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|Title:||Strong X-ray flaring activity of the BL Lacertae source OJ 287 in 2016 October-2017 April||Authors:||Kapanadze, B.
|Issue Date:||2018||Journal:||MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY||Number:||480||Issue:||1||First Page:||407||Abstract:||We present the results of a detailed X-ray timing and spectral analysis of the BL Lacertae source OJ 287 with X-ray telescope (XRT) onboard Neil Gehrels Swift Observatory, focused on the period of its significantly enhanced X-ray flaring activity during 2016 October-2017 April. In this epoch, the 0.3-10 keV count rate from the XRT observations showed an increase by a factor of ∼10 compared to the quiescent level observed in 2016 April-May, and the mean X-ray flux was a factor of 4.5 higher than in previous years. The source underwent high X-ray flaring activity on weekly time-scales and showed 32 instances of 0.3-10 keV intraday variability (detected within the exposures shorter than 1 ks in the majority of cases) with fractional variability amplitudes of 7-60 per cent. Most of the 0.3-10 keV spectra spectra fitted well with a simple power law, yielding a wide range of the 0.3-10 keV photon index Γ = 1.90-2.90. We found 29 spectra showing an upward curvature due to the significant contribution made by the X-ray photons of inverse Compton origin. The spectral variability of OJ 287 was characterized by the dominance of a `softer-when-brighter' spectral trend, explained by the emergence of a new soft component during X-ray flares. Similar to X-rays, the source underwent a strong outburst by factors of 4.6-6.5 in the optical-ultraviolet energy range which showed a positive correlation with the X-ray emission, indicating its origin to be related to the same electron population, predominantly via the synchrotron mechanism.||URI:||http://hdl.handle.net/20.500.12386/28400||URL:||https://academic.oup.com/mnras/article/480/1/407/5050074||ISSN:||0035-8711||DOI:||10.1093/mnras/sty1803||Bibcode ADS:||2018MNRAS.480..407K||Fulltext:||open|
|Appears in Collections:||1.01 Articoli in rivista|
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checked on Jan 17, 2021
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