Inverse Compton light curves of blazars under non-linear, time-dependent synchrotron-self Compton cooling

TL;DR

This paper models inverse Compton light curves of blazars considering non-linear, time-dependent SSC cooling, revealing unique spectral features and variability patterns that can help distinguish between different emission models.

Contribution

It extends previous work by calculating inverse Compton light curves including both SSC and external Compton processes with retardation effects, highlighting observable differences from linear models.

Findings

Non-linear SSC cooling causes distinctive spectral breaks.

Retardation effects partially obscure SSC signatures in light curves.

Different flux states and variability timescales can discriminate models.

Abstract

Blazars exhibit flares with a doubling time scale on the order of minutes. Such rapid flares are theoretically challenging and several {models} have been put forward to explain the fast variability. In this paper we continue the discussion concerning the effects of non-linear, time-dependent synchrotron self-Compton (SSC) cooling. In previous papers we were able to show that the non-linearity{, introduced by a time-dependent electron injection,} has severe consequences for both the spectral energy distribution (SED) and the monochromatic synchrotron light curve. The non-linear cooling introduces novel breaks in the SED, which are usually explained by complicated underlying electron distributions, while the much faster cooling of the SSC process {causes significant differences in the synchrotron light curves}. In this paper we calculate the inverse Compton light curves, taking into account both the SSC and the external Compton process. The light curves are calculated from the monochromatic intensities by introducing the retardation due to the finite size of the emission region and the geometry of the source. Even though some of the obvious effects of the SSC cooling are washed out by the retardation, there are still several observational constraints which could help to discriminate between the non-linear and the usual linear models, such as different flux states, temporal shapes or faster variability of the light curves at different energies.