Browsing by Author "Cuevas, H"

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    Photometry of the central regions in a complete sample of high Bautz-Morgan-type Abell clusters.: I.: Observations and data calibration
    (2000) Quintana, H; Infante, L; Fouque, P; Carrasco, ER; Cuevas, H; Hertling, G; Nuñez, I
    We present CCD photometry of 209 southern Abell clusters selected according to Bautz-Morgan type I, I-II, and II. We have performed total photometry in the GUM r bandpass, classified stars and galaxies, and obtained structural parameters for the images. To estimate the photometric and structural errors on the CCD images and the completeness limits of our photometry, we performed realistic simulations of stars and galaxies and ran our classification algorithms. Here, we present central galaxy counts and metric photometry of the brightest cluster,:members, for which we give accurate positions, and compare this photometry with values in the literature. A linear magnitude-redshift relation has been derived from the tenth-ranked galaxy in each cluster. Photometric redshifts have been estimated for 57 clusters. We provide either spectroscopic or photometric redshifts for all the clusters in our sample. Further analysis of these data will be presented in further publications.
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    The cluster of galaxies Abell 970
    (2001) Sodré, L; Proust, D; Capelato, HV; Neto, GBL; Cuevas, H; Quintana, H; Fouqué, P
    We present a dynamical analysis of the galaxy cluster Abell 970 based on a new set of radial velocities measured at ESO, Pic du Midi and Haute-Provence observatories. Our analysis indicates that this cluster has a substructure and is out of dynamical equilibrium. This conclusion is also supported by differences in the positions of the peaks of the surface density distribution and X-ray emission, as well as by the evidence of a large-scale velocity gradient in the cluster. We also found a discrepancy between the masses inferred with the virial theorem and those inferred with the X-ray emission, which is expected if the galaxies and the gas inside the cluster are not in hydrostatic equilibrium. Abell 970 has a modest cooling ow, as is expected if it is out of equilibrium. We propose that cooling flows may have an intermittent behaviour, with phases of massive cooling flows being followed by phases without significant cooling flows after the accretion of a galaxy group massive enough to disrupt the dynamical equilibrium in the centre of the clusters. A massive cooling ow will be established again, after a new equilibrium is achieved.