K a galaxies in the zCOSMOS Survey: Physical properties of systems in their post-starburst phase - Astrophysics > Cosmology and Nongalactic AstrophysicsReportar como inadecuado




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Abstract: The identities of the main processes triggering and quenching star-formationin galaxies remain unclear. A key stage in evolution, however, appears to berepresented by post-starburst galaxies. To investigate their impact on galaxyevolution, we initiated a multiwavelength study of galaxies with k+a spectralfeatures in the COSMOS field. We examine a mass-selected sample of k+a galaxiesat z=0.48-1.2 using the spectroscopic zCOSMOS sample. K+a galaxies occupy thebrightest tail of the luminosity distribution. They are as massive as quiescentgalaxies and populate the green valley in the colour versus luminosity orstellar mass distribution. A small percentage <8% of these galaxies haveradio 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 galaxiesis morphologically a heterogeneous population with a similar incidence ofbulge-dominated and disky galaxies. This distribution does not vary with thestrength of the Hdelta absorption line but instead with stellar mass in a wayreminiscent of the well-known mass-morphology relation. Although k+a galaxiesare also found in underdense regions, they appear to reside typically in asimilarly rich environment as quiescent galaxies on a physical scale of~2-8Mpc, and in groups they show a morphological early-to-late type ratiosimilar to the quiescent galaxy class. With the current data set, we do notfind evidence of statistical significant evolution in either the number-massdensity of k+a galaxies at intermediate redshift with respect to the localvalues, or the spectral properties. Those galaxies, which are affected by asudden quenching of their star-formation activity, may increase the stellarmass of the red-sequence by up to a non-negligible level of ~10%.



Autor: D. Vergani, G. Zamorani, S.J. Lilly, F. Lamareille, C. Halliday, M. Scodeggio, C. Vignali, P. Ciliegi, M. Bolzonella, M. Bondi, K

Fuente: https://arxiv.org/







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