X-Ray Observations of 1ES 1959+650 in Its High-activity State in 2016-2017 with AstroSat and Swift
Abstract
We present a comprehensive multifrequency study of the high-frequency-peaked BL Lac object 1ES 1959+650 using data from various facilities during the period 2016-2017, including X-ray data from AstroSat and Swift during the historically high X-ray flux state of the source observed until 2021 February. The unprecedented quality of X-ray data from high-cadence monitoring with AstroSat during 2016-2017 enables us to establish a detailed description of X-ray flares in 1ES 1959+650. The synchrotron peak shifts significantly between different flux states, in a manner consistent with a geometric (changing Doppler factor) interpretation. A time-dependent leptonic diffusive shock acceleration and radiation transfer model is used to reproduce the spectral energy distributions and X-ray light curves, to provide insight into the particle acceleration during the major activity periods observed in 2016 and 2017. The extensive data of Swift-XRT from 2015 December to 2021 February (exp. = 411.3 ks) reveals a positive correlation between flux and peak position.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- September 2021
- DOI:
- 10.3847/1538-4357/ac01d1
- arXiv:
- arXiv:2105.08119
- Bibcode:
- 2021ApJ...918...67C
- Keywords:
-
- Blazars;
- Active galactic nuclei;
- black hole physics;
- Jets;
- High energy astrophysics;
- 164;
- 16;
- 159;
- 870;
- 739;
- Astrophysics - High Energy Astrophysical Phenomena
- E-Print:
- 25 pages, 10 figures, 10 tables [Accepted by the Astrophysical Journal]