Rubin Observatory’s Survey Strategy Performance for Tidal Disruption Events

Abstract

Tidal disruption events (TDEs) are rare transients, which are considered as promising tools for probing supermassive black holes in quiescent galaxies. The majority of the ≈60 known TDEs have been discovered with time-domain surveys in the last two decades. Currently, ≈10 TDEs are discovered per year, and this number will increase with the Legacy Survey of Space and Time (LSST) at the Rubin Observatory. This work evaluates LSST survey strategies in view of their performance in identifying TDEs. We assume that TDEs can be identified photometrically based on their colors, particularly in the u band, and will be scientifically useful if we can detect the light-curve peak to derive physical quantities. We define the requirements for the Rubin light curves that are needed to achieve this (detections prepeak, postpeak, and in different bands to measure color). We then inject model light curves into the Operations Simulator and calculate the fractions of TDEs passing our requirements for several strategies. We find that under the baseline strategy, ≈1.5% of simulated TDEs fulfill our detection criteria, while this number increases when more time is devoted to u -band observations. An ideal observing strategy for the photometric identification of TDEs would have longer u -band exposures, which should not come at the expense of fewer u -band visits. A filter distribution weighted toward more observing time in bluer bands, intranight visits in different filters, and strategies with frequent sampling leading to higher-quality light curves are preferred. We find that these strategies benefiting TDE science do not impact significantly other science cases.

Keywords

• Tidal disruption
• Surveys
• Black holes