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At optical/ultraviolet energies, blazars display an underlying thermal (unpolarized) contribution from the accretion disc, torus and line emitting regions, diluting the polarized emission from the jet-component. Optical polarimetry can be…

Blazars are the most luminous and variable AGNs, and thus excellent probes of accretion and emission processes close to the central engine. We focus on PKS 1510-089 ($z=0.36$), one of the brightest gamma-ray sources in the Fermi LAT…

Blazars are jetted active galactic nuclei, with the jet aligned along the observer's line of sight. Their spectral energy distributions are dominated by non-thermal emission, with an underlying thermal component at optical/ultraviolet…

High Energy Astrophysical Phenomena · Physics 2026-05-07 J. Barnard , B. van Soelen , I. P. van der Westhuizen , M. Böttcher , A. Martin-Carrillo , H. M. Schutte , S. van der Merwe , M. Zacharias

A high degree of linear polarization measured in the optical emission is an important observational feature of blazars. It provides strong evidence of the presence of relativistic particles and magnetic field ordering in the non-thermal…

High Energy Astrophysical Phenomena · Physics 2025-03-17 K K Singh , A Singh , A Tolamatti , P J Meintjes , K K Yadav

The flat spectrum radio quasar PKS 1510-089 is one of the most active blazars across the entire electromagnetic spectrum, displaying periods of flaring activity. This study explores its spectral variability over a decade. By employing the…

High Energy Astrophysical Phenomena · Physics 2024-12-25 Alfredo Amador-Portes , Vahram Chavushyan , Víctor M. Patiño-Álvarez , José Ramón-Valdés

A comprehensive study of multifrequency correlations can shed light on the nature of variation for blazars. In this work, we collect the long-term radio, optical and $\gamma$-ray light curves of PKS 1502+106. After performing the localized…

High Energy Astrophysical Phenomena · Physics 2020-01-06 Xi Shao , Yunguo Jiang , Xu Chen

Gamma-ray emitting blazars have been the targets of many recent or ongoing monitoring programmes. The resulting multi-wavelength data archives are ideal for studying the quiescent and variable behaviour of the blazar PKS 2155-304. Here,…

High Energy Astrophysical Phenomena · Physics 2017-02-15 Nikki Pekeur , Russ Taylor , Renée Kraan-Korteweg

Blazars are highly variable active galactic nuclei which emit radiation at all wavelengths from radio to gamma-rays. Polarized radiation from blazars is one key piece of evidence for synchrotron radiation at low energies and it also varies…

Blazars are highly variable, radio-loud active galactic nuclei with jets oriented at a small angle to the line of sight. The observed emission of these sources covers the whole electromagnetic spectrum from radio frequencies up to the high…

High Energy Astrophysical Phenomena · Physics 2016-04-20 Alicja Wierzcholska

We report on the variation in the optical polarization of the blazar PKS 1749+096 observed in 2008--2015. The degree of polarization (PD) tends to increase in short flares having a time-scale of a few days. The object favors a polarization…

High Energy Astrophysical Phenomena · Physics 2017-12-20 Makoto Uemura , Ryosuke Itoh , Ioannis Liodakis , Dmitry Blinov , Masanori Nakayama , Longyin Xu , Naoko Sawada , Hsiang-Yun Wu , Issei Fujishiro

Emission from blazar jets in the ultraviolet, optical, and infrared is polarized. If these low-energy photons were inverse-Compton scattered, the upscattered high-energy photons retain a fraction of the polarization. Current and future…

High Energy Astrophysical Phenomena · Physics 2015-02-03 Nachiketa Chakraborty , Vasiliki Pavlidou , Brian Fields

Radio emission in blazars -- the aligned subset of Active Galactic Nuclei (AGN) -- is produced by synchrotron electrons moving relativistically in their jet's magnetic field. Under the assumption of some degree of uniformity of the field,…

High Energy Astrophysical Phenomena · Physics 2014-04-09 I. Myserlis , E. Angelakis , L. Fuhrmann , V. Pavlidou , I. Nestoras , V. Karamanavis , A. Kraus , J. A. Zensus

Millimeter-band polarimetry offers a powerful probe of AGN jets, accessing regions less affected by opacity and Faraday rotation than at longer radio wavelengths. As part of the POLAMI program, we have conducted 14 years of 1 mm and 3 mm…

The X-ray emission from blazars has been widely investigated using several space telescopes. In this work, we explored statistical properties of the X-ray variability in the blazars S5 0716+714, OJ 287, Mkn 501 and RBS 2070 using the…

The flat spectrum radio quasar PKS 1510-089 is one of the most active blazars in $\gamma$-rays, exhibiting phases of very high activity. This study investigates its variability over a decade across a wide range of wavelengths, from radio to…

High Energy Astrophysical Phenomena · Physics 2024-10-24 Alfredo Amador-Portes , Abigail García-Pérez , Vahram Chavushyan , Victor M. Patiño-Álvarez

Polarimetric properties of blazars allow us to put constraints on the acceleration mechanisms that fuel their powerful jets. By studying the multiwavelength polarimetric behaviour of high synchrotron peaked (HSP) and low synchrotron peaked…

High Energy Astrophysical Phenomena · Physics 2025-08-21 Sara Capecchiacci , Ioannis Liodakis , Riccardo Middei , Dawoon E. Kim , Laura Di Gesu , Ivan Agudo , Beatriz Agis-Gonzalez , Axel Arbet-Engels , Dmitry Blinov , Chien-Ting Chen , Steven R. Ehlert , Ephraim Gau , Lea Heckmann , Kun Hu , Svetlana G. Jorstad , Philip Kaaret , Pouya M. Kouch , Henric Krawczynski , Elina Lindfors , Frederic Marin , Alan P. Marscher , Ioannis Myserlis , Stephen L. O'Dell , Luigi Pacciani , David Paneque , Matteo Perri , Simonetta Puccetti , M. Lynne Saade , Fabrizio Tavecchio , Allyn F. Tennant , Efthalia Traianou , Martin C. Weisskopf , Kinwah Wu , Francisco Jose Aceituno , Giacomo Bonnoli , Victor Casanova , Gabriel Emery , Juan Escudero , Daniel Morcuende , Jorge Otero-Santos , Alfredo Sota , Vilppu Piirola , George A. Borman , Evgenia N. Kopatskaya , Elena G. Larionova , Daria A. Morozova , Ekaterina V. Shishkina , Sergey S. Savchenko , Andrey A. Vasilyev , Tatiana S. Grishina , Ivan S. Troitskiy , Alexey V. Zhovtan , Callum McCall , Helen E. Jermak , Iain A. Steele , Rumen Bachev , Anton Strigachev , Ryo Imazawa , Mahito Sasada , Yasushi Fukazawa , Koji S. Kawabata , Makoto Uemura , Tsunefumi Mizuno , Tatsuya Nakaoka , Sumie Tochihara , Takahiro Akai , Hiroshi Akitaya , Andrei V. Berdyugin , Masato Kagitani , Vadim Kravtsov , Juri Poutanen , Takeshi Sakanoi , Diego Alvarez-Ortega , Carolina Casadio , Sincheol Kang , Sang-Sung Lee , Sanghyun Kim , Whee Yeon Cheong , Hyeon-Woo Jeong , Chanwoo Song , Shan Li , Myeong-Seok Nam , Mark Gurwell , Garrett Keating , Ramprasad Rao , Emmanouil Angelakis , Alexander Kraus , Petra Benke , Lena Debbrecht , Julia Eich , Florian Eppel , Andrea Gokus , Steven Hammerich , Jonas Hessdorfer , Matthias Kadler , Dana Kirchner , Georgios Filippos Paraschos , Florian Rosch , Wladislaw Schulga

Contemporaneous multiwavelength observations with H.E.S.S., SALT, Fermi-LAT, Swift, and ATOM show that the blazar PKS 1510-089 suffered a significant decrease in its optical flux, degree of optical polarization and high-energy gamma-ray (E…

High Energy Astrophysical Phenomena · Physics 2023-11-03 H. M. Schutte , M. Zacharias , M. Böttcher , J. Barnard , D. A. H. Buckley , J. Cooper , D. Groenewald

We present multiwavelength observations of the ultraluminous blazar-type radio loud quasar PKS 0528+134 in quiescence during the period July to December 2009. Significant flux variability on a time scale of several hours was found in the…

High Energy Astrophysical Phenomena · Physics 2015-05-27 N. I. Palma , M. Boettcher

Context. Blazars are a subset of active galactic nuclei (AGN) with jets that are oriented along our line of sight. Variability and spectral energy distribution (SED) studies are crucial tools for understanding the physical processes…

We present multi-epoch optical spectroscopy of seven southern Fermi-monitored blazars from 2008 - 2013 using the Small and Medium Aperture Research Telescope System (SMARTS), with supplemental spectroscopy and polarization data from the…

High Energy Astrophysical Phenomena · Physics 2015-11-11 Jedidah C. Isler , C. M. Urry , C. Bailyn , P. S. Smith , P. Coppi , M. Brady , E. Macpherson , I. Hasan , M. Buxton
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