Optical Flickering of the recurrent nova RS Ophiuchi: amplitude - flux relation

TL;DR

This study investigates the flickering variability of the recurrent nova RS Ophiuchi, revealing a strong linear correlation between flickering amplitude and average flux across multiple bands, similar to other accreting systems.

Contribution

It provides the first detailed analysis of the amplitude-flux relation in RS Ophiuchi's flickering, demonstrating a linear dependence consistent across different wavelengths.

Findings

Flickering amplitude correlates strongly with average flux (correlation coefficient 0.85).

The amplitude-flux relation follows a linear power-law with index approximately 1.

The rms flickering amplitude is about 8% of the average flux.

Abstract

We report observations of the flickering variability of the symbiotic recurrent nova RS~Oph at quiescence in five bands ($UBVRI$). We find evidence of a correlation between the peak-to-peak flickering amplitude ($\Delta F$) and the average flux of the hot component ($F_{\rm av}$). The correlation is highly significant, with a correlation coefficient of 0.85 and a $p$-value of~$\sim 10^{-20}$. Combining the data from all wavebands, we find a dependence of the type $\Delta F \propto F^k_{\rm av}$, with power-law index $k = 1.02 \pm 0.04$ for the $UBVRI$ flickering of RS~Oph. Thus, the relationship between the amplitude of variability and the average flux of the hot component is consistent with linearity. The rms amplitude of flickering is on average 8 per cent ($\pm2$ per cent) of $F_{\rm av}$. The detected correlation is similar to that found in accreting black holes/neutron stars and cataclysmic variables. The possible reasons are briefly discussed. The data are available upon request from the authors.