Alternation of the flickering morphology between the high and low state in MV Lyr

TL;DR

This study analyzes the evolution of frequency components in the light curve of MV Lyr during state transitions, revealing complex spectral changes and similarities with other cataclysmic variables and X-ray binaries.

Contribution

It provides detailed analysis of frequency component evolution in MV Lyr's light curve, highlighting complex spectral changes during state transitions and drawing parallels with other accreting systems.

Findings

Complex changes in power density spectra during state transitions.

Increase in low-frequency activity and decrease in high-frequency power.

Similarity of characteristic frequencies across different cataclysmic variables.

Abstract

AIMS: We studied unique data of a nova-like system MV Lyr during transition from the high to low state and vice versa taken by the Kepler space telescope. We were interested in evolution of frequency components found previously by Scaringi et al. in different data also obtained by Kepler. METHODS: We divided the light curve into 10 day segments and investigated the corresponding power density spectra. We searched for individual frequency components by fitting with Lorentzian functions. Additionally, we investigated the variability using averaged shot profiles calculated from the light curve divided into 10 equally spaces subsamples. RESULTS: We found very complex changes of the power density spectra. We focused our study onto three frequency components. Strong activity increase is seen at low frequencies. Contrariwise, the high frequency part of the spectrum strongly decreases in power with specific rise in characteristic frequencies of the individual components. We discuss various scenarios of this phenomenology as reprocessing of X-rays in a receding accretion disc or a radiation from a more active region at the outer disc. Finally, we show that various cataclysmic variables show similar characteristic frequencies in their power density spectra. These are dependent on activity stage, making the situation similar to X-ray binaries.