Cut-off radii of galactic disks - A new statistical study on the truncation of galactic disks

We present the analysis of a CCD survey of 31 nearby (less than or equal to 110 Mpc) edge-on spiral galaxies. The three-dimensional one-component best fit models provide their disk-scalelengths h and for the first time their disk cut-off radii R-co. We confirm for this sample the existence of such s harp truncations, and find a significantly lower mean value of the distance indepen dent ratio R-co/h = 2.9 +/- 0.7 than the standard value of 4.5 oft en used in the literature. Our data show no correlation of these parameters with Hubble type, whereas we report a correlation between R-co/h and the d istance based scalelength in linear units. Compared to the Milky Way we fin d only lower values of R-co/h, explained either by possible selection effec ts or by the completely different techniques used. We discuss our data in r espect to present models for the origin of the cut-off radii, either as a r elict of the galaxy formation process, or as an evolutionary phenomenon.