Seminar @ DF-AS - R. De Propris - The evolution of galaxy structure in the CLASH clusters (and beyond)

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06/15/2016 - 11:30
Event until: 
06/15/2016 - 12:30
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We use HST images in rest-frame B and R for 25 CLASH clusters and four clusters at z > 1 to measure the evolution of galaxy structure (effective radius, Sersic indices and axial ratios) and the colour gradients for red sequence cluster members. Our results show that at z > 0.8 there is a significant contribution from red disks, resembling ‘anemic’ spirals, on the red sequence. While massive and bright galaxies appear to be classical ellipticals, the fainter systems around L* and fainter appear to be quiescent or recently quenched spirals. We show that these galaxies have large, age-related, colour gradients at z > 1 that disappear at z < 0.6, leaving the pristine metallicity gradient belonging to the spheroids. This suggests that the young disks were quenched at z~1.5 and have disappeared by z ~0.6 at least. Our results imply that possibly all ‘ellipticals’ may contain residual disks that have largely faded and are hidden at lower redshifts.


Villa Bazzoni

A. Biviano
Last update: 06-13-2016 - 12:28