First simultaneous optical/near-infrared imaging of an X-ray selected, high-redshift cluster of galaxies with GROND

Monthly Notices of The Royal Astronomical Society, 2007

Environment plays an important role in the evolution of the gas contents of galaxies. Gas deficiency of cluster spirals and the role of the hot intracluster medium (ICM) in stripping gas from these galaxies is a well studied subject. Loose groups with diffuse X-ray emmision from the intragroup medium (IGM) offer an intermediate environment between clusters and groups without a hot IGM. These X-ray bright groups have smaller velocity dispersion and lower temperature than clusters, but higher IGM density than loose groups without diffuse X-ray emission. A single dish comparative study of loose groups with and without diffuse X-ray emission from the IGM, showed that the galaxies in X-ray bright groups have lost more gas on average than the galaxies in non X-ray bright groups. In this paper we present GMRT HI observations of 13 galaxies from 4 X-ray bright groups: NGC5044, NGC720, NGC1550 and IC1459. The aim of this work is to study the morphology of HI in these galaxies and to see if the hot IGM has in any way affected their HI content or distribution. In addition to disturbed HI morphology, we find that most galaxies have shrunken HI disks compared to the field spirals. This indicates that IGM assisted stripping processes like ram pressure may have stripped gas from the outer edges of the galaxies.

Astronomy & Astrophysics, 2011

Astronomy and Astrophysics, 2004

The Astrophysical Journal, 2001

Nature, 1997

Monthly Notices of …, 2004

Astronomy and Astrophysics, 2007

1998

We discuss a method to build up and study a sample of distant galaxies, with 2<z<5, using the gravitational amplification effect in cluster-lenses for which the mass distribution is well known. The candidates are selected close to the critical lines at high-z, through photometric redshift estimates on a large wavelength range. With respect to other methods, this procedure allows to reduce the selection biases in luminosity, thanks to the cluster magnification of ~1 magnitude, and towards active SFRs when the near-IR domain is included. Some new results obtained with this technique are presented and discussed.

Monthly Notices of the Royal Astronomical Society, 2006