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Article: Searching for GeV gamma-ray emission from the bulge of M31

TitleSearching for GeV gamma-ray emission from the bulge of M31
Authors
KeywordsGamma-rays: galaxies
Galaxies: individual (M31)
Issue Date2019
PublisherInstitute of Physics Publishing Ltd. The Journal's web site is located at http://iopscience.iop.org/1674-4527/
Citation
Research in Astronomy and Astrophysics, 2019, v. 19 n. 3, article no. 46, p. 1-17 How to Cite?
AbstractThe three major large-scale, diffuse gamma-ray structures of the Milky Way are the Galactic disk, a bulge-like GeV excess towards the Galactic center, and the Fermi bubble. Whether such structures can also be present in other normal galaxies remains an open question. M31, as the nearest massive normal galaxy, holds promise for spatially-resolving the gamma-ray emission. Based on more than 8 years of Fermi-LAT observations, we use (1) disk, (2) bulge, and (3) disk-plus-bulge templates to model the spatial distribution of the gamma-ray emission from M31. Among these, the disk-plus-bulge template delivers the best-fit, in which the bulge component has a TS value 25.7 and a photon-index of 2.57 +/- 0.17, providing strong evidence for a centrally-concentrated gamma-ray emission from M31, that is analogous to the Galactic center excess. The total 0.2-300 GeV gamma-ray luminosity from this bulge component is (1.16 +/- 0.14) x 10(38) erg s(-1), which would require similar to 1.5 x 10(5) millisecond pulsars, if they were the dominant source. We also search for a Fermi bubble-like structure in M31 using the full dataset (pass8), but no significant evidence has been found. In addition, a likelihood analysis using only photons with the most accurate reconstructed direction (i.e., PSF3-only data) reveals a 4.8 sigma point-like source located at similar to 10 kpc to the northwest of the M31 disk, with a luminosity of (0.97 +/- 0.27) x 10(38) erg s(-1) and a photon-index of 2.31 +/- 0.18. Lacking a counterpart on the southeast side of the disk, the relation between this point-like source and a bubble-like structure remains elusive.
Persistent Identifierhttp://hdl.handle.net/10722/269455
ISSN
2021 Impact Factor: 1.889
2020 SCImago Journal Rankings: 0.516
ISI Accession Number ID
Grants

 

DC FieldValueLanguage
dc.contributor.authorFeng, L-
dc.contributor.authorLi, ZY-
dc.contributor.authorSu, M-
dc.contributor.authorTam, PHT-
dc.contributor.authorChen, Y-
dc.date.accessioned2019-04-24T08:08:03Z-
dc.date.available2019-04-24T08:08:03Z-
dc.date.issued2019-
dc.identifier.citationResearch in Astronomy and Astrophysics, 2019, v. 19 n. 3, article no. 46, p. 1-17-
dc.identifier.issn1674-4527-
dc.identifier.urihttp://hdl.handle.net/10722/269455-
dc.description.abstractThe three major large-scale, diffuse gamma-ray structures of the Milky Way are the Galactic disk, a bulge-like GeV excess towards the Galactic center, and the Fermi bubble. Whether such structures can also be present in other normal galaxies remains an open question. M31, as the nearest massive normal galaxy, holds promise for spatially-resolving the gamma-ray emission. Based on more than 8 years of Fermi-LAT observations, we use (1) disk, (2) bulge, and (3) disk-plus-bulge templates to model the spatial distribution of the gamma-ray emission from M31. Among these, the disk-plus-bulge template delivers the best-fit, in which the bulge component has a TS value 25.7 and a photon-index of 2.57 +/- 0.17, providing strong evidence for a centrally-concentrated gamma-ray emission from M31, that is analogous to the Galactic center excess. The total 0.2-300 GeV gamma-ray luminosity from this bulge component is (1.16 +/- 0.14) x 10(38) erg s(-1), which would require similar to 1.5 x 10(5) millisecond pulsars, if they were the dominant source. We also search for a Fermi bubble-like structure in M31 using the full dataset (pass8), but no significant evidence has been found. In addition, a likelihood analysis using only photons with the most accurate reconstructed direction (i.e., PSF3-only data) reveals a 4.8 sigma point-like source located at similar to 10 kpc to the northwest of the M31 disk, with a luminosity of (0.97 +/- 0.27) x 10(38) erg s(-1) and a photon-index of 2.31 +/- 0.18. Lacking a counterpart on the southeast side of the disk, the relation between this point-like source and a bubble-like structure remains elusive.-
dc.languageeng-
dc.publisherInstitute of Physics Publishing Ltd. The Journal's web site is located at http://iopscience.iop.org/1674-4527/-
dc.relation.ispartofResearch in Astronomy and Astrophysics-
dc.rightsResearch in Astronomy and Astrophysics. Copyright © Institute of Physics Publishing Ltd.-
dc.rightsThis is an author-created, un-copyedited version of an article published in Research in Astronomy and Astrophysics. IOP Publishing Ltd is not responsible for any errors or omissions in this version of the manuscript or any version derived from it. The Version of Record is available online at http://dx.doi.org/10.1088/1674-4527/19/3/46.-
dc.subjectGamma-rays: galaxies-
dc.subjectGalaxies: individual (M31)-
dc.titleSearching for GeV gamma-ray emission from the bulge of M31-
dc.typeArticle-
dc.identifier.emailSu, M: mengsu84@hku.hk-
dc.identifier.authoritySu, M=rp02150-
dc.description.naturelink_to_subscribed_fulltext-
dc.identifier.doi10.1088/1674-4527/19/3/46-
dc.identifier.scopuseid_2-s2.0-85065074860-
dc.identifier.hkuros297559-
dc.identifier.volume19-
dc.identifier.issue3-
dc.identifier.spagearticle no. 46, p. 1-
dc.identifier.epagearticle no. 46, p. 17-
dc.identifier.isiWOS:000462485200016-
dc.publisher.placeUnited Kingdom-
dc.relation.projectProbing the Gamma-ray Sky with Chinese Dark Matter Particle Explorer-
dc.identifier.issnl1674-4527-

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