keyword(s):

Dark Matter ◽

Milky Way ◽

Large Scatter ◽

Too Big To Fail ◽

Dwarf Spheroidal Galaxies ◽

Ursa Minor ◽

Spheroidal Galaxies

ABSTRACT We point out an anticorrelation between the central dark matter (DM) densities of the bright Milky Way dwarf spheroidal galaxies (dSphs) and their orbital pericenter distances inferred from Gaia data. The dSphs that have not come close to the Milky Way centre (like Fornax, Carina and Sextans) are less dense in DM than those that have come closer (like Draco and Ursa Minor). The same anticorrelation cannot be inferred for the ultrafaint dSphs due to large scatter, while a trend that dSphs with more extended stellar distributions tend to have lower DM densities emerges with ultrafaints. We discuss how these inferences constrain proposed solutions to the Milky Way’s too-big-to-fail problem and provide new clues to decipher the nature of DM.

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Relieving Tensions Related to the Dark Matter Interpretation of the Fermi-LAT Data

Galaxies ◽

10.3390/galaxies6030092 ◽

2018 ◽

Vol 6 (3) ◽

pp. 92

Author(s):

Man Chan

Keyword(s):

Dark Matter ◽

Synchrotron Radiation ◽

Milky Way ◽

Gamma Ray ◽

Feedback Process ◽

Dark Matter Annihilation ◽

Dwarf Spheroidal Galaxies ◽

Matter Model ◽

Consistent Picture ◽

Dark Matter Model

Recently, many studies indicate that the GeV gamma ray excess signal from the central Milky Way can be best explained by ∼40–50 GeV dark matter annihilating via the b b ¯ channel. However, this model appears to be disfavored by the recent Fermi-LAT data for dwarf spheroidal galaxies and the constraint from synchrotron radiation. In this article, we describe a consistent picture to relieve the tensions between the dark matter annihilation model and the observations. We show that a baryonic feedback process is the key to alleviate the tensions and the ∼40–50 GeV dark matter model is still the best one to account for the GeV gamma ray excess in the Milky Way.

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Dark matter annihilation and decay in dwarf spheroidal galaxies: the classical and ultrafaint dSphs

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stv1601 ◽

2015 ◽

Vol 453 (1) ◽

pp. 849-867 ◽

Cited By ~ 92

Author(s):

V. Bonnivard ◽

C. Combet ◽

M. Daniel ◽

S. Funk ◽

A. Geringer-Sameth ◽

...

Keyword(s):

Dark Matter ◽

Dark Matter Annihilation ◽

Dwarf Spheroidal Galaxies ◽

Spheroidal Galaxies

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Fermi–LAT Observations toward the Galactic Center

Proceedings of the International Astronomical Union ◽

10.1017/s1743921316012254 ◽

2016 ◽

Vol 11 (S322) ◽

pp. 11-20

Author(s):

Simona Murgia

Keyword(s):

Dark Matter ◽

Milky Way ◽

Galactic Center ◽

Point Sources ◽

Source Detection ◽

Large Area ◽

Dark Matter Annihilation ◽

Γ Rays ◽

Inner Region

AbstractThe inner region of the Milky Way is one of the most interesting and complex regions of the γ-ray sky. Intense interstellar emission and point sources contribute to it, as well as other potential components such as an unresolved population of point sources and dark matter. In recent years, claims have been made of an excess consistent with a dark matter annihilation signal in the data collected with the Fermi Large Area Telescope (Fermi–LAT). Although these results are intriguing, the complexity involved in modeling the foreground and background emission from conventional astrophysical sources of γ-rays makes a conclusive interpretation of these results challenging. In these proceedings, I discuss Fermi–LAT observations of the Galactic center region, the methodology for point source detection and treatment of the interstellar emission, the characterization of the GeV excess, and implications for dark matter.

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