The spectral variability in radio-loud quasars

TL;DR

This study analyzes spectral variability in radio-loud quasars, revealing different variability trends between flat-spectrum and steep-spectrum types, and suggesting thermal emission influences in SSRQs.

Contribution

It provides new insights into the spectral variability patterns of radio-loud quasars and links variability to accretion disk emission in SSRQs.

Findings

Majority of FSRQs show bluer-when-brighter trend

SSRQs exhibit a correlation between Eddington ratio and variability

Spectral variability from spectroscopy confirms photometric results

Abstract

The spectral variability of a sample of 44 flat-spectrum radio quasars (FSRQs) and 18 steep-spectrum radio quasars (SSRQs) in the SDSS stripe 82 region is investigated. Twenty-five of 44 FSRQs show a bluer-when-brighter trend (BWB), while only one FSRQ shows a redder-when-brighter trend, which is in contrast to our previous results. Eight of 18 SSRQs display a BWB. We found an anti-correlation between the Eddington ratio and the variability amplitude in r band for SSRQs, which is similar to that in radio-quiet AGNs. This implies that the thermal emission from the accretion disk may be responsible for the variability in SSRQs. The spectral variability from the SDSS multi-epoch spectroscopy also shows BWB for several SSRQs, consistent with that from photometry.