The Local Cluster Substructure Survey (LoCuSS) aims to measure the relationship between the structure of galaxy clusters and the evolution of their dark matter and baryonic contents as well as the galaxies that inhabit them. LoCuSS is a multi-wavelength survey of a morphologically-unbiased sample of ~80 X-ray luminous clusters in the redshift range 0.15<z<0.30 drawn from the ROSAT All Sky Survey cluster catalogs, selected to have nH<7x1020cm-2 and be observable with Subaru/SuprimeCAM on Mauna Kea (-70°<dec<+70°). The sample is blind to the thermodynamical and hierarchical assembly history of the clusters, other than the use of X-ray luminosity as a proxy for mass-selection. The primary scientific objective of the full sample is to calibrate the cluster mass scaling relations based on X-ray, SZ-effect, and weak and/or strong lensing analyses, and constrain the dark matter profiles of clusters on both large and small scales. More information on the overall survey and its scientific aims can be found on the main LoCuSS website at Birmingham: http://www.sr.bham.ac.uk/locuss/

Here in Arizona, our focus is on a large multi-wavelength survey of the first batch of 30 clusters for which Subaru imaging had already been acquired to perform the weak lensing analyses. Over the last five years we have been steadily assembling an unrivalled multi-wavelength dataset in order to study the impact of cluster environment on galaxy evolution, comprising wide-field imaging from the Spitzer, Herschel and GALEX Space telescopes. We have also embarked on the Arizona Cluster Redshift Survey (ACReS) to obtain spectroscopy for a stellar mass selected sample of ~10,000 cluster galaxies to support the multi-wavelength survey and also perform dynamical analyses of the clusters and their surrounding large-scale structure.

The immediate scientific objective of this multi-wavelength survey is to obtain a complete and unbiased census of both star formation and nuclear activity for galaxies in and around massive clusters, fundamental to chart the systematic impact of the cluster environment on star formation and the interstellar medium of infalling spiral galaxies. This will ultimately allow us to characterize and identify the dominant physical processes which lie behind the classical SF-density relation and Butcher-Oemler effect, constrain which aspect(s) of the cluster environment drive the quenching (and triggering) of star formation in recently accreted spiral galaxies, and how long this quenching process takes. Using dynamical analyses and comparisons to cosmological simulations, we will statistically determine how long galaxies are able to retain their gas and dust contents, and continue forming stars once they have been accreted into the cluster. More details of the scientific motivation and background of the survey can be found here.

 

 
       

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