The intermediate-band dropout method: A new method to search for high-redshift galaxies

We propose a new method to search for high-redshift galaxies that is based on an intermediate-band dropout technique rather than the usual broad-band dropout one. In this method, we use an intermediate-band filter whose central wavelength is longer than 7000 A. This new method makes it possible to distinguish both very late-type stars, such as L and T dwarfs, and dusty galaxies at intermediate redshifts from real high-z Lyman break galaxies. The reason for this is that such interlopers do not show strong intermediate-band depression, although they have very red broad-band colors that are indicative of Lyman break galaxies (LBGs). Applying our new method to imaging data sets obtained with Suprime-Cam on the Subaru Telescope, we found a new sample of Lyman break galaxies at z ≃ 5.