Tidal features in HSC-SSP early-type galaxies

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_*_>10^11^M_{sun}_ and redshift 0.05<z<0.15 using automated techniques. The Wide layer of HSC-SSP reaches a depth of ~28.5mag/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 ftidal, with a logarithmic slope of ~100. Within the stellar mass range we probe, we note that ftidal increases by a factor of 2 from M_*_~10^11^ to 10^12^M_{sun}_. We also perform a pair count to estimate the merger rate of these massive ETGs.