Discovering Cataclysmic Variables from the Rubin Observatory LSST

Abstract The Vera C. Rubin Observatory’s Legacy Survey of Space and Time (LSST) will provide a windfall of new transients and variable sources. Here we have performed mock observation simulations to understand LSST’s expected detection rates for cataclysmic variables (CVs) with known large-amplitude variations. Under the thin-disk approximation for the distribution of CVs in our Galaxy, we found that only 20% of WZ Sge–type dwarf novae systems, representing the most energetic disk-driven outbursts in CVs, will be detected during outbursts by the LSST. Given their large amplitude (7–9 mag), only those brighter than 17.5 mag at outburst maximum are expected to have an r -band quiescence counterpart in individual scans. Thanks to the planned cadence of the LSST toward the Galactic center, ≈70% of the simulated outbursts will be detected twice or more on the discovery night, and two-thirds will be observed in different bands. CVs of the polar class, which display luminosity changes up to 4 mag, can be unbiasedly recovered to 22.5 mag with more than 100 detections over 10 yr of the LSST operation. Finally, we attempt to characterize the detection rate of micronovae bursts, and find that about 2.6% of the simulated sample will be observed as a ≥0.4 mag amplitude and ≤1 day duration spike in the long-term light curve. Overall, our results consolidate LSST’s capability to studying time-domain phenomena in CVs, and inform on how to plan and organize follow-up observation strategies on transients discovered by LSST.