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The time delay between star formation quenching and morphological transformation of galaxies in clusters: a phase–space view of EDisCS


Kshitija Kelkar

Professor of Astronomy

Gregory Rudnick

Yara L

Pascale Jablonka

John Moustakas

Bo Milvang-Jensen


We explore the possible effect of cluster environments on the structure and star formation histories of galaxies by analysing the projected phase–space (PPS) of intermediate-redshift clusters (0.4 z 0.8). HST I−band imaging data from the ESO Distant Cluster Survey (EDisCS) allow us to measure deviations of the galaxies' light distributions from symmetric and smooth profiles using two parameters, A res ('asymmetry') and RF F (residual flux fraction or 'roughness'). Combining these structural parameters with age-sensitive spectral indicators (H δA , H γA and D n 4000), we establish that in all environments younger star-forming galaxies of all morphologies are 'rougher' and more asymmetric than older, more quiescent ones. Combining a subset of the EDisCS clusters we construct a stacked PPS diagram and find a significant correlation between the position of the galaxies on the PPS and their stellar ages, irrespective of their morphology. We also observe an increasing fraction of galaxies with older stellar populations towards the cluster core, while the galaxies structural parameters (A res and RF F) do not seem to segregate strongly with PPS. These results may imply that, under the possible influence of their immediate cluster environment, galaxies have their star formation suppressed earlier, while their structural transformation happens on a longer timescale as they accumulate and age in the cluster cores.


Kelkar, K., Gray, M. E., Aragón-Salamanca, A., Rudnick, G., Jaffé, Y. L., Jablonka, P., …Milvang-Jensen, B. (2019). The time delay between star formation quenching and morphological transformation of galaxies in clusters: a phase–space view of EDisCS. Monthly Notices of the Royal Astronomical Society, 486(1), 868-884.

Journal Article Type Article
Acceptance Date Mar 27, 2019
Online Publication Date Mar 28, 2019
Publication Date Jun 1, 2019
Deposit Date Apr 9, 2019
Publicly Available Date Apr 9, 2019
Journal Monthly Notices of the Royal Astronomical Society
Print ISSN 0035-8711
Electronic ISSN 1365-2966
Publisher Oxford University Press
Peer Reviewed Peer Reviewed
Volume 486
Issue 1
Pages 868-884
Keywords galaxies: clusters: general, galaxies: elliptical and lenticular, cD, galaxies: evolution, galaxies: fundamental parameters, galaxies: spiral, galaxies: statistics
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