V. M. Larionov
Articles written in Journal of Astrophysics and Astronomy
Volume 32 Issue 1-2 March 2011 pp 239-242 Part 6. Combined Multi-Waveband Observations
We perform monthly monitoring of the quasar 1633+382 (4C+38.41) within a sample of 𝛾-ray blazars with the VLBA at 43 GHz along with optical photometric and polarimetric observations. We construct the 𝛾-ray light curve of 1633+382 using data obtained by the Fermi LAT. We find that a high 𝛾-ray state of the quasar starting in 2009 September is simultaneous with an increase of the flux in the mm-wave VLBI core. We resolve a superluminal feature on the VLBA images that appears to be responsible for the mm-wave flux increase. We find a strong correlation between optical and 𝛾-ray light curves with a delay of 𝛾-ray variations of 5 ± 3 days, as well as a strong correlation between optical flux and degree of polarization during the high 𝛾-ray state. Comparison between the optical polarization position angle and that in the VLBI core supports the idea that in the quasar 1633+382 a high 𝛾-ray state is connected with processes originating near the mm-VLBI core.
Volume 42 All articles Published: 17 July 2021 Article ID 0080 SCIENCE RESULTS
RITABAN CHATTERJEE SUSMITA DAS ARCHISHMAN KHASNOVIS RITESH GHOSH NEERAJ KUMARI SACHINDRA NAIK V. M. LARIONOV T. S. GRISHINA E. N. KOPATSKAYA E. G. LARIONOVA A. A. NIKIFOROVA D. A. MOROZOV S. S. SAVCHENKO YU. V. TROITSKAYA I. S. TROITSKY A. A. VASILYEV
We study the multi-wavelength variability of the blazar Mrk 421 at minutes to days timescales using simultaneous data at c-rays from Fermi, 0.7–20 keV energies from AstroSat, and optical and near infrared (NIR) wavelengths from ground based observatories. We compute the shortest variability timescalesat all of the above wave bands and find its value to be $\sim$1.1 ks at the hard X-ray energies and increasingly longer at soft X-rays, optical and NIR wavelengths as well as at the GeV energies. We estimate the value ofthe magnetic field to be 0.5 Gauss and the maximum Lorentz factor of the emitting electrons $\sim 1.6 \times 10^5$ assuming that synchrotron radiation cooling drives the shortest variability timescale. Blazars vary at a largerange of timescales often from minutes to years. These results, as obtained here from the very short end of the range of variability timescales of blazars, are a confirmation of the leptonic scenario and in particular the synchrotron origin of the X-ray emission from Mrk 421 by relativistic electrons of Lorentz factor as high as $10^5$. This particular mode of confirmation has been possible using minutes to days timescale variability data obtained from AstroSat and simultaneous multi-wavelength observations.
Volume 42, 2021
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