Related papers: Temporal variability of polarization in blazars
Mildly relativistic, oblique shocks are frequently invoked as possible sites of relativistic particle acceleration and production of strongly variable, polarized multi-wavelength emission from relativistic jet sources such as blazars, via…
We report the measurement of X-ray polarization in the high synchrotron peaked blazar 1ES 1959+650. Of the four epochsof observations from the {\it Imaging X-ray Polarimetry Explorer}, we detected polarization in the 2$-$8 keV band on two…
We collected the archival data of blazar OJ~287 from heterogeneous very long baseline interferometry (VLBI) monitoring programs at 2.3 GHz, 8.6 GHz, 15 GHz and 43 GHz. The data reduction and observable extraction of those multi-band…
The lower energy peak of the spectral energy distribution of blazars has commonly been ascribed to synchrotron radiation from relativistic particles in the jets. Despite the consensus regarding jet emission processes, the particle…
Synchrotron radiation is commonly observed in connection with shocks of different velocities, ranging from relativistic shocks associated with active galactic nuclei, gamma-ray bursts or microquasars to weakly- or non-relativistic flows as…
This report presents the results of optical polarimetric observations carried out with 6-m and 1-m telescopes at SAO RAS. The study of the blazar S5 0716+714 radiation showed the presence of a period of the variability of brightness and…
Observations of linear polarization in the 2-8 keV energy range with the Imaging X-ray Polarimetry Explorer (IXPE) explore the magnetic field geometry and dynamics of the regions generating non-thermal radiation in relativistic jets of…
We present ~2000 polarimetric and ~3000 photometric observations of 15 gamma-ray bright blazars over a period of 936 days (11/10/2008 - 26/10/2012) using data from the Tuorla blazar monitoring program (KVA DIPOL) and Liverpool Telescope…
Variability can be the pathway to understanding the physical processes in astrophysical jets, however, the high-cadence observations required to test particle acceleration models are still missing. Here we report on the first attempt to…
Among active galactic nuclei, blazars show extreme variability properties. We here investigate the case of the BL Lac object S4 0954+65 with data acquired in 2019-2020 by the Transiting Exoplanet Survey Satellite (TESS) and by the Whole…
We report on long-term multi-wavelength monitoring of blazar Mrk 421 by the GASP-WEBT collaboration and Steward Observatory, and by the Swift and Fermi satellites. We study the source behaviour in the period 2007-2015, characterized by…
We present an automated pipeline for the detection of EVPA rotations in blazars, integrating correction of the 180$^\circ$ ambiguity, Bayesian Blocks segmentation, and statistical validation. Applied to RoboPol monitoring data, the method…
Multi-wavelength light curves of bright gamma-ray blazars (e.g., 3C 454.3) reveal strong correlations across wavebands, yet striking dissimilarities in the details. This conundrum can be explained if the variable flux and polarization…
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,…
We used 15 GHz multi-epoch Very Long Baseline Array (VLBA) polarization sensitive observations of 484 sources within a time interval 1996--2016 from the MOJAVE program, and also from the NRAO data archive. We have analyzed the linear…
The knowledge of the structure of the magnetic field inside a blazar jet, as deduced from polarization observations at radio to optical wavelengths, is closely related to the formation and propagation of relativistic jets that result from…
The kinetic energy of bulk relativistic plasma ejected from the central engine of blazars is converted into nonthermal particle energy in the comoving frame through a process of sweeping up material from the surrounding medium. The…
With their emission mainly coming from a relativistic jet pointing towards us, blazars are fundamental sources to study extragalactic jets and their central engines, consisting of supermassive black holes (SMBHs) fed by accretion discs.…
X-ray and MeV polarization can be powerful diagnostics for leptonic and hadronic blazar models. Previous predictions are mostly based on a one-zone framework. However, recent IXPE observations of Mrk~421 and 501 strongly favor a multi-zone…
The bright X-ray selected BL Lacertae object PKS 2155-304 has been the target of two intense multiwavelength campaigns, in November 1991 and in May 1994. Although the spectral energy distributions at both epochs were quite similar, the…