High-energy tail of the Galactic Center gamma-ray excess
Observations by the Fermi-LAT have uncovered a bright, spherically symmetric excess surrounding the center of the Milky Way Galaxy. The spectrum of the γ-ray excess peaks sharply at an energy ∼2 GeV, exhibiting a hard spectrum at lower energies, and falls off quickly above an energy ∼5 GeV. The sp...
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| Format: | Article |
| Language: | English |
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American Physical Society
2017
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| Online Access: | http://hdl.handle.net/1721.1/110221 https://orcid.org/0000-0003-3472-7606 https://orcid.org/0000-0001-9531-1319 https://orcid.org/0000-0001-9699-9047 |
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| author | Linden, Tim Rodd, Nicholas Llewellyn Safdi, Benjamin Ryan Slatyer, Tracy Robyn |
| author2 | Massachusetts Institute of Technology. Center for Theoretical Physics |
| author_facet | Massachusetts Institute of Technology. Center for Theoretical Physics Linden, Tim Rodd, Nicholas Llewellyn Safdi, Benjamin Ryan Slatyer, Tracy Robyn |
| author_sort | Linden, Tim |
| collection | MIT |
| description | Observations by the Fermi-LAT have uncovered a bright, spherically symmetric excess surrounding the center of the Milky Way Galaxy. The spectrum of the γ-ray excess peaks sharply at an energy ∼2 GeV, exhibiting a hard spectrum at lower energies, and falls off quickly above an energy ∼5 GeV. The spectrum of the excess above ∼10 GeV is potentially an important discriminator between different physical models for its origin. We focus our study on observations of the γ-ray excess at energies exceeding 10 GeV, finding: (1) a statistically significant excess remains in the energy range 9.5–47.5 GeV, which is not degenerate with known diffuse emission templates such as the Fermi bubbles, (2) the radial profile of the excess at high energies remains relatively consistent with data near the spectral peak (3) the data above ∼5 GeV prefer a slightly greater ellipticity with a major axis oriented perpendicular to the Galactic plane. Using the recently developed non-Poissonian template fit, we find mild evidence for a point-source origin for the high-energy excess, although given the statistical and systematic uncertainties we show that a smooth origin of the high-energy emission cannot be ruled out. We discuss the implication of these findings for pulsar and dark matter models of the γ-ray excess. Finally we provide a number of updated measurements of the γ-ray excess, utilizing novel diffuse templates and the Pass 8 data set. |
| first_indexed | 2024-09-23T10:03:33Z |
| format | Article |
| id | mit-1721.1/110221 |
| institution | Massachusetts Institute of Technology |
| language | English |
| last_indexed | 2024-09-23T10:03:33Z |
| publishDate | 2017 |
| publisher | American Physical Society |
| record_format | dspace |
| spelling | mit-1721.1/1102212022-09-26T15:28:14Z High-energy tail of the Galactic Center gamma-ray excess Linden, Tim Rodd, Nicholas Llewellyn Safdi, Benjamin Ryan Slatyer, Tracy Robyn Massachusetts Institute of Technology. Center for Theoretical Physics Rodd, Nicholas Llewellyn Safdi, Benjamin Ryan Slatyer, Tracy Robyn Observations by the Fermi-LAT have uncovered a bright, spherically symmetric excess surrounding the center of the Milky Way Galaxy. The spectrum of the γ-ray excess peaks sharply at an energy ∼2 GeV, exhibiting a hard spectrum at lower energies, and falls off quickly above an energy ∼5 GeV. The spectrum of the excess above ∼10 GeV is potentially an important discriminator between different physical models for its origin. We focus our study on observations of the γ-ray excess at energies exceeding 10 GeV, finding: (1) a statistically significant excess remains in the energy range 9.5–47.5 GeV, which is not degenerate with known diffuse emission templates such as the Fermi bubbles, (2) the radial profile of the excess at high energies remains relatively consistent with data near the spectral peak (3) the data above ∼5 GeV prefer a slightly greater ellipticity with a major axis oriented perpendicular to the Galactic plane. Using the recently developed non-Poissonian template fit, we find mild evidence for a point-source origin for the high-energy excess, although given the statistical and systematic uncertainties we show that a smooth origin of the high-energy emission cannot be ruled out. We discuss the implication of these findings for pulsar and dark matter models of the γ-ray excess. Finally we provide a number of updated measurements of the γ-ray excess, utilizing novel diffuse templates and the Pass 8 data set. United States. Department of Energy (contract DE-SC00012567) United States. Department of Energy (contract DE-SC0013999) 2017-06-23T18:03:54Z 2017-06-23T18:03:54Z 2016-11 2016-04 2016-11-30T23:00:08Z Article http://purl.org/eprint/type/JournalArticle 2470-0010 2470-0029 http://hdl.handle.net/1721.1/110221 Linden, Tim; Rodd, Nicholas L.; Safdi, Benjamin R. and Slatyer, Tracy R. "High-energy tail of the Galactic Center gamma-ray excess." Physical Review D 94, 103013 (November 2016): 1-39 © 2016 American Physical Society https://orcid.org/0000-0003-3472-7606 https://orcid.org/0000-0001-9531-1319 https://orcid.org/0000-0001-9699-9047 en http://dx.doi.org/10.1103/PhysRevD.94.103013 Physical Review D Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use. American Physical Society application/pdf American Physical Society American Physical Society |
| spellingShingle | Linden, Tim Rodd, Nicholas Llewellyn Safdi, Benjamin Ryan Slatyer, Tracy Robyn High-energy tail of the Galactic Center gamma-ray excess |
| title | High-energy tail of the Galactic Center gamma-ray excess |
| title_full | High-energy tail of the Galactic Center gamma-ray excess |
| title_fullStr | High-energy tail of the Galactic Center gamma-ray excess |
| title_full_unstemmed | High-energy tail of the Galactic Center gamma-ray excess |
| title_short | High-energy tail of the Galactic Center gamma-ray excess |
| title_sort | high energy tail of the galactic center gamma ray excess |
| url | http://hdl.handle.net/1721.1/110221 https://orcid.org/0000-0003-3472-7606 https://orcid.org/0000-0001-9531-1319 https://orcid.org/0000-0001-9699-9047 |
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