The rms-flux relation in accreting white dwarfs: another nova-like variable and the first dwarf nova

TL;DR

This study detects the linear rms-flux relation in two accreting white dwarf systems, including the first observation in a dwarf nova during quiescence, supporting a universal origin of accretion variability across different compact objects.

Contribution

It provides the first detection of the rms-flux relation in a dwarf nova during quiescence, extending its observed ubiquity to white dwarf binaries.

Findings

Rms-flux relation observed in V1504 Cyg and KIC 8751494.

First detection of this relation in a dwarf nova during quiescence.

Supports a common physical origin of accretion variability across diverse systems.

Abstract

We report on the detection of the linear rms-flux relation in two accreting white dwarf binary systems: V1504 Cyg and KIC 8751494. The rms-flux relation relates the absolute root-mean-square (rms) variability of the light curve to its mean flux. The light curves analysed were obtained with the Kepler satellite at a 58.8 s cadence. The rms-flux relation was previously detected in only one other cataclysmic variable, MV Lyr. This result reenforces the ubiquity of the linear rms-flux relation as a characteristic property of accretion-induced variability, since it has been observed in several black hole binaries, neutron star binaries and active galactic nuclei. Moreover, its detection in V1504 Cyg is the first time the rms-flux relation has been detected in a dwarf nova-type CV during quiescence. This result, together with previous studies, hence points towards a common physical origin of accretion-induced variability, independent of the size, mass, or type of the central accreting compact object.