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Title: Searching for Dark Matter annihilation in recently discovered Milky Way satellites with FERMI-LAT

Here, we search for excess γ-ray emission coincident with the positions of confirmed and candidate Milky Way satellite galaxies using six years of data from the Fermi Large Area Telescope (LAT). Our sample of 45 stellar systems includes 28 kinematically confirmed dark-matter-dominated dwarf spheroidal galaxies (dSphs) and 17 recently discovered systems that have photometric characteristics consistent with the population of known dSphs. For each of these targets, the relative predicted γ-ray flux due to dark matter annihilation is taken from kinematic analysis if available, and estimated from a distance-based scaling relation otherwise, assuming that the stellar systems are DM-dominated dSphs. LAT data coincident with four of the newly discovered targets show a slight preference (each $$\sim $$2σ local) for γ-ray emission in excess of the background. However, the ensemble of derived γ-ray flux upper limits for individual targets is consistent with the expectation from analyzing random blank-sky regions, and a combined analysis of the population of stellar systems yields no globally significant excess (global significance $$\lt 1\sigma $$). Our analysis has increased sensitivity compared to the analysis of 15 confirmed dSphs by Ackermann et al. The observed constraints on the DM annihilation cross section are statistically consistent with the background expectation, improving by a factor of ~2 for large DM masses ($${m}_{\mathrm{DM},b\bar{b}}\gtrsim 1\,\mathrm{TeV}$$ and $${m}_{\mathrm{DM},{\tau }^{+}{\tau }^{-}}\gtrsim 70\,\mathrm{GeV}$$) and weakening by a factor of ~1.5 at lower masses relative to previously observed limits.
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Publication Date:
Report Number(s):
FERMILAB-PUB-16-073-AE; arXiv:1611.03184
Journal ID: ISSN 1538-4357; 1496953
Grant/Contract Number:
AC02-07CH11359; AC02-76SF00515
Type:
Accepted Manuscript
Journal Name:
The Astrophysical Journal (Online)
Additional Journal Information:
Journal Name: The Astrophysical Journal (Online); Journal Volume: 834; Journal Issue: 2; Journal ID: ISSN 1538-4357
Publisher:
Institute of Physics (IOP)
Research Org:
Argonne National Lab. (ANL), Argonne, IL (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Los Alamos National Lab. (LANL), Los Alamos, NM (United States); SLAC National Accelerator Lab., Menlo Park, CA (United States); Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)
Sponsoring Org:
USDOE Office of Science (SC), High Energy Physics (HEP) (SC-25)
Contributing Orgs:
The Fermi-LAT and DES Collaborations
Country of Publication:
United States
Language:
English
Subject:
79 ASTRONOMY AND ASTROPHYSICS; dwarf gamma rays galaxies; dark matter galaxies; dark matter; galaxies: dwarf; gamma rays: galaxies
OSTI Identifier:
1353474
Alternate Identifier(s):
OSTI ID: 1355744