NOAO >   Observing Info >   Approved Programs >   2016A-0397

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Program Information for 2016A-0397


PI: Anja von der Linden, Stanford U., anja@slac.stanford.edu
Address: 452 Lomita Mall, Stanford, CA 94305

CoI: Steven Allen, Stanford U.
CoI: Adam Wright, Stanford U.
CoI: Adam Mantz, Stanford U.
CoI: Douglas Applegate, Universitat Bonn
CoI: Patrick Kelly, UC Berkeley
CoI: Glenn Morris, Stanford U.

Title: Setting the Scale: Determining the Absolute Mass Normalization and Scaling Relations for Clusters at z~0.1

Abstract: We propose to establish a low-redshift anchorpoint for the absolute mass calibration of galaxy clusters, an essential prerequisite for precise measurements of dark energy from current and future cluster surveys. To do so, we propose DECam imaging of 30 massive, X-ray- selected clusters at $zsim0.1$ to estimate their masses via weak lensing. We propose {it ugriz} imaging, as robust photo-z estimates of background galaxies are essential for controlling systematic errors in weak lensing mass measurements to a few percent. The data requested here will more than double the number of clusters in cosmological cluster samples with accurate weak lensing mass estimates employing photo-z's, enabling us for the first time to determine the mass normalization of key mass--observable relations to within 5\%, and measure $sigma_8$ to 2\%. Together with existing X-ray observations, these data will allow us to measure the shape (deviations from a power- law?) and scatter (size, and deviations from log-normal?) of cluster scaling relations, key ingredients for relating survey observables to cluster masses. Additionally, these data will create a legacy dataset of massive, low-redshift cluster fields with robust photo-z estimates. This proposal is a continuation of a project already allocated significant time in 2013A and 2014A, but with substantial losses due to weather and technical issues.

Program Type: Long Term/Extragalactic

Scheduled Nights:
Run 1 (2016A):  CT-4m/DECam -- 2n on Apr 01 - Apr 02 2016
Run 1 (2017A):  CT-4m/DECam -- 3n on Jun 25 - Jun 30 2017
Run 2 (2016A):  CT-4m/DECam -- 4n on Jul 03 - Jul 06 2016


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NOAO >   Observing Info >   Approved Programs >   2016A-0397

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