One thousand cataclysmic variables from the Catalina Real-time Transient Survey

TL;DR

This paper presents the largest sample of 1043 cataclysmic variables identified by CRTS, analyzing their properties, types, and detection completeness, revealing a predominance of low accretion rate systems and limitations of current survey methods.

Contribution

It provides the first large-scale spectroscopic identification of CRTS CVs and assesses their outburst behaviors and detection completeness, highlighting the survey's bias towards high accretion rate systems.

Findings

Largest sample of CVs from a single survey to date.

Most CVs are low accretion rate systems with long recurrence times.

Detection completeness is approximately 23.6%, with many CVs having low variability amplitudes.

Abstract

Over six years of operation, the Catalina Real-time Transient Survey (CRTS) has identified 1043 cataclysmic variable (CV) candidates --- the largest sample of CVs from a single survey to date. Here we provide spectroscopic identification of 85 systems fainter than g<19, including three AMCVn binaries, one helium-enriched CV, one polar and one new eclipsing CV. We analyse the outburst properties of the full sample and show that it contains a large fraction of low accretion rate CVs with long outburst recurrence times. We argue that most of the high accretion rate dwarf novae in the survey footprint have already been found and that future CRTS discoveries will be mostly low accretion rate systems. We find that CVs with white dwarf dominated spectra have significantly fewer outbursts in their CRTS light curves compared to disc-dominated CVs, reflecting the difference in their accretion rates. Comparing the CRTS sample to other samples of CVs, we estimate the overall external completeness to be 23.6 per cent, but show that as much as 56 per cent of CVs have variability amplitudes that are too small to be selected using the transient selection criteria employed by current ground-based surveys. The full table of CRTS CVs, including their outburst and spectroscopic properties examined in this paper, is provided in the online materials.