Galaxy environment and star formation

LAMBAS, D. G.; TISSERA, P. B.; MARTINEZ, H. J.; ALONSO, M. S.; COLDWELL, G.; O'MILL, A. L.

Prague, Czech Republic

Simposio; IAU Symposium: Galaxy Evolution Across the Hubble Time, International Astronomical Union; 2006

Union Astronómica Internacional (IAU)

We analyse different mechanisms by which environment affect star formation in galaxies. Both galaxy interactions, and the dense environments associated to groups and clusters are explored to shed light on the response of star formation activity to external conditions. We use Sloan DR4 galaxy data available, and pair and group catalogues constructed recently and correlate galaxy global star formation parameters to pair relative separation and relative velocity, parent-group virial mass, etc. We analyse galaxy colours, star formation rate indicator parameters, and metallicities derived from recent studies in the Sloan survey. The results obtained provide clues to the extent at which large scale structure is affecting the ongoing process of star formation in present-day galaxies. In pairs, we show how projected relative separation and radial velocity thresholds indicate the onset of significant star formation and changes in metallicity driven by the interactions. Also, we study the effects of the dense environment associated to groups which largely suppress star formation activity implying a different evolution of the bimodal colour distribution as compared to that of field galaxies.