Browsing by Author "Aguirre-Santaella, Alejandra"
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Item Spectral and spatial analysis of the dark matter subhalo candidates among Fermi Large Area Telescope unidentified sources(IOP, 2019-11-28) Coronado-Blázquez, Javier; Sánchez-Conde, Miguel A.; Mauro, Mattia Di; Aguirre-Santaella, Alejandra; Ciucă, Ioana; Domínguez, Alberto; Kawata, Daisuke; Mirabal, NéstorFermi-LAT unidentified sources (unIDs) have proven to be compelling targets for performing indirect dark matter (DM) searches. In a previous work, we found that among the 1235 unIDs in Fermi-LAT's catalogs (3FGL, 2FHL and 3FHL) only 44 of those are DM subhalos candidates. We now implement a spectral analysis to test whether these remaining sources are compatible or not with DM origin. This analysis is executed using almost 10 years of Pass 8 Fermi-LAT data. None of the unIDs are found to significantly prefer DM-induced emission compared to other, more conventional, astrophysical sources. In order to discriminate between pulsar and DM sources, we developed a new method which is based on the source's spectral curvature, peak energy, and its detection significance. We also look for spatial extension, which may be a hint for a DM origin according to our N-body simulation studies of the subhalo population. In addition, we used Gaia DR2 data to search for a potential stellar counterpart to our best DM subhalo candidates and, although no firm associations could be found, one of them coincides with the Sagittarius stream. Finally, previous constraints on the DM annihilation cross section are updated with the new number of remaining DM subhalo candidates among unIDs. Our limits now rule out canonical thermal WIMPs up to masses of 10 GeV for bbar b and 20 GeV for τ+τ− annihilation channels, in this way being as sensitive and complementary to those obtained from other targets and probes.Item Unidentified Gamma-ray Sources as Targets for Indirect Dark Matter Detection with the Fermi-Large Area Telescope(2019-06) Coronado-Blázquez, Javier; Sánchez-Conde, Miguel A.; Domínguez, Alberto; Aguirre-Santaella, Alejandra; Di Mauro, Mattia; Mirabald, Néstor; Nieto, Daniel; Charles, EricOne of the predictions of the ΛCDM cosmological framework is the hierarchical formation of structure, giving rise to dark matter (DM) halos and subhalos. When the latter are massive enough they retain gas (i.e., baryons) and become visible. This is the case of the dwarf satellite galaxies in the Milky Way (MW). Below a certain mass, halos may not accumulate significant amounts of baryons and remain completely dark. However, if DM particles are Weakly Interacting Massive Particles (WIMPs), we expect them to annihilate in subhalos, producing gamma rays which can be detected with the Fermi satellite. Using the three most recent point-source Fermi Large Area Telescope (LAT) catalogs (3FGL, 2FHL and 3FHL), we search for DM subhalo candidates among the unidentified sources, i.e., sources with no firm association to a known astrophysical object. We apply several selection criteria based on the expected properties of the DM-induced emission from subhalos, which allow us to significantly reduce the list of potential candidates. Then, by characterizing the minimum detection flux of the instrument and comparing our sample to predictions from the Via Lactea II (VL-II) N-body cosmological simulation, we place conservative and robust constraints on the hσvi − mDM parameter space. For annihilation via the τ+τ− channel, we put an upper limit of 4 × 10−26 (5 × 10−25) cm3 s−1 for a mass of 10 (100) GeV. A critical improvement over previous treatments is the repopulation we made to include low-mass subhalos below the VL-II mass resolution. With more advanced subhalo candidate filtering the sensitivity reach of our method can potentially improve these constraints by a factor 3 (2) for τ+τ− (b¯b) channel.