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Title: The Fermi Galactic Center GeV excess and implications for dark matter

Abstract

Here, the region around the Galactic Center (GC) is now well established to be brighter at energies of a few GeV than what is expected from conventional models of diffuse gamma-ray emission and catalogs of known gamma-ray sources. We study the GeV excess using 6.5 yr of data from the Fermi Large Area Telescope. We characterize the uncertainty of the GC excess spectrum and morphology due to uncertainties in cosmic-ray source distributions and propagation, uncertainties in the distribution of interstellar gas in the Milky Way, and uncertainties due to a potential contribution from the Fermi bubbles. We also evaluate uncertainties in the excess properties due to resolved point sources of gamma rays. The GC is of particular interest, as it would be expected to have the brightest signal from annihilation of weakly interacting massive dark matter (DM) particles. However, control regions along the Galactic plane, where a DM signal is not expected, show excesses of similar amplitude relative to the local background. Furthermore, based on the magnitude of the systematic uncertainties, we conservatively report upper limits for the annihilation cross-section as a function of particle mass and annihilation channel.

Authors:
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Publication Date:
Research Org.:
SLAC National Accelerator Lab., Menlo Park, CA (United States)
Sponsoring Org.:
USDOE
Contributing Org.:
The Fermi LAT Collaboration
OSTI Identifier:
1355726
Grant/Contract Number:
AC02-76SF00515
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
The Astrophysical Journal (Online)
Additional Journal Information:
Journal Name: The Astrophysical Journal (Online); Journal Volume: 840; Journal Issue: 1; Journal ID: ISSN 1538-4357
Publisher:
Institute of Physics (IOP)
Country of Publication:
United States
Language:
English
Subject:
79 ASTRONOMY AND ASTROPHYSICS; cosmic rays; Galaxy: bulge; Galaxy: center; Galaxy: halo; gamma rays: general; ISM: general

Citation Formats

Ackermann, M., Ajello, M., Albert, A., Atwood, W. B., Baldini, L., Ballet, J., Barbiellini, G., Bastieri, D., Bellazzini, R., Bissaldi, E., Blandford, R. D., Bloom, E. D., Bonino, R., Bottacini, E., Brandt, T. J., Bregeon, J., Bruel, P., Buehler, R., Burnett, T. H., Cameron, R. A., Caputo, R., Caragiulo, M., Caraveo, P. A., Cavazzuti, E., Cecchi, C., Charles, E., Chekhtman, A., Chiang, J., Chiappo, A., Chiaro, G., Ciprini, S., Conrad, J., Costanza, F., Cuoco, A., Cutini, S., D’Ammando, F., Palma, F. de, Desiante, R., Digel, S. W., Lalla, N. Di, Mauro, M. Di, Venere, L. Di, Drell, P. S., Favuzzi, C., Fegan, S. J., Ferrara, E. C., Focke, W. B., Franckowiak, A., Fukazawa, Y., Funk, S., Fusco, P., Gargano, F., Gasparrini, D., Giglietto, N., Giordano, F., Giroletti, M., Glanzman, T., Gomez-Vargas, G. A., Green, D., Grenier, I. A., Grove, J. E., Guillemot, L., Guiriec, S., Gustafsson, M., Harding, A. K., Hays, E., Hewitt, J. W., Horan, D., Jogler, T., Johnson, A. S., Kamae, T., Kocevski, D., Kuss, M., Mura, G. La, Larsson, S., Latronico, L., Li, J., Longo, F., Loparco, F., Lovellette, M. N., Lubrano, P., Magill, J. D., Maldera, S., Malyshev, D., Manfreda, A., Martin, P., Mazziotta, M. N., Michelson, P. F., Mirabal, N., Mitthumsiri, W., Mizuno, T., Moiseev, A. A., Monzani, M. E., Morselli, A., Negro, M., Nuss, E., Ohsugi, T., Orienti, M., Orlando, E., Ormes, J. F., Paneque, D., Perkins, J. S., Persic, M., Pesce-Rollins, M., Piron, F., Principe, G., Rainò, S., Rando, R., Razzano, M., Razzaque, S., Reimer, A., Reimer, O., Sánchez-Conde, M., Sgrò, C., Simone, D., Siskind, E. J., Spada, F., Spandre, G., Spinelli, P., Suson, D. J., Tajima, H., Tanaka, K., Thayer, J. B., Tibaldo, L., Torres, D. F., Troja, E., Uchiyama, Y., Vianello, G., Wood, K. S., Wood, M., Zaharijas, G., and Zimmer, S. The Fermi Galactic Center GeV excess and implications for dark matter. United States: N. p., 2017. Web. doi:10.3847/1538-4357/aa6cab.
Ackermann, M., Ajello, M., Albert, A., Atwood, W. B., Baldini, L., Ballet, J., Barbiellini, G., Bastieri, D., Bellazzini, R., Bissaldi, E., Blandford, R. D., Bloom, E. D., Bonino, R., Bottacini, E., Brandt, T. J., Bregeon, J., Bruel, P., Buehler, R., Burnett, T. H., Cameron, R. A., Caputo, R., Caragiulo, M., Caraveo, P. A., Cavazzuti, E., Cecchi, C., Charles, E., Chekhtman, A., Chiang, J., Chiappo, A., Chiaro, G., Ciprini, S., Conrad, J., Costanza, F., Cuoco, A., Cutini, S., D’Ammando, F., Palma, F. de, Desiante, R., Digel, S. W., Lalla, N. Di, Mauro, M. Di, Venere, L. Di, Drell, P. S., Favuzzi, C., Fegan, S. J., Ferrara, E. C., Focke, W. B., Franckowiak, A., Fukazawa, Y., Funk, S., Fusco, P., Gargano, F., Gasparrini, D., Giglietto, N., Giordano, F., Giroletti, M., Glanzman, T., Gomez-Vargas, G. A., Green, D., Grenier, I. A., Grove, J. E., Guillemot, L., Guiriec, S., Gustafsson, M., Harding, A. K., Hays, E., Hewitt, J. W., Horan, D., Jogler, T., Johnson, A. S., Kamae, T., Kocevski, D., Kuss, M., Mura, G. La, Larsson, S., Latronico, L., Li, J., Longo, F., Loparco, F., Lovellette, M. N., Lubrano, P., Magill, J. D., Maldera, S., Malyshev, D., Manfreda, A., Martin, P., Mazziotta, M. N., Michelson, P. F., Mirabal, N., Mitthumsiri, W., Mizuno, T., Moiseev, A. A., Monzani, M. E., Morselli, A., Negro, M., Nuss, E., Ohsugi, T., Orienti, M., Orlando, E., Ormes, J. F., Paneque, D., Perkins, J. S., Persic, M., Pesce-Rollins, M., Piron, F., Principe, G., Rainò, S., Rando, R., Razzano, M., Razzaque, S., Reimer, A., Reimer, O., Sánchez-Conde, M., Sgrò, C., Simone, D., Siskind, E. J., Spada, F., Spandre, G., Spinelli, P., Suson, D. J., Tajima, H., Tanaka, K., Thayer, J. B., Tibaldo, L., Torres, D. F., Troja, E., Uchiyama, Y., Vianello, G., Wood, K. S., Wood, M., Zaharijas, G., & Zimmer, S. The Fermi Galactic Center GeV excess and implications for dark matter. United States. doi:10.3847/1538-4357/aa6cab.
Ackermann, M., Ajello, M., Albert, A., Atwood, W. B., Baldini, L., Ballet, J., Barbiellini, G., Bastieri, D., Bellazzini, R., Bissaldi, E., Blandford, R. D., Bloom, E. D., Bonino, R., Bottacini, E., Brandt, T. J., Bregeon, J., Bruel, P., Buehler, R., Burnett, T. H., Cameron, R. A., Caputo, R., Caragiulo, M., Caraveo, P. A., Cavazzuti, E., Cecchi, C., Charles, E., Chekhtman, A., Chiang, J., Chiappo, A., Chiaro, G., Ciprini, S., Conrad, J., Costanza, F., Cuoco, A., Cutini, S., D’Ammando, F., Palma, F. de, Desiante, R., Digel, S. W., Lalla, N. Di, Mauro, M. Di, Venere, L. Di, Drell, P. S., Favuzzi, C., Fegan, S. J., Ferrara, E. C., Focke, W. B., Franckowiak, A., Fukazawa, Y., Funk, S., Fusco, P., Gargano, F., Gasparrini, D., Giglietto, N., Giordano, F., Giroletti, M., Glanzman, T., Gomez-Vargas, G. A., Green, D., Grenier, I. A., Grove, J. E., Guillemot, L., Guiriec, S., Gustafsson, M., Harding, A. K., Hays, E., Hewitt, J. W., Horan, D., Jogler, T., Johnson, A. S., Kamae, T., Kocevski, D., Kuss, M., Mura, G. La, Larsson, S., Latronico, L., Li, J., Longo, F., Loparco, F., Lovellette, M. N., Lubrano, P., Magill, J. D., Maldera, S., Malyshev, D., Manfreda, A., Martin, P., Mazziotta, M. N., Michelson, P. F., Mirabal, N., Mitthumsiri, W., Mizuno, T., Moiseev, A. A., Monzani, M. E., Morselli, A., Negro, M., Nuss, E., Ohsugi, T., Orienti, M., Orlando, E., Ormes, J. F., Paneque, D., Perkins, J. S., Persic, M., Pesce-Rollins, M., Piron, F., Principe, G., Rainò, S., Rando, R., Razzano, M., Razzaque, S., Reimer, A., Reimer, O., Sánchez-Conde, M., Sgrò, C., Simone, D., Siskind, E. J., Spada, F., Spandre, G., Spinelli, P., Suson, D. J., Tajima, H., Tanaka, K., Thayer, J. B., Tibaldo, L., Torres, D. F., Troja, E., Uchiyama, Y., Vianello, G., Wood, K. S., Wood, M., Zaharijas, G., and Zimmer, S. Thu . "The Fermi Galactic Center GeV excess and implications for dark matter". United States. doi:10.3847/1538-4357/aa6cab. https://www.osti.gov/servlets/purl/1355726.
@article{osti_1355726,
title = {The Fermi Galactic Center GeV excess and implications for dark matter},
author = {Ackermann, M. and Ajello, M. and Albert, A. and Atwood, W. B. and Baldini, L. and Ballet, J. and Barbiellini, G. and Bastieri, D. and Bellazzini, R. and Bissaldi, E. and Blandford, R. D. and Bloom, E. D. and Bonino, R. and Bottacini, E. and Brandt, T. J. and Bregeon, J. and Bruel, P. and Buehler, R. and Burnett, T. H. and Cameron, R. A. and Caputo, R. and Caragiulo, M. and Caraveo, P. A. and Cavazzuti, E. and Cecchi, C. and Charles, E. and Chekhtman, A. and Chiang, J. and Chiappo, A. and Chiaro, G. and Ciprini, S. and Conrad, J. and Costanza, F. and Cuoco, A. and Cutini, S. and D’Ammando, F. and Palma, F. de and Desiante, R. and Digel, S. W. and Lalla, N. Di and Mauro, M. Di and Venere, L. Di and Drell, P. S. and Favuzzi, C. and Fegan, S. J. and Ferrara, E. C. and Focke, W. B. and Franckowiak, A. and Fukazawa, Y. and Funk, S. and Fusco, P. and Gargano, F. and Gasparrini, D. and Giglietto, N. and Giordano, F. and Giroletti, M. and Glanzman, T. and Gomez-Vargas, G. A. and Green, D. and Grenier, I. A. and Grove, J. E. and Guillemot, L. and Guiriec, S. and Gustafsson, M. and Harding, A. K. and Hays, E. and Hewitt, J. W. and Horan, D. and Jogler, T. and Johnson, A. S. and Kamae, T. and Kocevski, D. and Kuss, M. and Mura, G. La and Larsson, S. and Latronico, L. and Li, J. and Longo, F. and Loparco, F. and Lovellette, M. N. and Lubrano, P. and Magill, J. D. and Maldera, S. and Malyshev, D. and Manfreda, A. and Martin, P. and Mazziotta, M. N. and Michelson, P. F. and Mirabal, N. and Mitthumsiri, W. and Mizuno, T. and Moiseev, A. A. and Monzani, M. E. and Morselli, A. and Negro, M. and Nuss, E. and Ohsugi, T. and Orienti, M. and Orlando, E. and Ormes, J. F. and Paneque, D. and Perkins, J. S. and Persic, M. and Pesce-Rollins, M. and Piron, F. and Principe, G. and Rainò, S. and Rando, R. and Razzano, M. and Razzaque, S. and Reimer, A. and Reimer, O. and Sánchez-Conde, M. and Sgrò, C. and Simone, D. and Siskind, E. J. and Spada, F. and Spandre, G. and Spinelli, P. and Suson, D. J. and Tajima, H. and Tanaka, K. and Thayer, J. B. and Tibaldo, L. and Torres, D. F. and Troja, E. and Uchiyama, Y. and Vianello, G. and Wood, K. S. and Wood, M. and Zaharijas, G. and Zimmer, S.},
abstractNote = {Here, the region around the Galactic Center (GC) is now well established to be brighter at energies of a few GeV than what is expected from conventional models of diffuse gamma-ray emission and catalogs of known gamma-ray sources. We study the GeV excess using 6.5 yr of data from the Fermi Large Area Telescope. We characterize the uncertainty of the GC excess spectrum and morphology due to uncertainties in cosmic-ray source distributions and propagation, uncertainties in the distribution of interstellar gas in the Milky Way, and uncertainties due to a potential contribution from the Fermi bubbles. We also evaluate uncertainties in the excess properties due to resolved point sources of gamma rays. The GC is of particular interest, as it would be expected to have the brightest signal from annihilation of weakly interacting massive dark matter (DM) particles. However, control regions along the Galactic plane, where a DM signal is not expected, show excesses of similar amplitude relative to the local background. Furthermore, based on the magnitude of the systematic uncertainties, we conservatively report upper limits for the annihilation cross-section as a function of particle mass and annihilation channel.},
doi = {10.3847/1538-4357/aa6cab},
journal = {The Astrophysical Journal (Online)},
number = 1,
volume = 840,
place = {United States},
year = {Thu May 04 00:00:00 EDT 2017},
month = {Thu May 04 00:00:00 EDT 2017}
}

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Cited by: 14works
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  • The region around the Galactic Center (GC) is now well established to be brighter at energies of a few GeV than what is expected from conventional models of diffuse gamma-ray emission and catalogs of known gamma-ray sources. We study the GeV excess using 6.5 yr of data from the Fermi Large Area Telescope. We characterize the uncertainty of the GC excess spectrum and morphology due to uncertainties in cosmic-ray source distributions and propagation, uncertainties in the distribution of interstellar gas in the Milky Way, and uncertainties due to a potential contribution from the Fermi bubbles. We also evaluate uncertainties inmore » the excess properties due to resolved point sources of gamma rays. The GC is of particular interest, as it would be expected to have the brightest signal from annihilation of weakly interacting massive dark matter (DM) particles. However, control regions along the Galactic plane, where a DM signal is not expected, show excesses of similar amplitude relative to the local background. Based on the magnitude of the systematic uncertainties, we conservatively report upper limits for the annihilation cross-section as a function of particle mass and annihilation channel.« less
  • The singlet-doublet fermion dark matter model (SDFDM) provides a good DM candidate as well as the possibility of generating neutrino masses radiatively. The search and identification of DM requires the combined effort of both indirect and direct DM detection experiments in addition to the LHC. Remarkably, an excess of GeV gamma rays from the Galactic Center (GCE) has been measured with the Fermi Large Area Telescope (LAT) which appears to be robust with respect to changes in the diffuse galactic background modeling. Although several astrophysical explanations have been proposed, DM remains a simple and well motivated alternative. In this work,more » we examine the sensitivities of dark matter searches in the SDFDM scenario using Fermi-LAT, CTA, IceCube/DeepCore, LUX, PICO and LHC with an emphasis on exploring the regions of the parameter space that can account for the GCE. We find that DM particles present in this model with masses close to ∼ 99 GeV and ∼ (173–190) GeV annihilating predominantly into the W{sup +}W{sup −} channel and t t-bar channel respectively, provide an acceptable fit to the GCE while being consistent with different current experimental bounds. We also find that much of the obtained parameter space can be ruled out by future direct search experiments like LZ and XENON-1T, in case of null results by these detectors. Interestingly, we show that the most recent data by LUX is starting to probe the best fit region in the SDFDM model.« less
  • We analyze publicly available Fermi-LAT high-energy gamma-ray data and confirm the existence of clear spectral feature peaked at E{sub γ} = 130 GeV. Scanning over the Galaxy we identify several disconnected regions where the observed excess originates from. Our best optimized fit is obtained for the central region of Galaxy with a clear peak at 130 GeV with local statistical significance 4.5σ. The observed excess is not correlated with Fermi bubbles. We compute the photon spectra induced by dark matter annihilations into two and four standard model particles, the latter via two light intermediate states, and fit the spectra withmore » data. Since our fits indicate sharper and higher signal peak than in the previous works, data favors dark matter direct two-body annihilation channels into photons or other channels giving only line-like spectra. If Einasto halo profile correctly predicts the central cusp of Galaxy, dark matter annihilation cross-section to two photons is of order ten percent of the standard thermal freeze-out cross-section. The large dark matter two-body annihilation cross-section to photons may signal a new resonance that should be searched for at the CERN LHC experiments.« less
  • We show that the GeV scale γ-ray excess from the direction of the Galactic Center can be naturally explained by the pair annihilation of Abelian vector dark matter (VDM) into a pair of dark Higgs bosons (VV→ φ φ), followed by the subsequent decay of φ into b b-bar or τ τ-bar  . All the processes are described by a renormalizable VDM model with the Higgs portal, which is naturally flavor-dependent. Some parameter space of this scenario can be tested at the near future direct dark matter search experiments such as LUX and XENON1T.