Optical Microvariability in Quasars: Spectral Variability

TL;DR

This paper introduces a method to identify whether optical microvariability in quasars originates from thermal processes in the accretion disk or non-thermal processes in the jet, based on simultaneous multi-band observations.

Contribution

The paper develops a novel observational technique to distinguish the origin of optical microvariability in quasars using nearly simultaneous multi-band data.

Findings

3 out of 9 microvariability events are thermal in origin.

3 out of 9 events are non-thermal in origin.

3 events could not be definitively classified.

Abstract

We present a method that we developed to discern where the optical microvariability (OM) in quasars originates: in the accretion disk (related to thermal processes) or in the jet (related to non-thermal processes). Analyzing nearly simultaneous observations in three different optical bands of continuum emission, we are able to determine the origin of several isolated OM events. In particular, our method indicates that from nine events reported by Ramirez et al. (2009), three of them are consistent with a thermal origin, three to non-thermal, and three cannot be discerned. The implications for the emission models of OM are briefly discussed.