Browsing by Author "Zelaya, P."
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- ItemDiffuse intracluster light at intermediate redshifts: intracluster light observations in an X-ray cluster at z=0.29(2011) Toledo, I.; Melnick, J.; Selman, F.; Quintana, H.; Giraud, E.; Zelaya, P.The diffuse intracluster light (ICL) contains a significant fraction of the total stellar mass in clusters of galaxies, and contributes in roughly equal proportion as the hot intracluster medium to the total baryon content of clusters. Because of the potential importance of understanding the origin of the ICL in the context of the formation and evolution of structure in the Universe, the field has recently undergone a revival both in the quality and quantity of observational and theoretical investigations. Because of cosmological dimming, the observational work has mostly concentrated on low-redshift clusters, but clearly observations at higher redshifts can provide interesting clues about the evolution of the diffuse component. In this paper we present the first results of a programme to characterize the ICL of intermediate-redshift clusters. We find that at z similar to 0.3, the X-ray cluster RXJ0054.0-2823 already has a significant ICL and that the fraction of the total light in the ICL and the brightest cluster galaxy (BCG) is comparable to that of similar clusters at lower redshift. We also find that the kinematics of the ICL is consistent with it being the remnant of tidally destroyed galaxies streaming in the central regions of the cluster, which has three central giant elliptical galaxies acting as an efficient 'galaxy grinding machine'. Our cluster has a bi-modal radial velocity distribution and thus two possible values for the velocity dispersion. We find that the cluster fits well in the correlation between BCG+ICL fraction and cluster mass for a range of velocity dispersions, leading us to question the validity of a relevant correlation between these two quantities.
- ItemGalaxy Evolution in a Pilot Survey up to z=1 and CDM Halos(2011) Giraud, E.; Melnick, J.; Gu, Q. -S.; Quintana, H.; Selman, F.; Toledo, I.; Zelaya, P.We study spectral evolution of galaxies in a magnitude limited sample of 550 galaxies from z = 1 down to z = 0.3 on a pencil beam of approximate to 10' x 10'. We concentrate on the large apparent cosmological structures along the line of sight, and we bin our individual galaxy spectra to obtain representative high S/N spectra based upon these structures. We divide the resulting average spectra in three groups to facilitate the analysis: galaxies with pure absorption line spectra, galaxies with emission lines and blue continua, and galaxies with emission lines and red continua. We revisit the question of downsizing in emission-line galaxies between z = 0.9 and z = 0.45 in our pencil-beam and find the following results: strong star formation in emission line galaxies, aging in emission line galaxies, and aging in absorption systems, are shifting from bright to faint systems as cosmological time increases. Each redshift bin is repopulated in new starbursts. Therefore at redshifts z <= 1 galaxy formation is downsizing both in luminosity and number density. Our observations indicate that at z <= 1 star formation and hierarchical structure formation of CDM halos are not in phase.
- ItemPERSISTENT C II ABSORPTION IN THE NORMAL TYPE Ia SUPERNOVA 2002fk(2014) Zelaya, P.; Clocchiatti, Alejandro; Cartier, R.; Hamuy, M.; Pignata, Giuliano; Foerster, F.; Folatelli, G.; Phillips, M.
- ItemProperties of extragalactic dust inferred from linear polarimetry of Type Ia Supernovae(2015) Patat, F.; Taubenberger, S.; Cox, N.; Baade, D.; Clocchiatti, Alejandro; Hoflich, P.; Maund, J.; Reilly, E.; Spyromilio, J.; Wang, L.; Wheeler, J. C.; Zelaya, P.
- ItemSpectropolarimetry of the Type IIb SN 2008aq(2016) Stevance, H. F.; Maund, J. R.; Baade, D.; Hoflich, P.; Patat, F.; Spyromilio, J.; Wheeler, J. C.; Clocchiatti, Alejandro; Wang, L.; Yang, Y.; Zelaya, P.