Rapid X-ray Variability in Mkn 421 during a Multiwavelength Campaign
Abstract
The study of short-term variability properties in AGN jets has the potential to shed light on their particle acceleration and emission mechanisms. We report results from a four-day coordinated multi-wavelength campaign on the highly-peaked blazar (HBL) Mkn 421 in 2019 January. We obtained X-ray data from AstroSAT, BVRI photometry with the Whole Earth Blazar Telescope (WEBT), and TeV data from FACT to explore short-term multi-wavelength variability in this HBL. The X-ray continuum is rapidly variable on time-scales of tens of ks. Fractional variability amplitude increases with energy across the synchrotron hump, consistent with previous studies; we interpret this observation in the context of a model with multiple cells whose emission spectra contain cutoffs that follow a power-law distribution. We also performed time-averaged and time-resolved (time-scales of 6 ks) spectral fits; a broken power-law model fits all spectra well; time-resolved spectral fitting reveals the usual hardening when brightening behaviour. Intra-X-ray cross correlations yield evidence for the 0.6-0.8 keV band to likely lead the other bands by an average of 4.6 +- 2.6 ks, but only during the first half of the observation. The source displayed minimal night-to-night variability at all wavebands thus precluding significant interband correlations during our campaign. The broadband SED is modeled well with a standard one-zone leptonic model, yielding jet parameters consistent with those obtained from previous SEDs of this source.
Cite
@article{arxiv.2206.03874,
title = {Rapid X-ray Variability in Mkn 421 during a Multiwavelength Campaign},
author = {Alex G. Markowitz and Krzysztof Nalewajko and Gopal Bhatta and Gulab C. Dewangan and Sunil Chandra and Daniela Dorner and Bernd Schleicher and Urszula Pajdosz-Smierciak and Lukasz Stawarz and Staszek Zola and Michal Ostrowski and Daniele Carosati and Saikruba Krishnan and Rumen Bachev and Erika Benitez and Kosmas Gazeas and David Hiriart and Shao-Ming Hu and Valeri Larionov and Alessandro Marchini and Katsura Matsumoto and A. A. Nikiforova and Tapio Pursimo and Claudia M. Raiteri and Daniel E. Reichart and Diego Rodriguez and Evgeni Semkov and Anton Strigachev and Yuki Sugiura and Massimo Villata and James R. Webb and Axel Arbet-Engels and Dominik Baack and Matteo Balbo and Adrian Biland and Thomas Bretz and Jens Buss and Laura Eisenberger and Dominik Elsaesser and Dorothee Hildebrand and Roman Iotov and Adelina Kalenski and Karl Mannheim and Alison Mitchell and Dominik Neise and Maximilian Noethe and Aleksander Paravac and Wolfgang Rhode and Vitalii Sliusar and Roland Walter},
journal= {arXiv preprint arXiv:2206.03874},
year = {2022}
}
Comments
This article has been accepted for publication in The Monthly Notices of the Royal Astronomical Society (2022), and is published in Volume 513, Issue 2, pp.1662-1679. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved. 19 pages; 12 figures