Similar shot profile morphology of fast variability in a cataclysmic variable, X-ray binary, and blazar: The MV Lyrae case

¹ Advanced Technologies Research Institute, Faculty of Materials Science and Technology in Trnava, Slovak University of Technology in Bratislava, Bottova 25, 917 24 Trnava, Slovakia
e-mail: andrej.dobrotka@stuba.sk
² Department of Physics, Nihon University, 1-8 Kanda-Surugadai, Chiyoda-ku, Tokyo 101-8308, Japan
³ Department of Astronomy, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan

Received: 4 February 2019
Accepted: 23 August 2019

Abstract

Context. The cataclysmic variable MV Lyr has been found to be present in the Kepler field, yielding a light curve with the duration of almost 1500 days with 60 s cadence. Such high quality data of this nova-like system with obvious fast optical variability reveal multi-component power density spectra, as shown by previous works.

Aims. Our goal is to study the light curve from a different point of view and perform a shot profile analysis. We search for characteristics that have not been discovered with standard methods based on power density spectrum.

Methods. The shot profile method identifies individual shots in the light curve and averages these shots to reveal all substructures with typical timescales. We also tested the robustness of our analysis using a simple shot noise model. Although the principle of this method is not completely physically correct, we used it as a purely phenomenological approach.

Results. We obtain mean profiles with multi-component features. The shot profile method distinguishes substructures with similar timescales which appear as a single degenerate feature in power density spectra. Furthermore, this method yields the identification of another high frequency component in the power density spectra of Kepler and XMM-Newton data that have not been detected so far. Moreover, we found side lobes accompanied with the central spike, making the profile very similar to the Kepler data of blazar W2R 1926+42 and the Ginga data of Cyg X-1. All three objects show similar timescale ratios of the rising versus declining part of the central spikes, while the two binaries also have similar rising profiles of the shots described by a power-law function.

Conclusions. The similarity of both binary shot profiles suggests that the shots originate from the same origin, namely, aperiodic mass accretion in the accretion disc. Moreover, the similarity with the blazar may imply that the ejection fluctuations in the blazar jet are connected to accretion fluctuations driving the variability in binaries. This points out the connection between the jet and the accretion disc.