SIMBAD references

Here we present a statistical study on tidal features around massive early-type galaxies (ETGs). Utilizing the imaging data of the Hyper Suprime-Cam Subaru Strategic Program (HSC-SSP), we measure the flux fraction of tidal features (f_tidal) in 2649 ETGs with stellar mass M_* > 10¹¹ M_⊙ and redshift 0.05 < z < 0.15 using automated techniques. The Wide layer of HSC-SSP reaches a depth of ∼28.5 mag arcsec^–2 in the i band. Under this surface brightness limit, we find that about 28% of these galaxies harbor prominent tidal features with f_tidal > 1%, among which the number of ETGs decreases exponentially with f_tidal, with a logarithmic slope of ∼100. Within the stellar mass range we probe, we note that f_tidal increases by a factor of 2 from M_* ≈ 10¹¹ to 10¹² M_⊙. We also perform a pair count to estimate the merger rate of these massive ETGs. Combining the merger rates with f_tidal, we estimate that the typical lifetime of tidal features is ∼3 Gyr, consistent with previous studies.