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In an attempt to constrain and understand the emission mechanism of gamma rays, we perform a cross-correlation analysis of 15 blazars using light curves in millimetre, optical and gamma rays. We use discrete correlation function and…

High Energy Astrophysical Phenomena · Physics 2015-12-15 V. Ramakrishnan , T. Hovatta , M. Tornikoski , K. Nilsson , E. Lindfors , M. Baloković , A. Lähteenmäki , R. Reinthal , L. Takalo

We first report GeV $\gamma$-ray emission from supernova remnant (SNR) G15.9+0.2 in this work. The results show that its power-law spectral index is 2.94$\pm$0.25 with a 6.47$\sigma$ significance level, and the $\gamma$-ray emission can be…

High Energy Astrophysical Phenomena · Physics 2021-10-27 Yunchuan Xiang , Zejun Jiang , Mengyao Tang

High-energy solar flares have shown to have at least two distinct phases: prompt-impulsive and delayed-gradual. Identifying the mechanism responsible for accelerating the electrons and ions and the site at which it occurs during these two…

Solar and Stellar Astrophysics · Physics 2021-09-29 Melissa Pesce-Rollins , Nicola Omodei , Vahe' Petrosian , Francesco Longo

It is difficult to distinguish hadronic process from the leptonic one in $\gamma$-ray observation, which is however crucial in revealing the origin of cosmic rays. As an endeavor in the regard, we focus in this work on the complex…

High Energy Astrophysical Phenomena · Physics 2022-06-08 Xiao Zhang , Yang Chen , Fa-xiang Zheng , Qian-cheng Liu , Ping Zhou , Bing Liu

The Fermi Large Area Telescope (LAT) has been surveying the sky in gamma rays from 30 MeV to more than 300 GeV since August 2008. Fermi is the only mission able to detect high energy > few hundreds MeV emission from the Sun during the new…

High Energy Astrophysical Phenomena · Physics 2019-08-15 G. Iafrate , F. Longo

This Letter presents the first results from the observations of LSI +61 303 using Large Area Telescope data from the Fermi Gamma-Ray Space Telescope between 2008 August and 2009 March. Our results indicate variability that is consistent…

High Energy Astrophysical Phenomena · Physics 2019-08-13 A. A. Abdo

Context. More than one hundred GeV pulsars have been detected up to now by the LAT telescope on the Fermi gamma-ray observatory, showing peak energies around a few GeV. Current modelling proposes that the high energy emission comes from…

High Energy Astrophysical Phenomena · Physics 2015-06-11 Ioanna Arka , Guillaume Dubus

The discovery of bright gamma-ray emission coincident with supernova remnant (SNR) W51C is reported using the Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope. W51C is a middle-aged remnant (~10^4 yr) with intense…

High Energy Astrophysical Phenomena · Physics 2012-08-27 Fermi LAT collaboration

We present results from {\gamma}-ray observations of the Coma cluster incorporating 6 years of Fermi-LAT data and the newly released {\emph{Pass 8}} event-level analysis. Our analysis of the region reveals low-significance residual…

High Energy Astrophysical Phenomena · Physics 2016-03-10 LAT Collaboration , Y. Rephaeli

Recent observations of Gamma-Ray Bursts (GRBs) by the Fermi Large Area Telescope (LAT) revealed a power law decay feature of the high energy emission (above 100 MeV), which led to the suggestion that it originates from a (probably…

High Energy Astrophysical Phenomena · Physics 2015-05-20 Amanda Maxham , Bin-Bin Zhang , Bing Zhang

The MAGIC telescopes discovered very high energy (VHE, E>100 GeV) gamma-ray emission coming from the distant Flat Spectrum Radio Quasar (FSRQ) PKS 1222+21 (4C +21.35, z=0.432). It is the second most distant VHE gamma-ray source, with well…

High Energy Astrophysical Phenomena · Physics 2019-08-13 J. Becerra-González , A. Stamerra , K. Saito , D. Mazin , F. Tavecchio , L. Maraschi , E. Prandini , J. Sitarek , K. Berger

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 very high energy (VHE; >100 GeV) source HESS J0632+057 has been recently confirmed as a \gamma-ray binary, a subclass of the high mass X-ray binary (HMXB) population, through the detection of an orbital period of 321 days. We performed…

We report the first detection of GeV gamma-ray flaring activity from the compact symmetric object (CSO)-like source 4C 76.03, based on 17 years of Fermi-LAT observations. Its long-term, time-averaged gamma-ray properties are consistent with…

High Energy Astrophysical Phenomena · Physics 2026-03-24 Xiong Jiang , Hai Lei , Hao-Yi Huang , Wei Zhang , Yang-Ji Li , Da-Ming Wei

We present a detailed study of the gamma-ray emission from the direction of the star-forming region W30 based on a decade of the Fermi Large Area Telescope data in the 0.3-300 GeV photon energy range. The morphological and spectral analyses…

High Energy Astrophysical Phenomena · Physics 2019-08-21 Bing Liu , Rui-zhi Yang , Xiao-na Sun , Felix Aharonian , Yang Chen

We examine 288 GRBs detected by the Fermi Gamma-ray Space Telescope's Gamma-ray Burst Monitor (GBM) that fell within the field-of-view of Fermi's Large Area Telescope (LAT) during the first 2.5 years of observations, which showed no…

High Energy Astrophysical Phenomena · Physics 2015-06-03 LAT Collaboration , GBM Collaboration

We report the discovery of gamma-ray detection from the Large Magellanic Cloud (LMC) B0443-6657 using the Large Area Telescope (LAT) on board the \textit{Fermi Gamma-ray Space Telescope}. LMC B0443-6657 is a flat spectrum radio source,…

High Energy Astrophysical Phenomena · Physics 2018-01-08 Qing-Wen Tang

We report the first detection of >100 MeV gamma rays associated with a behind-the-limb solar flare, which presents a unique opportunity to probe the underlying physics of high-energy flare emission and particle acceleration. On 2013 October…

Solar and Stellar Astrophysics · Physics 2015-06-03 Melissa Pesce-Rollins , Nicola Omodei , Vahe' Petrosian , Wei Liu , Fatima Rubio da Costa , Alice Allafort , Qingrong Chen

The detection of diffuse radio emission associated with clusters of galaxies indicates populations of relativistic leptons infusing the intracluster medium. Those electrons and positrons are either injected into and accelerated directly in…

High Energy Astrophysical Phenomena · Physics 2015-05-19 M. Ackermann et al.

Recently, tentative evidence for an excess of gamma rays at energies around 130 GeV has been reported from analyses of data from the Fermi Large Area Telescope (LAT). The excess is potentially of great interest, as it could be associated…

High Energy Astrophysical Phenomena · Physics 2012-07-04 Stefano Profumo , Tim Linden