Search for gamma-ray spectral lines with the Fermi Large Area Telescope and dark matter implications
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 γ rays detectable by the Fermi Large Area Telescope (LAT) against the astrophysical γ-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 information in the energy dispersion model contributes to the reduction in significance of the linelike feature near 130 GeV relative to significances reported in other works. We also find that the feature is narrower than the LAT energy resolution at the level of 2 to 3 standard deviations, which somewhat disfavors the interpretation of the 133 GeV feature as a real WIMP signal.
Additional Information
© 2013 American Physical Society. Received 23 May 2013; published 22 October 2013. The Fermi-LAT Collaboration acknowledges generous ongoing support from a number of agencies and institutes that have supported both the development and the operation of the LAT as well as scientific data analysis. These include the National Aeronautics and Space Administration and the Department of Energy in the United States, the Commissariat à l'Energie Atomique and the Centre National de la Recherche Scientifique/Institut National de Physique Nucléaire et de Physique des Particules in France, the Agenzia Spaziale Italiana and the Istituto Nazionale di Fisica Nucleare in Italy, the Ministry of Education, Culture, Sports, Science and Technology (MEXT), High Energy Accelerator Research Organization (KEK), and Japan Aerospace Exploration Agency (JAXA) in Japan, and the K. A. Wallenberg Foundation, the Swedish Research Council, and the Swedish National Space Board in Sweden. Additional support for science analysis during the operations phase is gratefully acknowledged from the Istituto Nazionale di Astrofisica in Italy and the Centre National d'É'tudes Spatiales in France. We would also like to thank Christoph Weniger for providing the limit values used in Fig. 10. J. Conrad is a Royal Swedish Academy of Sciences Research Fellow, funded by a grant from the K. A. Wallenberg Foundation. A. B. Hill was funded by a Marie Curie IOF, FP7/2007-2013 under Grant No. 275861. E. Troja is a NASA Postdoctoral Program Fellow.Attached Files
Published - PhysRevD.88.082002.pdf
Submitted - 1305.5597v3.pdf
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Additional details
- Eprint ID
- 42732
- Resolver ID
- CaltechAUTHORS:20131126-084952866
- NASA
- Department of Energy (DOE)
- Commissariat à l'Energie Atomique (CEA)
- Agenzia Spaziale Italiana (ASI)
- Ministry of Education, Culture, Sports, Science and Technology (MEXT)
- High Energy Accelerator Research Organization (KEK)
- Japan Aerospace Exploration Agency (JAXA)
- Knut and Alice Wallenberg Foundation
- Swedish Research Council
- Swedish National Space Board (SNSB)
- Istituto Nazionale di Astrofisica (INAF)
- Centre National d'Études Spatiales (CNES)
- FP7/2007-2013
- Marie Curie Fellowship
- 275861
- NASA Postdoctoral Program
- Institut National de Physique Nucléaire et de Physique des Particules (IN2P3)
- Centre National de la Recherche Scientifique (CNRS)
- Istituto Nazionale di Fisica Nucleare (INFN)
- Created
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2013-11-26Created from EPrint's datestamp field
- Updated
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2021-11-10Created from EPrint's last_modified field