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The Fermi Large Area Telescope (Fermi LAT) provides long term systematic monitoring observations of the gamma-ray emission from blazars. The variability properties and the correlation with other wavelength bands are important clues for the…

High Energy Astrophysical Phenomena · Physics 2019-08-13 Stefan Larsson

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 present cross-correlation studies of gamma-ray (0.1-300 GeV), X-ray (0.2-10 keV) and optical (R-band) variability of a sample of 26 blazars during 2008-2016. The light curves are from Fermi-LAT, Swift-XRT, and the Yale-SMARTS blazar…

High Energy Astrophysical Phenomena · Physics 2020-04-08 Anwesh Majumder , Kaustav Mitra , Ritaban Chatterjee , C. M. Urry , C. D. Bailyn , Prantik Nandi

We present the results of our follow-up observation program of gamma-ray sources detected by the Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope. 26 blazars and 39 sources unidentified at other wavelengths were…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-11 Mai Fujiwara , Yoshiki Matsuoka , Nobuyuki Ienaka

We present long term optical and near infrared flux variability analysis of 37 blazars detected in the $\gamma$-ray band by the {\it Fermi Gamma-Ray Space Telescope}. Among them, 30 are flat spectrum radio quasars (FSRQs) and 7 are BL Lac…

High Energy Astrophysical Phenomena · Physics 2020-08-28 P. Z. Safna , C. S. Stalin , Suvendu Rakshit , Blesson Mathew

Blazars present highly variable $\gamma$-ray emission. This variability, which can range from a few minutes to several years, is also observed at other wavelengths across the entire electromagnetic spectrum. We make use of the first 12…

High Energy Astrophysical Phenomena · Physics 2024-03-05 P. Peñil , J. Otero-Santos , M. Ajello , S. Buson , A. Domínguez , L. Marcotulli , N. Torres-Albà , J. Becerra González , J. A. Acosta-Pulido

Blazars are known for their energetic multiwavelength flares from radio wavelengths to high-energy $\gamma$-rays. In this work, we study radio, optical, and $\gamma$-ray light curves of 145 bright blazars spanning up to 8~yr, to probe the…

High Energy Astrophysical Phenomena · Physics 2018-08-20 I. Liodakis , R. W. Romani , A. V. Filippenko , S. Kiehlmann , W. Max-Moerbeck , A. C. S. Readhead , W. Zheng

We perform correlation and periodicity search analyses on long-term multi-band light curves of the FSRQ 1510-089 observed by the space-based Fermi--Large Area Telescope in gamma-rays, the SMARTS and Steward Observatory telescopes in optical…

Using blazar light curves from the optical All-Sky Automated Survey for Supernovae (ASAS-SN) and the $\gamma$-ray \textit{Fermi}-LAT telescope, we performed the most extensive statistical correlation study between both bands, using a sample…

High Energy Astrophysical Phenomena · Physics 2023-01-18 T. de Jaeger , B. J. Shappee , C. S. Kochanek , J. T. Hinkle , S. Garrappa , I. Liodakis , A. Franckowiak , K. Z. Stanek , J. F. Beacom , J. L. Prieto

Blazars are a small fraction of all extragalactic sources but, unlike other objects, they are strong emitters across the entire electromagnetic spectrum. Recent data in the microwave region of the electromagnetic spectrum have become…

Cosmology and Nongalactic Astrophysics · Physics 2013-12-24 D. Gasparrini , E. Cavazzuti , P. Giommi , C. Pittori , S. Colafrancesco , Fermi-LAT collaboration

In order to determine the location of the gamma-ray emission site in blazars, we investigate the time-domain relationship between their radio and gamma-ray emission. Light-curves for the brightest detected blazars from the first 3 years of…

Blazars display variable emission across the entire electromagnetic spectrum, with timescales that can range from a few minutes to several years. Our recent work has shown that a sample of five blazars exhibit hints of periodicity with a…

High Energy Astrophysical Phenomena · Physics 2023-10-20 P. Peñil , J. R. Westernacher-Schneider , M. Ajello , A. Domínguez , S. Buson , J. Otero-Santos , L. Marcotulli , N. Torres-Albà , J. Zrake

Flaring activity from the jets of active galactic nuclei has been studied for several decades, closely related to the loading and evolution of the jet. In this work, we focus on the sub-hundred parsec jet region, well traced by non-thermal…

High Energy Astrophysical Phenomena · Physics 2026-04-07 Alina Kochocki , Emma Kun , Sam Hori

We present multi-epoch observations from the Submillimeter Array (SMA) for a sample of 171 bright blazars, 43 of which were detected by Fermi during the first three months of observations. We explore the correlation between their gamma-ray…

High Energy Astrophysical Phenomena · Physics 2010-01-07 Allison L. Strom , Aneta Siemiginowska , Mark A. Gurwell , Brandon C. Kelly

Blazars are a subclass of active galactic nuclei (AGN) having relativistic jets aligned within a few degrees of our line-of-sight and form the majority of the AGN detected in the TeV regime. The Fermi-Large Area Telescope (LAT) is a…

High Energy Astrophysical Phenomena · Physics 2023-07-04 Atreya Acharyya , Alberto C. Sadun

The Fermi/LAT telescope is an efficient blazar-detector in the MeV/GeV range. More than 1100 (900) blazars detected above 100 MeV (10 GeV) are clearly associated to BL Lacertae or Flat Spectrum Radio Quasar objects in the Fermi/LAT 3FGL…

High Energy Astrophysical Phenomena · Physics 2017-10-02 Julien Lefaucheur , Catherine Boisson , Paolo Goldoni , Santiago Pita

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

Using data from the Fermi Large Area Telescope (LAT), we report the first clear gamma-ray measurement of a delay between flares from the gravitationally lensed images of a blazar. The delay was detected in B0218+357, a known double-image…

Blazars are known to exhibit variability across a broad range of timescales. This behavior can include periodicity in their $\gamma$-ray emission, whose clear detection remains an ongoing challenge, partly due to the inherent stochasticity…

High Energy Astrophysical Phenomena · Physics 2025-07-08 P. Peñil , M. Ajello , S. Buson , A. Domínguez , J. R. Westernacher-Schneider , A. Rico , S. Adhikari , J. Zrake

A majority of blazars exhibit variable emission across the entire electromagnetic spectrum, observed over various time scales. In particular, discernible periodic patterns are detected in the $\gamma$-ray light curves of a few blazars, such…

High Energy Astrophysical Phenomena · Physics 2025-06-18 Alba Rico , A. Domínguez , P. Peñil , M. Ajello , S. Buson , S. Adhikari , M. Movahedifar
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