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http://hdl.handle.net/20.500.12386/28403
Title: | The second strong X-ray flare and multifrequency variability of 1ES 1959+650 in 2016 January-August | Authors: | Kapanadze, B. Dorner, D. VERCELLONE, STEFANO ROMANO, Patrizia Hughes, P. Aller, M. Aller, H. Reynolds, M. Kapanadze, S. Tabagari, L. |
Issue Date: | 2018 | Journal: | MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY | Number: | 473 | Issue: | 2 | First Page: | 2542 | Abstract: | The X-ray variability of the BL Lacertae source 1ES 1959+650 was studied intensively with X-ray telescope (XRT) onboard Swift during 2016 January-August. In this paper, we present the results obtained during this campaign. A long-term high X-ray state was superimposed by shorter-term flares by a factor of 1.9-4.7. We found 35 instances of intra-day variability which showed very fast flux changes by 14-21 per cent occurring within 1 ks and a decline by a factor of 2.3 in 17.2 ks. Similarly to the previous years, this period sometimes was characterized by a lack of correlated X-ray and TeV variability, indicating that the high-energy emission in 1ES 1959+650 was generated in the emission region more complex than a single zone. The source showed a significant X-ray - high-energy flux correlation, while the former was not correlated with the optical-UV fluxes. The best fits of the 0.3-10 keV spectra were mainly obtained using the log-parabola model. Strong spectral variability was detected, shifting the peak of the spectral energy distribution by more than 10 keV that happens rarely in blazars. During some strong short-term flares, the photon index at 1 keV frequently became harder than 1.70, and the spectral evolution was characterized by a harder-when-brighter behaviour. | URI: | http://hdl.handle.net/20.500.12386/28403 | URL: | https://academic.oup.com/mnras/article/473/2/2542/4259577 | ISSN: | 0035-8711 | DOI: | 10.1093/mnras/stx2492 | Bibcode ADS: | 2018MNRAS.473.2542K | Fulltext: | open |
Appears in Collections: | 1.01 Articoli in rivista |
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Kapanadze_2018_MNRAS_473_2542.pdf | PDF editoriale | 3.34 MB | Adobe PDF | View/Open |
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