Maier, C. and Lilly, S. J. and Zamorani, G. and Scodeggio, M. and Lamareille, F. and Contini, T. and Sargent, M. T. and Scarlata, C. and Oesch, P. and Carollo, C. M. and Le Fèvre, O. and Renzini, A. and Kneib, J.-P. and Mainieri, V. and Bardelli, S. and Bolzonella, M. and Bongiorno, A. and Caputi, K. and Coppa, G. and Cucciati, O. and de la Torre, S. and de Ravel, L. and Franzetti, P. and Garilli, B. and Iovino, A. and Kampczyk, P. and Knobel, C. and Kovač, K. and Le Borgne, J. -F. and Le Brun, V. and Mignoli, M. and Pello, R. and Peng, Y. and Perez Montero, E. and Ricciardelli, E. and Silverman, J. D. and Tanaka, M. and Tasca, L. and Tresse, L. and Vergani, D. and Zucca, E. and Abbas, U. and Bottini, D. and Cappi, A. and Cassata, P. and Cimatti, A. and Fumana, M. and Guzzo, L. and Halliday, C. and Koekemoer, A. M. and Leauthaud, A. and Maccagni, D. and Marinoni, C. and McCracken, H. J. and Memeo, P. and Meneux, B. and Porciani, C. and Pozzetti, L. and Scaramella, R. (2009) The Dependence of Star Formation Activity on Stellar Mass Surface Density and Sersic Index in zCOSMOS Galaxies at 0.5 < z < 0.9 Compared with SDSS Galaxies at 0.04 < z < 0.08. Astrophysical Journal, 694 (2). pp. 1099-1114. ISSN 0004-637X http://resolver.caltech.edu/CaltechAUTHORS:20090902-133644391
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In order to try to understand the internal evolution of galaxies and relate this to the global evolution of the galaxy population, we present a comparative study of the dependence of star formation rates on the average surface mass densities (Σ_(M)) of galaxies at 0.5 < z < 0.9 and 0.04 < z < 0.08, using the zCOSMOS and Sloan Digital Sky Survey (SDSS) surveys, respectively. We derive star formation rates, stellar masses, and structural parameters in a consistent way for both samples, and apply them to samples that are complete down to the same stellar mass at both redshifts. We first show that the characteristic step-function dependence of median specific star formation rate (SSFR) on Σ_(M) in SDSS, seen by Brinchmann et al., is due to the change over from predominantly disk galaxies to predominantly spheroidal galaxies at the surface mass density logΣ_(Mchar) ~ 8.5 at which the SSFR is seen to drop. Turning to zCOSMOS, we find a similar shape for the median SSFR-Σ_(M) relation, but with median SSFR values that are about 5-6 times higher than for SDSS, across the whole range of Σ_(M), and in galaxies with both high and low Sersic indices. This emphasizes that galaxies of all types are contributing, proportionally, to the global increase in star formation rate density in the Universe back to these redshifts. The Σ_(Mchar) "step" shifts to slightly higher values of Σ M in zCOSMOS relative to SDSS, but this can be explained by a modest differential evolution in the size-mass relations of disk and spheroid galaxies. For low Sersic index galaxies, there is little change in the size-mass relation, as seen by Barden et al., although we suggest that this does not necessarily imply inside-out growth of disks, at least not in this redshift range. On the other hand, there is a modest evolution in the stellar mass-size relation for high Sersic index galaxies, with galaxies smaller by ~25% at z ~ 0.7. Taken together these produce a modest increase in Σ_(Mchar). Low Sersic index galaxies have a SSFR that is almost independent of Σ_(M), and the same is probably also true of high Sersic index galaxies once obvious disk systems are excluded.
|Additional Information:||© 2009 American Astronomical Society. Print publication: Issue 2 (2009 April 1); received 2008 July 29; accepted for publication 2009 January 1; published 2009 March 23. We would like to thank the anonymous referee for his or her suggestions and comments.We also want to thank M. Ciccolini and M. Aller for their help for testing the reliability of COSMOS size measurements. C.M. acknowledges support from the Swiss National Science Foundation. This work has been supported in part by grant ASI/COFIS/WP3110.|
|Subject Keywords:||galaxies: evolution; galaxies: high-redshift|
|Official Citation:||The Dependence of Star Formation Activity on Stellar Mass Surface Density and Sersic Index in zCOSMOS Galaxies at 0.5 < z < 0.9 Compared with SDSS Galaxies at 0.04 < z < 0.08 C. Maier, S. J. Lilly, G. Zamorani, M. Scodeggio, F. Lamareille, T. Contini, M. T. Sargent, C. Scarlata, P. Oesch, C. M. Carollo, O. Le Fèvre, A. Renzini, J.-P. Kneib, V. Mainieri, S. Bardelli, M. Bolzonella, A. Bongiorno, K. Caputi, G. Coppa, O. Cucciati, S. de la Torre, L. de Ravel, P. Franzetti, B. Garilli, A. Iovino, P. Kampczyk, C. Knobel, K. Kovač, J.-F. Le Borgne, V. Le Brun, M. Mignoli, R. Pello, Y. Peng, E. Perez Montero, E. Ricciardelli, J. D. Silverman, M. Tanaka, L. Tasca, L. Tresse, D. Vergani, E. Zucca, U. Abbas, D. Bottini, A. Cappi, P. Cassata, A. Cimatti, M. Fumana, L. Guzzo, C. Halliday, A. M. Koekemoer, A. Leauthaud, D. Maccagni, C. Marinoni, H. J. McCracken, P. Memeo, B. Meneux, C. Porciani, L. Pozzetti, and R. Scaramella 2009 ApJ 694 1099-1114 doi: 10.1088/0004-637X/694/2/1099|
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|Deposited By:||Jason Perez|
|Deposited On:||11 Sep 2009 20:50|
|Last Modified:||26 Dec 2012 11:18|
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