Related papers: Catching profound optical flares in blazars
Multiwavelength monitoring of the blazar 3C 279 observed a very bright, 12-hour, orphan gamma-ray flare on 20 Dec 2013 with a uniquely hard Fermi-LAT spectrum and high Compton dominance. We work with a one-zone, leptonic model with both…
In 2021 BL Lacertae underwent an extraordinary activity phase, which was intensively followed by the Whole Earth Blazar Telescope (WEBT) Collaboration. We present the WEBT optical data in the BVRI bands acquired at 36 observatories around…
Detection of periodicity in the broad-band non-thermal emission of blazars has so far been proven to be elusive. However, there are a number of scenarios which could lead to quasi-periodic variations in blazar light curves. For example,…
Over the course of three hours on 27 December 2008 we obtained optical (R-band) observations of the blazar S5 0716+714 at a very fast cadence of 10 s. Using several different techniques we find fluctuations with an approximately 15-minute…
We have measured multi-band optical flux and colour variations for a sample of 12 low energy peaked blazars on short, day-to-month, timescales. Our sample contains six BL Lacertae objects and six flat spectrum radio quasars. These…
The extreme TeV blazar 1ES 0229+200 is a high-frequency-peaked BL Lacertae object. It has not shown intraday variability in extensive optical and X-ray observations. Nor has it shown any significant variability on any measurable timescale…
We carried out a high time-resolution, multicolour optical observing campaign for eight $\gamma$-ray detected blazars during 2010-2020. We analyze flux variations, correlations between magnitudes and colours on different timescales.…
BL Lacertae had undergone a series of historical high flux activity over a year, from August 2020 in the optical to VHE $\gamma$-rays. In this paper, we report on optical flux and spectral variability of the first historical maxima outburst…
Recently, blazar 4C +27.50 was found to be flaring in gamma-rays since its detection with Fermi-LAT in 2008. For the first time, a dedicated temporal and spectral study of the blazar 4C +27.50 has been performed in this work to understand…
We report the detection of high polarization in the first detailed optical linear polarization measurements on the BL Lac object CGRaBS J0211+1051, which flared in $\gamma$-rays on 2011 January 23 as reported by Fermi. The observations were…
On 2015 June 16, Fermi-LAT observed a giant outburst from the flat spectrum radio quasar 3C 279 with a peak $>100$ MeV flux of $\sim3.6\times10^{-5}\;{\rm photons}\;{\rm cm}^{-2}\;{\rm s}^{-1}$ averaged over orbital period intervals. It is…
The search for periodic signals from blazars has become an actively pursued field of research in recent years. This is because periodic signals bring us information about the processes occurring near the innermost regions of blazars, which…
The very short and bright flare of 3C 279 detected with {\it Fermi}-LAT in 2013 December is tested by a model with stochastic electron acceleration by turbulences. Our time-dependent simulation shows that the very hard spectrum and…
A multiwavelength temporal and spectral analysis of flares of 3C 279 during November 2017--July 2018 are presented in this work. Three bright gamma-ray flares were observed simultaneously in X-ray and Optical/UV along with a prolonged…
We report the AGILE detection and the results of the multifrequency follow-up observations of a bright $\gamma$-ray flare of the blazar 3C 279 in June 2015. We use AGILE-GRID and Fermi-LAT $\gamma$-ray data, together with Swift-XRT,…
An exceptional $\gamma$-ray outburst from 3C 279 is detected by {\it Fermi}-Large Area Telescope (LAT) in 2015 June. In the energy range of 0.1$-$300 GeV, the highest flux measured is (39.1$\pm$2.5) $\times$ 10$^{-6}$ \phflux, which is the…
Blazars can be detected from very large distances due to their high luminosity. However, the detection of $\gamma$-ray emission of blazars beyond $z=3$ has only been confirmed for a small number of sources. Such observations probe the…
The blazar 3C 279 exhibited a giant $\gamma$-ray outburst in 2013 December and 2014 April. Apart from the very fast $\gamma$-ray flux variability, the spectral nature of the flares were also found to vary significantly between these two…
About twenty years of radio observations in five bands (from 4.8 to 37 GHz) of the BL Lac object GC 0109+224 (S2 0109+22, RGB J0112+227), are presented and analysed together with the optical data. Over the past ten years this blazar has…
We present the results of a broadband radio-to-GeV observing campaign organized to get a better understanding of the radiation processes responsible for the $\gamma$-ray flares observed in 3C 279. The total intensity and polarization…