4MOST Consortium Survey 10: The Time-Domain Extragalactic Survey (TiDES)

The Time-Domain Extragalactic Survey (TiDES) is focused on the spectroscopic follow-up of extragalactic optical transients and variable sources selected from forthcoming large sky surveys such as that from the Large Synoptic Survey Telescope (LSST). TiDES contains three sub-surveys: (i) spectroscopic observations of supernova-like transients; (ii) comprehensive follow-up of transient host galaxies to obtain redshift measurements for cosmological applications; and (iii) repeat spectroscopic observations to enable the reverberation mapping of active galactic nuclei. Our simulations predict we will be able to classify transients down to $r = 22.5$ magnitudes (AB) and, over five years of 4MOST operations, obtain spectra for up to 30,000 live transients to redshift $z \sim 0.5$, measure redshifts for up to 50,000 transient host galaxies to $z \sim 1$ and monitor around 700 active galactic nuclei to $z \sim 2.5$.