Galaxy-galaxy interactions as triggers of star formation

Galaxy‐galaxy interactions represent the main physical processes that trigger substantial star formation in galaxies. In order to study the galaxy interactions effects on color and morphology of the galaxies in the fields of two radio galaxies at z ∼ 1, we combined optical‐NIR photometry and HST/WFPC2 morphology data from the Stanford et al. (2002) catalog, with HST/WFPC2 archival images. Using a strong pair isolation criterion in terms of the apparent angular separation and rest‐frame line‐of‐sight velocity difference, we obtained a sample of galaxy pairs in the studied fields. The fact that close interactions and mergers induce star‐forming episodes is confirmed by the presence of morphological disturbances and bluer optical‐NIR colors at many analyzed galaxies (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)