Short-term optical variability of high-redshift QSO's

TL;DR

This study monitored high-redshift, high-luminosity radio-quiet quasars for short-term optical variability and found no significant fluctuations, suggesting such variability is rare in these objects and likely linked to jet activity.

Contribution

It provides the first systematic search for short-term optical variability in high-redshift, high-luminosity radio-quiet quasars, challenging previous claims of such variability.

Findings

No significant continuum variations detected (>0.01-0.02 mag)

Short-term variability in radio-quiet quasars is unlikely in UV

Variability, if present, may be due to jet processes

Abstract

This paper presents results of a search for short-term variability in the optical band of selected high-luminosity, high-redshift radio-quiet quasars. Each quasar has been monitored typically for 2 - 4 hours with a time resolution of 2 - 5 minutes and a photometric accuracy of about 0.01 - 0.02 mag. Due to the significant redshift (z>2), the covered wavelength range falls into the UV region (typically 1500 - 2500A). We found no statistical evidence for any continuum variations larger than 0.01 - 0.02 for any of the monitored objects. Our results suggest that the presence of a short-term variability in radio-quiet quasars is unlikely even in the UV region, contrary to reports by other authors. This conclusion holds true at least for high-luminosity (large black hole mass and accretion rate?) objects. The results are consistent with the idea that significant short-term (less than 1 hour) variations in AGN, where observed, should be attributed primarily to processes in a relativistic jet.