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The extreme variability of blazars, in both timescale and amplitude, is generally explained as the effect of a relativistic jet closely aligned to the observer's line-of-sight. Due to causality arguments, variability characteristics…

The inner region of the Milky Way is one of the most interesting and complex regions of the gamma-ray sky. The intense interstellar emission and resolved point sources, as well as potential contributions by other sources such as unresolved…

High Energy Astrophysical Phenomena · Physics 2019-08-13 Troy A. Porter , Simona Murgia

The Fermi satellite has a particular motion during its flight which enables it to catch the gamma-ray bursts mostly well. The side-effect of this favourable feature is that the lightcurves of the GBM detectors are stressed by rapidly and…

High Energy Astrophysical Phenomena · Physics 2012-02-14 Dorottya Szecsi , Zsolt Bagoly , Istvan Horvath , Lajos G. Balazs , Peter Veres , Attila Meszaros

Gamma-ray Astronomy studies cosmic accelerators through their electromagnetic radiation in the energy range between ~100 MeV and ~100 TeV. The present most sensitive observations in this energy band are performed, from space, by the Large…

High Energy Astrophysical Phenomena · Physics 2011-11-29 Javier Rico

We describe the optical spectropolarimetric monitoring program at Steward Observatory centered around gamma-ray-bright blazars and the LAT Monitored Source List planned for Fermi Cycles 2-4. The large number of measurements made during…

High Energy Astrophysical Phenomena · Physics 2009-12-21 P. S. Smith , E. Montiel , S. Rightley , J. Turner , G. D. Schmidt , B. T. Jannuzi

Context. We present the light curves of six BL Lac objects, PKS 0537-441, PKS 0735+17, OJ 287, PKS 2005-489, PKS 2155-304, W Comae, and of the flat spectrum radio quasar PKS 1510-089, as a part of a photometric monitoring program in the…

High Energy Astrophysical Phenomena · Physics 2015-06-16 Angela Sandrinelli , Stefano Covino , Aldo Treves

S5 0716+714 is a well-studied BL Lac object in the sky. Verifying the existence of correlations among the flux variations in different bands serves as an important tool to investigate the emission processes. To examine the possible…

High Energy Astrophysical Phenomena · Physics 2015-05-18 Bingkai Zhang , Benzhong Dai , Li Zhang , Jiali Liu , Zhen Cao

The Fermi Large Area Telescope, in collaboration with several groups from the radio community, have had marvellous success at uncovering new gamma-ray millisecond pulsars (MSPs). In fact, MSPs now make up a sizable fraction of the total…

High Energy Astrophysical Phenomena · Physics 2015-05-19 C. Venter , A. K. Harding , T. J. Johnson

The Fermi All-sky Variability Analysis (FAVA) provides a photometric alternative for identifying week-long gamma-ray flares across the entire sky while being independent of any diffuse Galactic or isotropic emission model. We reviewed 779…

High Energy Astrophysical Phenomena · Physics 2024-02-29 Scott D. Joffre , Núria Torres-Albà , Marco Ajello , Daniel Kocevski , Rolf Buehler

Measurements of the spectrum of the fluctuations of the output current of the quadratic detector of a telescope can be used to find unresolved astronomical gravitational lenses and determine time delays between their image components. These…

Astrophysics · Physics 2009-11-13 Ermanno F. Borra

In a previous paper, we studied two statistical methods used to analyse the variability of active galactic nuclei (AGNs): the C and F statistics. Applying them to observed differential light-curves of 39 AGNs, we found that, even though the…

Astrophysics of Galaxies · Physics 2020-09-02 L. Zibecchi , I. Andruchow , S. A. Cellone , D. D. Carpintero

The impact of the Fermi Gamma-ray Space Telescope on blazar research is reviewed. This includes a brief description of the Fermi Large Area Telescope, a summary of the various classes of extragalactic sources found in the First Large Area…

High Energy Astrophysical Phenomena · Physics 2019-08-13 Charles D. Dermer

We describe an ongoing optical spectrophotometric monitoring program of a sample of Fermi/LAT bright sources showing prominent and variable {\gamma}-ray emission, with the 2.1m telescope at Observatorio Astrof\'isico Guillermo Haro (OAGH)…

High Energy Astrophysical Phenomena · Physics 2013-04-19 V. Patiño-Álvarez , V. Chavushyan , J. León-Tavares , J. R. Valdés , A. Carramiñana , L. Carrasco , J. Torrealba

The Large Area Telescope (LAT) on board the \emph{Fermi} Gamma-ray Space Telescope has been continuously providing good quality survey data of the entire sky in the high energy range from 30 MeV to 500 GeV and above since August 2008. A…

High Energy Astrophysical Phenomena · Physics 2025-10-13 A. Pathania , K. K. Singh , S. K. Singh , A. Tolamatti , B. B. Singh , K. K. Yadav

The Large Area Telescope (LAT) onboard the Fermi Gamma-ray Space Telescope detected a gamma-ray source that is spatially consistent with the location of Eta Carinae. This source has been persistently bright since the beginning of the LAT…

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

All-sky explorations by Fermi-LAT have revolutionized our view of the gamma-ray sky. While its ongoing all-sky survey counts thousands of sources, essential issues related to the nature of unassociated sources call for sensitive all-sky…

High Energy Astrophysical Phenomena · Physics 2016-06-22 Eugenio Bottacini , Marco Ajello

Recent results on particle momentum and spin correlations are discussed in view of the role played by the effects of quantum statistics, including multiboson and coherence phenomena, and final state interaction. Particularly, it is…

Nuclear Theory · Physics 2009-11-10 R. Lednicky

Microvariability consists in small time scale variations of low amplitude in the photometric light curves of quasars, and represents an important tool to investigate their inner core. Detection of quasar microvariations is challenging for…

Instrumentation and Methods for Astrophysics · Physics 2016-08-08 J. A. de Diego , J. Polednikova , A. Bongiovanni , A. M. Pérez García , M. A. De Leo , T. Verdugo , J. Cepa

We present a new method to interpret the $\gamma$-ray data of our inner Galaxy as measured by the Fermi Large Area Telescope (Fermi LAT). We train and test convolutional neural networks with simulated Fermi-LAT images based on models tuned…

High Energy Astrophysical Phenomena · Physics 2018-05-29 Sascha Caron , Germán A. Gómez-Vargas , Luc Hendriks , Roberto Ruiz de Austri

A large sample of known and likely gamma-ray blazars has been monitored twice per week since late 2007 at 15 GHz with the Owens Valley Radio Observatory (OVRO) 40-meter Telescope. The sample contains about 1700 sources, including the…

High Energy Astrophysical Phenomena · Physics 2012-05-03 W. Max-Moerbeck , J. L. Richards , V. Pavlidou , T. Hovatta , O. G. King , T. J. Pearson , A. C. S. Readhead , R. Reeves , M. C. Shepherd