Title:	Optical flux and spectral characterization of the blazar PG 1553 + 113 based on the past 15 years of data
Authors:	Agarwal, Aditi Mihov, B. Andruchow, I. Cellone, Sergio A. Anupama, G.C. Agrawal, V. Zola, S. Özdönmez, Aykut Ege, Ergün
Keywords:	Active galaxies BL Lacertae objects
Issue Date:	15-Feb-2022
Publisher:	Springer for Indian Academy of Sciences
Citation:	Journal of Astrophysics and Astronomy, 2022, Vol. 43, Article No. - 9
Abstract:	We study flux and spectral variability of the high energy peaked TeV blazar PG 1553 + 113 on diverse timescales using the data collected from 2005 to 2019 which also includes the intensive intra-night monitoring of the target. Additionally, we recorded the brightest flare of the blazar PG 1553 + 113 during April 2019 when the source attained an R-band magnitude of 13.2. Analyzing the spectral evolution of the source during the flare gave a clockwise spectral hysteresis loop and a time lag with V-band variations leading to the R-band ones. Various statistical tests, fitting procedures and cross-correlation techniques are applied to search for periodicity and examine the color-magnitude relationship. We find a median period of (2.21 ± 0.04) years along with the secondary period of about 210 days. Finally, we briefly discuss various physical mechanisms which are capable of explaining our findings.
Description:	Open Access from Indian Academy of Sciences
URI:	http://hdl.handle.net/2289/7910
ISSN:	0250-6335 0973-7758 (Online)
Alternative Location:	https://ui.adsabs.harvard.edu/abs/2022JApA...43....9A/abstract https://doi.org/10.1007/s12036-021-09793-5
Copyright:	2022 Indian Academy of Sciences
Appears in Collections:	Research Papers (A&A)

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