Multiwavelength study of different flaring and low-activity states of blazar 4C+21.35

Abstract

Blazars, a class of active galactic nuclei emit over the entire accessible electromagnetic spectrum and modelling of their broadband spectral energy distribution (SED) is the key to constrain the underlying emission mechanisms. Here we report the results on the one zone leptonic emission modelling carried out on the blazar 4C +21.35 using multi-wavelength data spanning over the period 2008 - 2018. Broadband SED modelling using γ-ray data from Fermi-Large Area Telescope, X-ray data from Swift-XRT, AstroSat, UV-Optical data from Swift-UVOT, AstroSat, and Catalina Real-Time Transient Survey was carried out at seven different epochs, including three γ-ray flaring episodes and four quiescent periods (three long-term averaged ones and one during AstroSat observing period). Our SED modelling suggests that two compact emission regions originating at a different time outside the broad line region and moving away from the core with variation primarily in the jet electron spectra can explain the emission from the high, moderate, and low activity periods. The emissions from high and first low activity states are likely to have originated in the first region. The moderate and second low activity states are likely due to the second emission region with fresh particle acceleration/injection at a later time.

Temporal and Spectral Study of PKS B1222+216 Flares in 2014

“…These two ranges are also fitted with a straight line which shows 'brighter when softer ' scenario. This is in contrary to the trend mentioned in Bhattacharya et al (2021). Flare-B does not show any such correlation in the flux-index plot.…”

“…In this work, we mainly focus on both 2014 flares of PKS B1222+216. In Bhattacharya et al (2021), this activity is mentioned as a moderate-activity state (MS) and only a small portion (∼ 7 days) of the second flare was modelled with one zone leptonic scenario. In this work, we have studied both flares separately and presented spectral characterization and broadband modelling of the 2014 flare in great detail.…”

“…The detailed flare fitting in various sub bands provides information about underlying acceleration and cooling mechanism. In Bhattacharya et al (2021), the flaring activity in 2014 is considered as the medium flux (MS) state and SED modelling is only performed for flare-B with a duration of ∼7 days. In spite of the leptonic model scenario, the modelling…”

Multiwavelength study of the quiescent states of six brightest flat-spectrum radio quasars detected by Fermi-LAT

“…(vi) PKS B1222+216: Bhattacharya et al (2020) carried out detailed comparison between flaring and quiescent states and reported Fermi spectral indices of 2.5 during quiescence and 1.7-2.3 during flares, which is comparable to spectral index obtained in this work (2.6). They also did not mention resulting jet powers from SED modellings.…”

“…We selected the six FSRQs (CTA 102,3C 273,3C 279,3C 454.3, PKS 1510−089, and PKS B1222+216) from the Fermi-LAT monitored source list, also studied in Meyer, Scargle & Blandford (2019), which are known for exhibiting brightest γ -ray flares with average daily fluxes over 10 −5 cm −2 s −1 within 1σ statistical uncertainties above 100 MeV (Meyer et al 2019). Detailed multiwavelength studies on brightest γ -ray flares of all these sources have been done by various authors (CTA 102, Gasparyan et al 2018;3C 279, Bottacini et al 2016, Pittori et al 2018, Larionov et al 20203C 273, Rani et al 2013, Esposito et al 20153C 454.3, Diltz & Böttcher 2016; PKS 1510−089, Aleksić et al 2014;PKS B1222+216, Ackermann et al 2014, Bhattacharya et al 2020). Except 3C 273, for the other five sources comparative study on quiescent states with flares have been done (Hayashida et al 2012;Zacharias et al 2017;Acciari et al 2018;Boettcher & Baring 2019).…”