CTA 102 in exceptionally high state during 2016-2017

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dc.contributor.author Kaur, Navpreet
dc.contributor.author Baliyan, Kiran S.
dc.date.accessioned 2018-10-04T12:52:44Z
dc.date.available 2018-10-04T12:52:44Z
dc.date.issued 2018-09
dc.identifier.citation Kaur, Navpreet and Baliyan, Kiran S., "CTA 102 in exceptionally high state during 2016-2017", Astronomy & Astrophysics, DOI: 10.1051/0004-6361/201731953, vol. 617, Sep. 2018. en_US
dc.identifier.issn 0004-6361
dc.identifier.issn 1432-0746
dc.identifier.uri https://doi.org/10.1051/0004-6361/201731953
dc.identifier.uri https://repository.iitgn.ac.in/handle/123456789/3932
dc.description.abstract Blazars in outburst provide a unique opportunity to study their spectral behavior, correlated variations at different frequencies, and jet structure. An unprecedented flaring activity in FSRQ CTA 102, occuring from 2016 November to 2017 January, is used here for a detailed study to understand flaring mechanisms at short and long timescales, spectral behavior in different energy regimes, and to estimate sizes and location of the high-energy emitting region in the jet. Multiwavelength (MW) data for CTA 102 during its outburst period, were obtained from Fermi-LAT, Swift-XRT/UVOT, Steward Observatory, Mt Abu Infrared Observatory, and OVRO. These were analyzed to construct MW light curves, extract the spectral information, and to perform the correlated variability studies. Our study shows that CTA 102 attained the highest ever flux levels across the electromagnetic spectrum (EMS) while flaring and otherwise, with rapid and prolonged activities at all the frequencies. A number of short-term (three to eight days) and long-term (more than a month) variability events are noticed across the EMS. We infer a redder when brighter trend in faint state and a bluer when brighter trend during a few optical flares. Based on the flux doubling timescale, the size of γ-ray emitting region is estimated as ≈8.76 × 1015 cm, located at a distance of about 5.58 × 1016 cm from the central engine. CTA 102 was in extremely bright phase during 2016–2017, possibly due to, successive high energy particle injections into the jet, creating shocks traveling down the jet which lead to the overall flux enhancement across the EMS. Alternatively, a decreasing viewing angle could also lead to such flux enhancement. The study reveals correlated variations in all the energy bands, with lags within time bins, indicating co-spatial origin of the emissions. During the flaring event, a bluer-when-brighter color in the optical and harder when brighter trend in the X-ray and γ-ray spectra are noticed. During some flares softer γ-ray spectra are observed.
dc.description.statementofresponsibility by Navpreet Kaur and Kiran S. Baliyan
dc.language.iso en en_US
dc.publisher EDP Sciences for European Southern Observatory en_US
dc.subject galaxies: active en_US
dc.subject galaxies: jets en_US
dc.subject gamma rays: galaxies en_US
dc.subject radiation mechanisms: non-thermal en_US
dc.subject techniques: photometric en_US
dc.subject methods: observational en_US
dc.title CTA 102 in exceptionally high state during 2016-2017 en_US
dc.type Article en_US
dc.relation.journal Astronomy & Astrophysics

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