Optical monitoring of the z=4.40 quasar Q 2203+292

TL;DR

This study monitored the high-redshift quasar Q 2203+292 over eight years, revealing modest variability similar to lower-redshift quasars and providing insights into its broad line region mass and surrounding environment.

Contribution

First long-term optical monitoring of a z=4.40 quasar, analyzing its variability and environment to compare with lower-redshift quasars and estimate broad line region mass.

Findings

Quasar shows ~0.3 mag variability over monitoring period.

Variability properties are similar to lower-redshift quasars.

Lower limit of broad line region mass is 0.3-0.4 solar masses.

Abstract

We report Cousins R-band monitoring of the high-redshift (z=4.40) radio quiet quasar Q 2203+292 from May 1999 to October 2007. The quasar shows maximum peak-to-peak light curve amplitude of ~0.3 mag during the time of our monitoring, and ~0.9 mag when combined with older literature data. The rms of a fit to the light curve with a constant is 0.08 mag and 0.2 mag, respectively. The detected changes are at ~3-sigma level. The quasar was in a stable state during the recent years and it might have undergone a brightening event in the past. The structure function analysis concluded that the object shows variability properties similar to those of the lower redshift quasars. We set a lower limit to the Q 2203+292 broad line region mass of 0.3-0.4 M_odot. Narrow-band imaging search for redshifted Ly_alpha from other emission line objects at the same redshift shows no emission line objects in the quasar vicinity.