Related papers: X-ray variability patterns in blazars
The common observations of multiple radio VLBI stationary knots in high-frequency-peaked BL Lacs (HBLs) can be interpreted as multiple recollimation shocks accelerating particles along jets. This approach can resolve the so-called "bulk…
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,…
In this work, we analyzed multi-wavelength data of the BL Lac object S5 0716+714 to investigate its emission mechanisms during a flaring state observed in early 2015. We examined the temporal behavior and broadband spectral energy…
Very fast variability on scales of minutes is regularly observed in Blazars. The assumption that these flares are emerging from the dominant emission zone of the very high energy (VHE) radiation within the jet challenges current…
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…
We select a sample of 10 radio-quiet quasars with confirmed intranight optical variability and with available X-ray data. We compare the variability properties and the broad band spectral constraints to the predictions of intranight…
We present a model of blazar variability that can both reproduce smooth large polarization angle swings, and at the same time allow for the seemingly random behaviour of synchrotron fluxes, polarization fraction and, occasionally, $\pi$/2…
We present the results of our study of cross-correlations between long-term multi-band observations of the radio variability of the blazar 3C 279. More than a decade (2008-2022) of radio data were collected at seven different frequencies…
J1415+1320 is a well-studied blazar that exhibits strong flux density variability at a wide range of radio frequencies (2.4 $-$ 230~GHz). In this letter, we present a variability study of this source at 327~MHz using the data obtained with…
This paper reports X-ray spectral observations of a relatively nearby z = 0.048 BL Lacertae (BL Lac) object 1ES1959+650, which is a potential TeV emitter. The observations include 31 short pointings made by the Unconventional Stellar Aspect…
We developed a multi-region radiation model for the evolution of flux and spectral index with time. In this model, each perturbation component in the jet produces an independent flare. The model can be used to study the decomposition of…
Blazar flare data show energy-dependent lags and correlated variability between optical/X-ray and GeV-TeV energies, and follow characteristic trajectories when plotted in the spectral-index/flux plane. This behavior is qualitatively…
Linear time series analysis, mainly the Fourier transform based methods, has been quite successful in extracting information contained in the ever-modulating light curves (Lcs) of active galactic nuclei, and thereby contribute in…
Fermi-LAT observations provide continuous and regularly-sampled measurements of gamma-ray photon flux for hundreds of blazars. Many of these light curves, spanning almost 15 years, have been thoroughly examined for periodicity in multiple…
The synchrotron hump of the high energy peaked blazars generally lies in the 0.1-10 keV range and such sources show extreme flux and spectral variability in X-ray bands. Various spectral studies showed that the X-ray spectra of high energy…
We analyze X-ray light curves of the blazars Mrk 421, PKS 2155-304, and 3C 273 using observations by the Soft X-ray Telescope on board AstroSat and archival XMM-Newton data. We use light curves of length 30-90 ks each from 3-4 epochs for…
Blazars are characterized by large amplitude and fast variability, indicating that the electron distribution is rapidly changing, often on time scales shorter than the light crossing time. The emitting region is sufficiently compact to let…
Critical progress in our understanding of high energy emission from AGN has been determined in the last 10 years by X-ray monitoring campaigns with many space missions, notably ROSAT, ASCA, RXTE, BeppoSAX, and XMM, often in conjunction with…
We report on the presence of very rapid hard X-ray variability in the $\gamma$-ray binary LS I +61 303. The results were obtained by analysing NuSTAR data, which show two achromatic strong flares on ks time-scales before apastron. The…
High synchrotron energy peaked blazar 1ES 1959+650 is studied with Swift and XMM-Newton satellite in total 127 observations during the period June 2018-December 2020. We extensively studied its flux and spectral variability on intra-day and…