Low X-ray Luminosity Galaxy Clusters

J.L.Nilo Castellón , M.V. Alonso and collaborators.



We present the study of nineteen low X-ray luminosity galaxy clusters (L X ∼ 0.5–45 × 10 43 erg s −1 ), selected from the ROSAT Position Sensitive Proportional Counters (PSPC) Pointed Observations (Vikhlinin et al. 1998) and the revised version of Mullis et al. (2003) in the redshift range of 0.16 to 0.7.
Photometric data in different passbands were taken for eight galaxy clusters at Las Campanas Observatory; three clusters at Cerro Tololo Interamerican Observatory; and eight clusters at the Gemini Observatory. Spectroscopic data were collected for only four galaxy clusters using Gemini telescopes. With the photometry, the galaxies were defined based on the star-galaxy separation taking into account photometric parameters. The catalogues contain total and aperture magnitudes of galaxies within the 90% completeness limit. They are used together with structural parameters to study the galaxy morphology and to estimate photometric redshifts. With the spectroscopy, the derived galaxy velocity dispersion of our clusters ranged from 507 km s −1 for [VMF98]022 to 775 km s −1 for [VMF98]097, indicating signs of the presence of substructure. Cluster membership has been extensively discussed taking into account spectroscopic redshifts and photometric estimates. In this sense, the galaxies within a projected radius of 0.75 Mpc from the X-ray emission peak and with spectroscopic ∆V = 1σ or photometric ∆V ∼ 6000 km s −1 are considered members. These results will be used in forthcoming papers to study, among the main topics, the red cluster sequence, blue cloud and green populations; the galaxy luminosity function and cluster dynamics..