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arXiv · 1805.02588

A Gaia DR2 search for dwarf galaxies towards Fermi-LAT sources: implications for annihilating dark matter

Ioana Ciucă·Daisuke Kawata·Shin'ichiro Ando·Francesca Calore·Justin I. Read·Cecilia Mateu
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Abstract

We make a first attempt to find dwarf galaxies in eight \Fermi-LAT extended, unassociated, source fields using \Gaia\ DR2. We probe previously unexplored heliocentric distances of $d<20$~kpc with an extreme-deconvolution (XD) technique. We find no signature of a dwarf galaxy in any of these fields despite \Gaia's excellent astrometric accuracy. We estimate our detection limits by applying the XD method to mock data, obtaining a conservative limit on the stellar mass of $M_* < 10^4$~M$_{\sun}$ for $d < 20$\, kpc. Such a low stellar mass implies either a low-mass subhalo, or a massive stripped-down subhalo. We use an analytic model for stripped subhalos to argue that, given the sizes and fluxes of the \Fermi-LAT sources, we can reject the hypothesis that they owe to dark matter annihilation.

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Ioana Ciucă, Daisuke Kawata, Shin'ichiro Ando, Francesca Calore, Justin I. Read, Cecilia Mateu. 2018-05-07. A Gaia DR2 search for dwarf galaxies towards Fermi-LAT sources: implications for annihilating dark matter. https://doi.org/10.1093/mnras%2Fsty1994

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