Tidal structures of z similar to 1 galaxies in the Hubble Deep Field

An analysis of the images of objects in the Northern Hubble Space Telescope Deep Field has revealed twelve galaxies with tidal tails at redshifts from 0.5 to 1.5. The integrated characteristics of the newly discovered tidal s tructures are found to be similar to those of the tails of local interactin g galaxies. The space density of galaxies with tidal tails is found to depe nd on z as (1 + z)(4+/-1) (q(o) = 0.05), according to the data on objects w ith z = 0.5-1.0. The exponent decreases to 3.6 if barred galaxies are inclu ded. The change in the rate of close encounters between galaxies of compara ble masses (i.e., those that produce extended tidal structures) is estimate d. If the rate of galactic mergers is governed by the same process, our dat a are indicative of the rapid evolution of galaxy merger rate toward z simi lar to 1. (C) 2000 MAIK "Nauka/Interperiodica".