K+a galaxies in the zCOSMOS Survey: Physical properties of systems in their post-starburst phase
Creators: name: Vergani, D.
name: Zamorani, G.
name: Lilly, S. J.
name: Lamareille, F.
name: Halliday, C.
name: Scodeggio, M.
name: Vignali, C.
name: Ciliegi, P.
name: Bolzonella, M.
name: Bondi, M.
name: Kovac, K.
name: Knobel, C.
name: Zucca, E.
name: Caputi, K.
name: Pozzetti, L.
name: Bardelli, S.
name: Mignoli, M.
name: Iovino, A.
name: Carollo, C. M.
name: Contini, T.
name: Kneib, J. -P.
name: Fevre, O. Le
name: Mainieri, V.
name: Renzini, A.
name: Bongiorno, A.
name: Coppa, G.
name: Cucciati, O.
name: de la Torre, S.
name: de Ravel, L.
name: Franzetti, P.
name: Garilli, B.
name: Kampczyk, P.
name: Borgne, J. -F. Le
name: Brun, V. Le
name: Maier, C.
name: Pello, R.
name: Peng, Y.
name: Montero, E. Perez
name: Ricciardelli, E.
name: Silverman, J. D.
name: Tanaka, M.
name: Tasca, L.
name: Tresse, L.
name: Abbas, U.
name: Bottini, D.
name: Cappi, A.
name: Cassata, P.
name: Cimatti, A.
name: Guzzo, L.
name: Koekemoer, A. M.
name: Maccagni, A. Leauthaud D.
name: Marinoni, C.
name: McCracken, H. J.
name: Memeo, P.
name: Meneux, B.
name: Oesch, P.
name: Porciani, C.
name: Scaramella, R.
name: Capak, P.
name: Sanders, D.
name: Scoville, N.
name: Taniguchi, Y.
Publisher: name: arXiv
Year: 2009
Subjects: subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences
subject: FOS: Physical sciences

description: The identities of the main processes triggering and quenching star-formation in galaxies remain unclear. A key stage in evolution, however, appears to be represented by post-starburst galaxies. To investigate their impact on galaxy evolution, we initiated a multiwavelength study of galaxies with k+a spectral features in the COSMOS field. We examine a mass-selected sample of k+a galaxies at z=0.48-1.2 using the spectroscopic zCOSMOS sample. K+a galaxies occupy the brightest tail of the luminosity distribution. They are as massive as quiescent galaxies and populate the green valley in the colour versus luminosity (or stellar mass) distribution. A small percentage (&lt;8%) of these galaxies have radio and/or X-ray counterparts (implying an upper limit to the SFR of ~8Msun/yr). Over the entire redshift range explored, the class of k+a galaxies is morphologically a heterogeneous population with a similar incidence of bulge-dominated and disky galaxies. This distribution does not vary with the strength of the Hdelta absorption line but instead with stellar mass in a way reminiscent of the well-known mass-morphology relation. Although k+a galaxies are also found in underdense regions, they appear to reside typically in a similarly rich environment as quiescent galaxies on a physical scale of ~2-8Mpc, and in groups they show a morphological early-to-late type ratio similar to the quiescent galaxy class. With the current data set, we do not find evidence of statistical significant evolution in either the number/mass density of k+a galaxies at intermediate redshift with respect to the local values, or the spectral properties. Those galaxies, which are affected by a sudden quenching of their star-formation activity, may increase the stellar mass of the red-sequence by up to a non-negligible level of ~10%.
description: 17 pages, 9 figures. Accepted for publication in Astronomy and Astrophysics on 09/09/2009 (no changes wrt v1)