Multi-frequency temporal and spectral variability study of blazar PKS 1424−418

Abstract

A study of blazar PKS 1424−418 was carried out using multi-waveband data collected by the Fermi Large Area Telescope (Fermi-LAT), Swift X-Ray Telescope (Swift-XRT), Swift UltraViolet and Optical Telescope (Swift-UVOT), and Small and Moderate Aperture Research Telescope System (SMARTS) between MJD 56000 and MJD 56600 (2012 March 14–2013 November 4). Two flaring episodes were identified by analysing the gamma-ray light curve. Simultaneous multi-waveband spectral energy distributions (SEDs) were obtained for those two flaring periods. A cross-correlation analysis of infrared (IR)–optical and γ-ray data suggested that the emission originated from the same region. We have set a lower limit for the Doppler factor using the highest energy photon observed from this source during the flaring periods, which should be >12. The broad-band emission mechanism was studied by modelling the SED using the leptonic emission mechanism.

Broadband Spectro-temporal Study on Blazar TXS 1700+685

“…Our estimation of the magnetic field is in agreement with the previous estimation for which the equipartition value is similarly on the higher side (e.g. in PKS 1424-418; Abhir et al (2021b) for which the estimated magnetic field turns out to be ∼ 0.2 G), and is at variance with low equipartition value estimation corresponding to stronger magnetic fields (Buson et al 2014). The bulk Lorentz factor (Γ) and the Doppler factor (𝛿) are also significantly lower compared to what was obtained in Buson et al (2014).…”

Study of Temporal and Spectral variability for Blazar PKS 1830-211 with Multi-Wavelength Data

“…The pre-flare and post-flare states were found to be similar. The UV-optical emission of the source was dominated by the synchrotron emission rather than the thermal emission from the accretion disk, a trend also observed in our previous work on PKS 1424-418 (Abhir et al, 2021) and in the well-documented blazar 3C 273 (Jorstad et al, 2012). The X-ray and γ-ray flux were modelled to be originating from the IC scattering of photons from the BLR based on the correlated X-ray and γ-ray flux and the location of the emission region found in Section 5.1.…”

“…Most of the highest energy photons were from the flaring period between MJD 58570-58605, with some high energy γ-ray photons detected around MJD 58760 although no flaring was observed at this time (as can be seen in Fig 1). The highest energy photon was found to be 24.3 GeV, while many other blazars have been found to be the source of 30 − 50 GeV photons (for example, PKS 1424-418 in Abhir et al (2021), although at a lower redshift). This suggests the following two possibilities:…”

Imprint of “Local Opacity” Effect in Gamma-Ray Spectrum of Blazar Jet

“…High-activity periods are primarily linked to emission originating from energetic particles within the inner jet at parsec scales from black hole (Ezhikode et al 2022). Additionally, high Compton dominance in the source (q ∼ 30; Abhir et al 2021) indicates that accelerated high-energy electrons in the jet scatter a fraction of soft photons, emitting γrays. This process necessitates proximity of high-energy electrons to dominant sites of the soft photons, such as the accretion disk, BLR, or dusty torus.…”

“…The source recently exhibited exceptional outbursts during 2022, reaching 10 times the average flux level. The large black hole mass of 4.5 × 10 9 M e in PKS 1424-418 provides a possibility of strong accretion rate and thus sufficient seed photons from the BLR for the observed Compton dominance (q ∼ 30; Abhir et al 2021). The structure of the Letter is as follows: Section 2 discusses the methods and techniques, Section 3 presents the results, and a discussion is provided in Section 4.…”