Comprehensive search for dark matter annihilation in dwarf galaxies

By A. Geringer-Sameth, S. Koushiappas, M. Walker. 2014

138 citations recorded by the source corpus.

We present a new formalism designed to discover dark matter annihilation occurring in the Milky Way's dwarf galaxies. The statistical framework extracts all available information in the data by simultaneously combining observations of all the dwarf galaxies and incorporating the impact of particle physics properties, the distribution of dark matter in the dwarfs, and the detector response. The method performs maximally powerful frequentist searches and produces confidence limits on particle physics parameters. Probability distributions of test statistics under various hypotheses are constructed exactly, without relying on large sample approximations. The derived limits have proper coverage by construction and claims of detection are not biased by imperfect background modeling. We implement this formalism using data from the Fermi Gamma-ray Space Telescope to search for an annihilation signal in the complete sample of Milky Way dwarfs whose dark matter distributions can be reliably determined. We find that the observed data is consistent with background for each of the dwarf galaxies individually as well as in a joint analysis. The strongest constraints are at small dark matter particle masses. Taking the median of the systematic uncertainty in dwarf density profiles, the cross section upper limits are below the pure s-wave weak scale relic abundance value (2.2 x 10^-26 cm^3/s) for dark matter masses below 26 GeV (for annihilation into b quarks), 29 GeV (tau leptons), 35 GeV (up, down, strange, and charm quarks and gluons), 6 GeV (electrons/positrons), and 114 GeV (two-photon final state). For dark matter particle masses less than 1 TeV, these represent the strongest limits obtained to date using dwarf galaxies.

Subfields: Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/ed76b565cedcaf79acaadb4e2a0ab89616c1333d

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In Nuclear and High Energy Physics

1. M. Walker
2. L. Strigari
3. Justin I. Read
4. V. Belokurov
5. A. Peter
6. T. Eifler
7. E. Krause
8. Risa Wechsler

Citations in the corpus

• SEARCH FOR GAMMA-RAY EMISSION FROM DES DWARF SPHEROIDAL GALAXY CANDIDATES WITH FERMI-LAT DATA (2015, methodology): “We obtain a similar best-fit value, Jlog 18.1 0.110( ) = at d 100 kpc= , using the J-factors derived by Geringer-Sameth et al. (2015a), who assumed a generalized NFW profile and omitted Willman 1.75 We note that the limited scatter in Figure 3 is primarily due to the known dSphs residing in…”
• The hidden giant: discovery of an enormous Galactic dwarf satellite in Gaia DR2 (2018, background): “…to the expected signal to noise in quadrature as SNR2 =∑ s2/b, where the sum runs over energy and spatial bins, and s and b are the expected number of dark matter photons and background events detected in each (generally infinitesimal) bin (see equation 18 of Geringer-Sameth et al. 2015a).”
• EIGHT ULTRA-FAINT GALAXY CANDIDATES DISCOVERED IN YEAR TWO OF THE DARK ENERGY SURVEY (2015, background): “…cold dark matter paradigm (e.g., Bullock et al. 2001), and has motivated studies ranging from the physical conditions at the time of reionization (e.g., Bullock et al. 2000; Benson et al. 2002), to the particle properties of dark matter (e.g., Ackermann et al. 2015; Geringer-Sameth et al. 2015a).”
• Cosmological Moduli and the Post-Inflationary Universe: A Critical Review (2015, methodology): “A joint analysis of seven Milky Way dwarf galaxies using a frequentist Neyman construction and Pass 7 data from the Fermi Gamma-ray Space Telescope undertaken in [58, 59] excludes generic thermal WIMP candidates with mass less than ∼ 40 GeV annihilating to bb̄ final states13.”
• Milky Way Satellite Census. I. The Observational Selection Function for Milky Way Satellites in DES Y3 and Pan-STARRS DR1 (2019, background): “…& Peek 2018; Graus et al. 2019; Katz et al. 2019), and the nature of dark matter (e.g., Bergström et al. 1998; Spekkens et al. 2013; Malyshev et al. 2014; Ackermann et al. 2015; Geringer-Sameth et al. 2015; Bullock & Boylan-Kolchin 2017; Clesse & Garćıa-Bellido 2018; Nadler et al. 2019a).”
• Gravitational probes of dark matter physics (2017, background): “Indirect detection searches for dark matter annihilation or decay in the Universe today can improve signal over background by targeting high-density regions — be it the Galactic Center [441, 442, 443, 444, 445, 446, 447, 448, 449, 450, 451, 452, 453, 454, 455, 456], satellite galaxies [457, 458, 459”
• SEARCHING FOR DARK MATTER ANNIHILATION IN RECENTLY DISCOVERED MILKY WAY SATELLITES WITH FERMI-LAT (2016, methodology): “…on DM annihilation that are competitive with other DM targets such as the Galactic center (e.g., Abdo et al. 2010; Ackermann et al. 2011; Geringer-Sameth & Koushiappas 2011; Mazziotta et al. 2012; Ackermann et al. 2014; Geringer-Sameth et al. 2015b,c; Hooper & Linden 2015; Li et al. 2016).”
• Dark matter annihilation and decay in dwarf spheroidal galaxies: the classical and ultrafaint dSphs (2015, background): “…the DES survey (DES Collaboration et al. 2015; Koposov et al. 2015) and already searched for in Fermi-LAT data (Fermi-LAT Collaboration et al. 2015; Geringer-Sameth et al. 2015) call for a continued effort on c© Xxxx RAS, MNRAS 000, 1–18 this topic (see also Laevens et al. 2015; Martin et al.…”