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We report the Fermi-LAT discovery of high-energy (MeV/GeV) gamma-ray emission positionally consistent with the center of the radio galaxy M87, at a source significance of over 10 sigma in ten-months of all-sky survey data. Following the…

High Energy Astrophysical Phenomena · Physics 2009-12-04 The Fermi LAT Collaboration , A. A. Abdo , D. E. Harris , F. Massaro , L. Stawarz

The launch of the Fermi satellite in 2008, with its Large Area Telescope (LAT) on board, has opened a new era for the study of gamma-ray sources at GeV ($10^9$ eV) energies. Similarly, the commissioning of the third generation of imaging…

Instrumentation and Methods for Astrophysics · Physics 2023-11-07 Denys Malyshev , Lars Mohrmann

Classical Novae were revealed as a surprise source of gamma-rays in Fermi LAT observations. During the first 8 years since the LAT was launched, 6 novae in total have been detected to > 5 sigma in gamma-rays, in contrast to the 69…

High Energy Astrophysical Phenomena · Physics 2017-04-03 Paul J. Morris , Garret Cotter , Anthony M. Brown , Paula M. Chadwick

We present an incremental version (4FGL-DR2, for Data Release 2) of the fourth Fermi-LAT catalog of gamma-ray sources. Based on the first ten years of science data in the energy range from 50 MeV to 1 TeV, it uses the same analysis methods…

High Energy Astrophysical Phenomena · Physics 2020-12-18 J. Ballet , T. H. Burnett , S. W. Digel , B. Lott

We present the analysis of Fermi Large Area Telecope (LAT) data of the gamma-ray emission in the vicinity of a radio supernova remnant (SNR), G045.7$-$00.4. To study the origin of the gamma-ray emission, we also make use of the CO survey…

High Energy Astrophysical Phenomena · Physics 2022-07-12 Hai-Ming Zhang , Ruo-Yu Liu , Yang Su , Hui Zhu , Shao-Qiang Xi , Xiang-Yu Wang

The recent detection of extended $\gamma$-ray emission around middle-aged pulsars is interpreted as inverse-Compton scattering of ambient photons by electron-positron pairs escaping the pulsar wind nebula, which are confined near the system…

High Energy Astrophysical Phenomena · Physics 2024-11-12 S. Abdollahi , F. Acero , A. Acharyya , A. Adelfio , M. Ajello , L. Baldini , J. Ballet , C. Bartolini , J. Becerra Gonzalez , R. Bellazzini , E. Bissaldi , R. Bonino , P. Bruel , R. A. Cameron , P. A. Caraveo , D. Castro , E. Cavazzuti , C. C. Cheung , N. Cibrario , S. Ciprini , G. Cozzolongo , P. Cristarella Orestano , A. Cuoco , S. Cutini , F. D'Ammando , N. Di Lalla , A. Dinesh , L. Di Venere , A. Domínguez , A. Fiori , S. Funk , P. Fusco , F. Gargano , C. Gasbarra , D. Gasparrini , S. Germani , F. Giacchino , N. Giglietto , M. Giliberti , F. Giordano , M. Giroletti , D. Green , I. A. Grenier , L. Guillemot , S. Guiriec , R. Gupta , M. Hashizume , E. Hays , J. W. Hewitt , D. Horan , X. Hou , T. Kayanoki , M. Kuss , A. Laviron , M. Lemoine-Goumard , A. Liguori , J. Li , I. Liodakis , P. Loizzo , F. Longo , F. Loparco , L. Lorusso , M. N. Lovellette , P. Lubrano , S. Maldera , D. Malyshev , G. Martí-Devesa , P. Martin , M. N. Mazziotta , I. Mereu , P. F. Michelson , N. Mirabal , W. Mitthumsiri , T. Mizuno , P. Monti-Guarnieri , M. E. Monzani , A. Morselli , I. V. Moskalenko , M. Negro , N. Omodei , M. Orienti , E. Orlando , D. Paneque , G. Panzarini , M. Persic , M. Pesce-Rollins , R. Pillera , T. A. Porter , S. Rainò , R. Rando , M. Razzano , A. Reimer , O. Reimer , M. Rocamora Bernal , M. Sánchez-Conde , P. M. Saz Parkinson , D. Serini , C. Sgrò , E. J. Siskind , D. A. Smith , G. Spandre , P. Spinelli , A. W. Strong , D. J. Suson , H. Tajima , J. B. Thayer , D. F. Torres , J. Valverde , Z. Wadiasingh , K. Wood , G. Zaharijas

We use the number counts of X-ray selected normal galaxies to explore their evolution by combining the most recent wide-angle shallow and pencil-beam deep samples available. The differential X-ray number counts, dN/dS, for early and…

Astrophysics · Physics 2009-11-11 A. Georgakakis , I. Georgantopoulos , A. Akylas , A. Zezas , P. Tzanavaris

Using gamma-ray data from the Fermi Large Area Telescope, various groups have identified a clear excess emission in the Inner Galaxy, at energies around a few GeV. This excess resembles remarkably well a signal from dark-matter…

High Energy Astrophysical Phenomena · Physics 2016-03-10 Richard Bartels , Suraj Krishnamurthy , Christoph Weniger

With almost 15 years of data taken by the Large Area Telescope (LAT) onboard the Fermi satellite we discovered an extended source of GeV emission in the region of the very-high-energy (TeV) source 1LHAASO J1945+2424. This TeV source is more…

High Energy Astrophysical Phenomena · Physics 2023-12-05 Miguel Araya , J. A. Álvarez-Quesada

Dark matter annihilations taking place in nearby subhalos could appear as gamma-ray sources without detectable counterparts at other wavelengths. In this study, we consider the collection of unassociated gamma-ray sources reported by the…

High Energy Astrophysical Phenomena · Physics 2015-12-23 Bridget Bertoni , Dan Hooper , Tim Linden

A significant point-like component from the small scale (or discrete) structure in the H2 interstellar gas might be present in the Fermi-LAT data, but modeling this emission relies on observations of rare gas tracers only available in…

High Energy Astrophysical Phenomena · Physics 2023-03-29 Alexander Shmakov , Mohammadamin Tavakoli , Pierre Baldi , Christopher M. Karwin , Alex Broughton , Simona Murgia

The extragalactic sources of ultra-high-energy (E > 4x10^19 eV) cosmic rays that make a small contribution to the flux of particles recorded by ground-based arrays are discussed. We show that cosmic rays from such sources can produce a…

High Energy Astrophysical Phenomena · Physics 2019-01-09 Anna Uryson

Gamma rays from extragalactic sources are attenuated by pair-production interactions with diffuse photons of the extragalactic background light (EBL). Gamma-ray bursts (GRBs) are a source of high-redshift photons above 10 GeV, and could be…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-14 Rudy C. Gilmore , Francisco Prada , Joel R. Primack

The prevalent view that the radio-loud gamma-ray pulsars have gamma-ray luminosities that exceed their radio luminosities by several orders of magnitude is based on the assumption that the decay with distance of their gamma-ray fluxes obeys…

High Energy Astrophysical Phenomena · Physics 2023-03-02 Houshang Ardavan

We study the origin of the extragalactic diffuse gamma-ray background using the data from the Fermi telescope. To estimate the background level, we count photons at high Galactic latitudes |b|>60 degrees. Subtracting photons associated to…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-27 A. Neronov , D. V. Semikoz

We report evidence for extended gamma-ray emission from the Virgo, Fornax and Coma clusters based on a maximum-likelihood analysis of the 3-year Fermi-LAT data. For all three clusters, excess emission is observed within three degrees of the…

High Energy Astrophysical Phenomena · Physics 2015-06-12 Jiaxin Han , Carlos S. Frenk , Vincent R. Eke , Liang Gao , Simon D. M. White

G279.0+1.1 is a supernova remnant (SNR) with poorly known parameters, first detected as a dim radio source and classified as an evolved system. An analysis of data from the Fermi-LAT revealing for the first time an extended source of gamma…

High Energy Astrophysical Phenomena · Physics 2020-02-05 Miguel Araya

In this paper we report the Fermi Large Area Telescope (LAT) detection of the gamma-ray emission toward the young star forming region W43. Using the latest source catalog and diffuse background models, the extended gamma-ray excess is…

High Energy Astrophysical Phenomena · Physics 2020-08-19 Rui-zhi Yang , Yuan Wang

Previously, we have shown in Li et al. (2018) that very weak $\gamma$-ray excesses ($\sim 2\sigma$) appear in some Milky Way dwarf spheroidal galaxies (dSphs, including candidates) and the combination analysis of 12 nearby dSphs yields a…

High Energy Astrophysical Phenomena · Physics 2021-11-10 Shang Li , Yun-Feng Liang , Yi-Zhong Fan

We report the detection of pulsed gamma-rays from the young, spin-powered radio pulsar PSR J2021+3651 using data acquired with the Large Area Telescope (LAT) on the Fermi Gamma-ray Space Telescope (formerly GLAST). The light curve consists…

High Energy Astrophysical Phenomena · Physics 2009-07-22 A. A. Abdo