Multi-wavelength temporal and spectral analysis of Blazar S5 1803+78

TL;DR

This study presents a comprehensive multi-wavelength analysis of blazar S5 1803+78, revealing its variability, emission region characteristics, and spectral energy distribution modeling during different activity states.

Contribution

It provides the first detailed multi-wavelength temporal and spectral analysis of S5 1803+78, including flare characterization and SED modeling with SSC under a one-zone leptonic scenario.

Findings

Three gamma-ray flares identified with day-scale variability.

Gamma-ray and optical emissions are co-spatial with zero time lag.

High flaring states require strong Doppler boosting in SED models.

Abstract

Blazars are a class of AGN, one of their jets is pointed towards the earth. Here, we report about the multi-wavelength study for blazar S5 1803+78 between MJD 58727 to MJD 59419. We analysed $\gamma$-ray data collected by Fermi-LAT, X-ray data collected by Swift-XRT \& NuSTAR, optical photons detected by Swift-UVOT \& TUBITAK observatory in Turkey. Three flaring states are identified by analysing the $\gamma$-ray light curve. A day scale variability is observed throughout the flares with the similar rise and decay times suggesting a compact emission region located close to the central engine. Cross-correlation studies are carried out between $\gamma$-ray, radio, and X-ray bands, and no significant correlation is detected. The $\gamma$-ray and optical emission are significantly correlated with zero time lag suggesting a co-spatial origin of them. A significant positive correlation between the R-I index and the V magnitude is observed. The broadband spectral energy distributions (SEDs) modeling was performed for all the flaring episodes as well as for one quiescent state for comparison. SEDs are best fitted with the synchrotron-self Compton (SSC) model under a one-zone leptonic scenario. The SED modeling shows that to explain the high flaring state strong Doppler boosting is required.