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K-CLASH: Direct evidence of environmental quenching in massive clusters at 0.3 < z < 0.6

Published onJun 01, 2020
K-CLASH: Direct evidence of environmental quenching in massive clusters at 0.3 < z < 0.6

It is well known that the environment a galaxy resides in plays a role in its evolution, with galaxies in dense clusters experiencing physical processes which do not occur in the “field”. Finding direct evidence of environmental quenching effects has proved tricky, however, with few “smoking-gun” results outside the local Universe. One route to finding such evidence is to build up a homogeneously-observed sample of galaxies residing in different environments. Whilst this is commonly done with multiplexed fibre or long-slit data, there are few such surveys targeting galaxy clusters with multiplexed integral-field units. The K-CLASH survey aims to address this gap (as well as filing in an important gap in redshift-space) by using the unique capabilities of the K-band Multi-Object Spectrograph (KMOS) to observe ~100s of star-forming galaxies in four massive CLASH fields at 0.3 < z < 0.6. In this talk, I will present measurements of galaxies residing in these CLASH clusters and compare them to a matched “control” sample of field galaxies along the same line of sight. We use K-CLASH's spatially resolved capabilities to show that the cluster sample have Hα discs which are less extended than their field counterparts. I also find that, whilst the Mass-Metallicity relations (MZR) of the samples are indistinguishable, there is an obvious relation between a galaxy’s location within the cluster phase-space and its residual around the MZR. By comparing to simulations and closed-box chemical evolution models, I infer the infall times of our cluster targets, discuss the environmental processes which explain these observations and speculate on the future evolutionary paths of our cluster sample.

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