1. |
- Ackermann, M., et al.
(författare)
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Fermi LAT search for dark matter in gamma-ray lines and the inclusive photon spectrum
- 2012
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Ingår i: Physical Review D. - 1550-7998 .- 1550-2368. ; 86:2
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Tidskriftsartikel (refereegranskat)abstract
- Dark matter particle annihilation or decay can produce monochromatic gamma-ray lines and contribute to the diffuse gamma-ray background. Flux upper limits are presented for gamma-ray spectral lines from 7 to 200 GeV and for the diffuse gamma-ray background from 4.8 GeV to 264 GeV obtained from two years of Fermi Large Area Telescope data integrated over most of the sky. We give cross-section upper limits and decay lifetime lower limits for dark matter models that produce gamma-ray lines or contribute to the diffuse spectrum, including models proposed as explanations of the PAMELA and Fermi cosmic-ray data.
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2. |
- Abdo, A. A., et al.
(författare)
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Fermi Large Area Telescope Search for Photon Lines from 30 to 200 GeV and Dark Matter Implications
- 2010
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 104:9, s. 091302-
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Tidskriftsartikel (refereegranskat)abstract
- Dark matter (DM) particle annihilation or decay can produce monochromatic gamma rays readily distinguishable from astrophysical sources. gamma- ray line limits from 30 to 200 GeV obtained from 11 months of Fermi Large Area Space Telescope data from 20-300 GeV are presented using a selection based on requirements for a gamma-ray line analysis, and integrated over most of the sky. We obtain gamma-ray line flux upper limits in the range 0.6-4.5 x 10(-9) cm(-2) s(-1), and give corresponding DM annihilation cross-section and decay lifetime limits. Theoretical implications are briefly discussed.
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3. |
- Ackermann, M., et al.
(författare)
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Search for gamma-ray spectral lines with the Fermi Large Area Telescope and dark matter implications
- 2013
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Ingår i: Physical Review D. - 1550-7998 .- 1550-2368. ; 88:8, s. 082002-
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Tidskriftsartikel (refereegranskat)abstract
- Weakly interacting massive particles (WIMPs) are a theoretical class of particles that are excellent dark matter candidates. WIMP annihilation or decay may produce essentially monochromatic gamma rays detectable by the Fermi Large Area Telescope (LAT) against the astrophysical gamma-ray emission of the Galaxy. We have searched for spectral lines in the energy range 5-300 GeV using 3.7 years of data, reprocessed with updated instrument calibrations and an improved energy dispersion model compared to the previous Fermi-LAT Collaboration line searches. We searched in five regions selected to optimize sensitivity to different theoretically motivated dark matter density distributions. We did not find any globally significant lines in our a priori search regions and present 95% confidence limits for annihilation cross sections of self-conjugate WIMPs and decay lifetimes. Our most significant fit occurred at 133 GeV in our smallest search region and had a local significance of 3.3 standard deviations, which translates to a global significance of 1.5 standard deviations. We discuss potential systematic effects in this search, and examine the feature at 133 GeV in detail. We find that the use both of reprocessed data and of additional
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4. |
- Ackermann, M., et al.
(författare)
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Dark matter constraints from observations of 25 Milky Way satellite galaxies with the Fermi Large Area Telescope
- 2014
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Ingår i: Physical Review D. - 1550-7998 .- 1550-2368. ; 89:4
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Tidskriftsartikel (refereegranskat)abstract
- The dwarf spheroidal satellite galaxies of the Milky Way are some of the most dark-matter-dominated objects known. Due to their proximity, high dark matter content, and lack of astrophysical backgrounds, dwarf spheroidal galaxies are widely considered to be among the most promising targets for the indirect detection of dark matter via gamma rays. Here we report on.-ray observations of 25 Milky Way dwarf spheroidal satellite galaxies based on 4 years of Fermi Large Area Telescope (LAT) data. None of the dwarf galaxies are significantly detected in. rays, and we present.-ray flux upper limits between 500 MeV and 500 GeV. We determine the dark matter content of 18 dwarf spheroidal galaxies from stellar kinematic data and combine LAT observations of 15 dwarf galaxies to constrain the dark matter annihilation cross section. We set some of the tightest constraints to date on the annihilation of dark matter particles with masses between 2 GeV and 10 TeV into prototypical standard model channels. We find these results to be robust against systematic uncertainties in the LAT instrument performance, diffuse.-ray background modeling, and assumed dark matter density profile.
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5. |
- Ackermann, M., et al.
(författare)
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SEARCH FOR DARK MATTER SATELLITES USING FERMI-LAT
- 2012
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Ingår i: Astrophysical Journal. - 0004-637X .- 1538-4357. ; 747:2, s. 121-
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Tidskriftsartikel (refereegranskat)abstract
- Numerical simulations based on the ACDM model of cosmology predict a large number of as yet unobserved Galactic dark matter satellites. We report the results of a Large Area Telescope (LAT) search for these satellites via the gamma-ray emission expected from the annihilation of weakly interacting massive particle (WIMP) dark matter. Some dark matter satellites are expected to have hard gamma-ray spectra, finite angular extents, and a lack of counterparts at other wavelengths. We sought to identify LAT sources with these characteristics, focusing on gamma-ray spectra consistent with WIMP annihilation through the b (b) over bar channel. We found no viable dark matter satellite candidates using one year of data, and we present a framework for interpreting this result in the context of numerical simulations to constrain the velocity-averaged annihilation cross section for a conventional 100 GeV WIMP annihilating through the b (b) over bar channel.
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6. |
- Ackermann, M., et al.
(författare)
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Searching for Dark Matter Annihilation from Milky Way Dwarf Spheroidal Galaxies with Six Years of Fermi Large Area Telescope Data
- 2015
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Ingår i: Physical Review Letters. - : American Physical Society. - 0031-9007 .- 1079-7114. ; 115:23
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Tidskriftsartikel (refereegranskat)abstract
- The dwarf spheroidal satellite galaxies (dSphs) of the Milky Way are some of the most dark matter (DM) dominated objects known. We report on gamma-ray observations of Milky Way dSphs based on six years of Fermi Large Area Telescope data processed with the new PASS8 event-level analysis. None of the dSphs are significantly detected in gamma rays, and we present upper limits on the DM annihilation cross section from a combined analysis of 15 dSphs. These constraints are among the strongest and most robust to date and lie below the canonical thermal relic cross section for DM of mass less than or similar to 100 GeV annihilating via quark and tau-lepton channels.
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7. |
- Drlica-Wagner, A., et al.
(författare)
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SEARCH FOR GAMMA-RAY EMISSION FROM DES DWARF SPHEROIDAL GALAXY CANDIDATES WITH FERMI-LAT DATA
- 2015
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Ingår i: Astrophysical Journal Letters. - 2041-8205 .- 2041-8213. ; 809:1
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Tidskriftsartikel (refereegranskat)abstract
- Due to their proximity, high dark-matter (DM) content, and apparent absence of non-thermal processes, Milky Way dwarf spheroidal satellite galaxies (dSphs) are excellent targets for the indirect detection of DM. Recently, eight new dSph candidates were discovered using the first year of data from the Dark Energy Survey (DES). We searched for gamma-ray emission coincident with the positions of these new objects in six years of Fermi Large Area Telescope data. We found no significant excesses of gamma-ray emission. Under the assumption that the DES candidates are dSphs with DM halo properties similar to the known dSphs, we computed individual and combined limits on the velocity-averaged DM annihilation cross section for these new targets. If the estimated DM content of these dSph candidates is confirmed, they will constrain the annihilation cross section to lie below the thermal relic cross section for DM particles with masses less than or similar to 20 GeV annihilating via the b (b) over bar or pi(+)pi(-) channels.
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8. |
- Amelino-Camelia, G., et al.
(författare)
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Physics with the KLOE-2 experiment at the upgraded DA Phi NE
- 2010
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Ingår i: European Physical Journal C. - : Springer Science and Business Media LLC. - 1434-6044 .- 1434-6052. ; 68:3-4, s. 619-681
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Forskningsöversikt (refereegranskat)abstract
- Investigation at a f-factory can shed light on several debated issues in particle physics. We discuss: (i) recent theoretical development and experimental progress in kaon physics relevant for the Standard Model tests in the flavor sector, (ii) the sensitivity we can reach in probing CPT and Quantum Mechanics from time evolution of entangled-kaon states, (iii) the interest for improving on the present measurements of non-leptonic and radiative decays of kaons and eta/eta' mesons, (iv) the contribution to understand the nature of light scalar mesons, and (v) the opportunity to search for narrow di-lepton resonances suggested by recent models proposing a hidden dark-matter sector. We also report on the e(+)e(-) physics in the continuum with the measurements of (multi) hadronic cross sections and the study of gamma gamma processes.
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9. |
- Ávalos, N., et al.
(författare)
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Skipper CCDs for the search of a daily modulation of Dark Matter signal in the DMSQUARE experiment
- 2022
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Ingår i: 17th International Conference on Topics in Astroparticle and Underground Physics (TAUP 2021), 26 August-3 September 2021, Valencia. - Bristol : Institute of Physics Publishing (IOPP).
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Konferensbidrag (refereegranskat)abstract
- The Dark Matter Daily Modulation experiment (DMSQUARE) seeks for dark matter interactions with a Skipper CCD. It is currently running at surface level in Bariloche, Argentina, and will be moved to a shallow underground site at Sierra Grande, Argentina in November 2021. The low threshold achieved by Skipper CCDs allows to search for electron recoil events with an ionization energy down to 1.2 eV. In order to extract a potential dark matter signal from noise at the single electron level, we propose to search for a diurnal modulation of events, resulting from the potential interaction of the dark matter wind with the particles in the Earth. Depending on the model, mass and cross-section, this modulation can be maximum at 40deg of latitude in the Southern Hemisphere, where DMSQUARE is operated. In this article we present the experiment, report preliminary results with a prototype Skipper CCD taking data at surface level and comment on future prospects.
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