Low X-Ray Luminosity Galaxy Clusters: Main goals, sample selection, photometric and spectroscopic observations

NILO CASTELLÓN, JOSÉ LUIS; ALONSO, M. VICTORIA; GARCIA LAMBAS, DIEGO; VALOTTO, CARLOS; O'MILL, ANA LAURA; CUEVAS, HÉCTOR; CARRASCO, RODRIGO; RAMIREZ, A; ASTUDILLO, J.M; RAMOS, F; JAQUE, M; ULLOA, N; ORDENES, Y

ASTRONOMICAL JOURNAL

IOP PUBLISHING LTD

Lugar: Londres; Año: 2016 vol. 151

0004-6256

We present the study of nineteen low X-ray luminosity galaxy clusters (LX 0.5{45 1043 erg s1),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 to0.7.This is the introductory paper of a series presenting the sample selection, photometric and spectro-scopic observations and data reduction. Photometric data in dierent passbands were taken for eightgalaxy clusters at Las Campanas Observatory; three clusters at Cerro Tololo Interamerican Observa-tory; and eight clusters at the Gemini Observatory. Spectroscopic data were collected for only fourgalaxy clusters using Gemini telescopes.With the photometry, the galaxies were dened based on the star-galaxy separation taking into ac-count photometric parameters. For each galaxy cluster, the catalogues contain the PSF and aperturemagnitudes of galaxies within the 90% completeness limit. They are used together with structuralparameters to study the galaxy morphology and to estimate photometric redshifts. With the spec-troscopy, the derived galaxy velocity dispersion of our clusters ranged from 507 km s􀀀1 for [VMF98]022to 775 km s􀀀1 for [VMF98]097 with signs of substructure.Cluster membership has been extensively discussed taking into account spectroscopic and photo-metric redshift estimates. In this sense, members are the galaxies within a projected radius of 0.75Mpc from the X-ray emission peak and with clustercentric velocities smaller than the cluster velocity dispersion or 6000 km s1, respectively. These results will be used in forthcoming papers tostudy, among the main topics, the red cluster sequence, blue cloud and green populations; the galaxyluminosity function and cluster dynamics.