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We present here the results of the analysis of the $\gamma$-ray blazar, 1ES 1215+303, over a 10-year period, from 2008 to 2017, measured at high energies (HE; 200 MeV $< E <$ 100 GeV) by the Fermi Large Area Telescope (LAT) and at very high…

High Energy Astrophysical Phenomena · Physics 2017-12-19 Janeth Valverde , Deirdre Horan , Giuliana Noto , Reshmi Mukherjee , Denis Bernard

We report on OVRO, WISE, Swift and Fermi-LAT observations of the high redshift blazar CGRaBS J0733+0456, from which significant flux variations in radio, infrared (IR) as well as $\gamma$-ray domains are detected. Particularly, the…

High Energy Astrophysical Phenomena · Physics 2019-07-10 Neng-Hui Liao , Li-Ming Dou , Ning Jiang , Yi-Bo Wang , Yi-Zhong Fan , Ting-Gui Wang

A large sample of blazar from the Candidate Gamma Ray Blazar Survey (CGRaBS) has been observed with the Owens Valley Radio Observatory (OVRO) 40-Meter Telescope at 15GHz. Using these quasi-simultaneous observations, we study the connection…

Cosmology and Nongalactic Astrophysics · Physics 2019-08-15 Walter Max-Moerbeck

Almost 10 yr of $\gamma$-ray observations with the Fermi Large Area Telescope (LAT) have revealed extreme $\gamma$-ray outbursts from flat spectrum radio quasars (FSRQs), temporarily making these objects the brightest $\gamma$-ray emitters…

High Energy Astrophysical Phenomena · Physics 2020-01-31 Manuel Meyer , Jeffrey D. Scargle , Roger D. Blandford

Blazars are known for their variability on a wide range of timescales at all wavelengths. Most studies of TeV gamma-ray blazars focus on short timescales, especially during flares. With a decade of observations from the Fermi-LAT and…

Blazars exhibit variable emission on diverse timescales. Some light curves show signs of quasiperiodic oscillations (QPOs), which may encode clues regarding the physical processes behind the emission or point to supermassive binary black…

High Energy Astrophysical Phenomena · Physics 2026-02-24 M. A. Hashad , A. Hammad , Amr A. EL-Zant

High-redshift blazars are among the most powerful objects in the Universe. The spectral and temporal properties of thirty-three distant blazars ($z>2.5$) detected in the high energy $\gamma$-ray band are investigated by analyzing the {\it…

High Energy Astrophysical Phenomena · Physics 2020-08-25 N. Sahakyan , D. Israyelyan , G. Harutyunyan , M. Khachatryan , S. Gasparyan

Aims: We aim at investigating the time-behaviour of a sample of gamma-ray blazars. We present the results from a 13 month-long optical photometry monitoring campaign of the blazars PKS 0048-097, PKS 0754+100, HB89 0827+243, PKS 0851+202,…

Variability is a prominent observational feature of blazars. The high-energy radiation mechanism of jets has always been important but still unclear. In this work, we performed a detailed analysis using Fermi-LAT data across 15 years and…

High Energy Astrophysical Phenomena · Physics 2023-12-05 Gege Wang , Hubing Xiao , Junhui Fan , Xin Zhang

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

We are leading a comprehensive multi-waveband monitoring program of 34 gamma-ray bright blazars designed to locate the emission regions of blazars from radio to gamma-ray frequencies. The "maps" are anchored by sequences of images in both…

High Energy Astrophysical Phenomena · Physics 2015-05-20 Alan Marscher , Svetlana G. Jorstad , Valeri M. Larionov , Margo F. Aller , Anne Lahteenmaki

BL Lacs are one subclass of blazars with highly energetic $\gamma$-ray emission, which is strongly boosted by a relativistic beaming effect. The latest catalogue of the 10 years of {\it Fermi}/LAT data Abdollahi et al. (2020) and the…

High Energy Astrophysical Phenomena · Physics 2021-11-18 X. H. Ye , X. T. Zeng , W. X. Yang , H. S. Huang , Y. H. Xuan , J. W. Huang , Z. Zhang , Z. Y. Pei , J. H. Yang , J. H. Fan

Blazars are a small fraction of all extragalactic sources but, unlike other objects, they are strong emitters across the entire electromagnetic spectrum. In this study we have conducted a detailed investigation of the broad-band spectral…

Cosmology and Nongalactic Astrophysics · Physics 2019-08-14 S. Cutini , D. Gasparrini , P. Giommi , M. N. Mazziotta , C. Monte

The BL Lacertae object 3C 66A was detected in a flaring state by the Fermi Large Area Telescope (LAT) and VERITAS in 2008 October. In addition to these gamma-ray observations, F-GAMMA, GASP-WEBT, PAIRITEL, MDM, ATOM, Swift, and Chandra…

BL Lacertae, the prototype of the BL Lacertae (BL Lac) category of blazars, underwent a giant $\gamma-$ray flare in April 2021. The Large Area Telescope (LAT) onboard the Fermi Gamma-ray Space Telescope (hereafter Fermi-LAT) observed a peak…

High Energy Astrophysical Phenomena · Physics 2022-12-21 Ashwani Pandey , C. S. Stalin

We investigate the spectral properties of the brightest gamma-ray flares of blazars detected by the Fermi Large Area Telescope. We search for the presence of spectral breaks and measure the spectral curvature on typical time scales of a few…

High Energy Astrophysical Phenomena · Physics 2015-06-24 Susanna Kohler , Krzysztof Nalewajko

In three years of observations since the beginning of nominal science operations in August 2008, the Large Area Telescope (LAT) on board the Fermi Gamma Ray Space Telescope has observed high-energy (>20 MeV) \gamma-ray emission from 35…

High Energy Astrophysical Phenomena · Physics 2015-06-15 LAT Collaboration

A large fraction of the AGNs detected by EGRET exhibit strong variability in many wavebands- from radio to the highest energy gamma-rays observed. The origin of the transient emission in blazars is presumably associated with relativistic…

Astrophysics · Physics 2007-05-23 Amir Levinson

A study of the gravitationally lensed blazar PKS 1830-211 was carried out using multi waveband data collected by Fermi-LAT, Swift-XRT and Swift-UVOT telescopes between MJD 58400 to MJD 58800 (9 Oct 2018 to 13 Nov 2019). Flaring states were…

High Energy Astrophysical Phenomena · Physics 2021-07-14 Jayant Abhir , Raj Prince , Jophin Joseph , Debanjan Bose , Nayantara Gupta

We present the results of the \textit{Fermi}-LAT 10-years-long light curves (LCs) modeling of selected blazars: six flat spectrum radio quasars (FSRQs) and five BL Lacertae (BL Lacs), examined in 7-, 10-, and 14-day binning. The LCs and…

High Energy Astrophysical Phenomena · Physics 2021-09-24 Mariusz Tarnopolski , Natalia Żywucka , Volodymyr Marchenko , Javier Pascual-Granado
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