K+a galaxies in the zCOSMOS survey: Physical properties of systems in their post-starburst phase

D. Vergani, G. Zamorani, S. Lilly, F. Lamareille, C. Halliday, M. Scodeggio, C. Vignali, P. Ciliegi, M. Bolzonella, M. Bondi, K. Kovač, C. Knobel, E. Zucca, K. Caputi, L. Pozzetti, S. Bardelli, M. Mignoli, A. Iovino, C. M. Carollo, T. ContiniJ.-P. Kneib, O. Le Fèvre, V. Mainieri, A. Renzini, A. Bongiorno, G. Coppa, O. Cucciati, S. de la Torre, L. de Ravel, P. Franzetti, B. Garilli, P. Kampczyk, J.-F. Le Borgne, V. Le Brun, C. Maier, R. Pello, Y. Peng, E. Perez Montero, E. Ricciardelli, J. D. Silverman, M. Tanaka, L. Tasca, L. Tresse, U. Abbas, D. Bottini, A. Cappi, P. Cassata, A. Cimatti, L. Guzzo, A. M. Koekemoer, A. Leauthaud, D. Maccagni, C. Marinoni, H. J. McCracken, P. Memeo, B. Meneux, P. Oesch, C. Porciani, R. Scaramella, P. Capak, D. Sanders, N. Scoville, Y. Taniguchi

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29 Citations (Scopus)


Aims: 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 the prevalence of these galaxies and their impact on galaxy evolution in general, we initiated a multiwavelength study of galaxies with k+a spectral features in the well-studied COSMOS field. Methods: We examine a mass-selected sample of k+a galaxies in the COSMOS field at z = 0.48-1.2 using the spectroscopic zCOSMOS sample. To classify galaxies in their k+a phase, we use a spectroscopic criterion, based on the amplitude of the Hδ absorption line and the absence of the [OII] emission line. We develop our analysis for a well-defined sample by imposing stringent confidence levels on the spectroscopic redshifts and spectral measurements. We compare our results for two mass-selected samples of star-forming and quiescent galaxies selected using a purely spectral classification scheme from the 10 000 zCOSMOS catalogue (i.e. , based on measurements of 4000 Å break and EW[OII]). Results: In our mass-limited 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 (
Original languageEnglish
Article numberA42
Number of pages17
JournalAstronomy and astrophysics
Publication statusPublished - Jan-2010


  • galaxies: evolution
  • galaxies: fundamental parameters
  • galaxies: luminosity function
  • mass function
  • cosmology: observations
  • galaxies: formation

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