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Astron. Astrophys. 353, 92-96 (2000)

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Interaction rate at z ~ 1

Vladimir P. Reshetnikov

Astronomical Institute of St.Petersburg State University, 198904 St.Petersburg, Russia (resh@astro.spbu.ru)

Received 8 June 1999 / Accepted 30 October 1999


We found 25 galaxies with probable tidal tails in the Hubble Deep Fields North and South at z=0.5-1.5. General characteristics of the selected tidal features are very close to characteristics of tidal tails of local interacting galaxies. Using objects with z=0.5-1.0, we found that volume density of galaxies with tidal tails changes with z as [FORMULA]. Therefore, we estimated the rate of close encounters between the galaxies of comparable mass leading to the formation of extended tidal structures. If this rate reflects the merger rate, our data support a steeply increasing merger rate at [FORMULA]1 and consistent with zero curvature universe.

Key words: galaxies: interactions – galaxies: photometry – galaxies: peculiar – galaxies: structure

© European Southern Observatory (ESO) 2000

Online publication: December 8, 1999