HSC gLSB galaxies structures and SB properties

To answer the question 'How rare are they?', we estimate their volume density in the local Universe. A visual inspection of 120 deg^2^ covered by deep Subaru Hyper Suprime-Cam data was performed independently by four team members.

We detected 42 giant disky systems (30 of them isolated) at z <= 0.1 with either g-band 27.7 mag arcsec^-2^ isophotal radius or four disc scale lengths 4h => 50 kpc, 37 of which (including 25 isolated) had low central surface brightness ({mu}_0,g_ => 22.7 mag arcsec^-2^). This corresponds to volume densities of 4.70*10^-5^ Mpc^-3^ for all galaxies with giant extended discs and 4.04*10^-5^Mpc^-3^ for gLSBGs, which converts to ~12700 such galaxies in the entire sky out to z < 0.1.