NOAO >   Observing Info >   Approved Programs >   2016B-0278

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Program Information for 2016B-0278


PI: Anthony J Kremin, U. of Michigan, kremin@umich.edu
Address: Physics Department, 450 Church St, Ann Arbor, MI 48109 USA

CoI: August Evrard, U. of Michigan
CoI: Brian Nord, FNAL
CoI: Christopher J Miller, U. of Michigan
CoI: Marcos Lima, Stanford U.
CoI: David Gerdes, U. of Michigan
CoI: Marcos Lima, IAGUSP

Title: Constraining the Scatter in Galaxy Cluster Mass as a Function of Redshift via Dynamical Estimates

Abstract: The use of galaxy clusters for cosmological constraints depends upon a firm understanding of the scatter in relations between mass and observables. Such understanding requires knowledge of the true mass scatter of the cluster halo. Recent work has indicated that stacked dynamical mass estimates using the caustic technique (Gifford et al. 2016) can reduce scatter to $lesssim 15%$ of the true halo mass in simulations when $sim30$~clusters, each with $sim40-50$ galaxies, are used in the stack. We propose a combined Gemini-SOAR/CT-4m proposal to measure the stacked mass of three ensemble clusters at respective redshifts of z~$sim 0.1,~0.25-0.45,$~and~.55-0.75$; while simultaneously measuring the individual masses of each cluster used in the ensembles via the caustic technique. With individual caustic mass estimates having roughly 30-40% scatter from the true halo mass, by comparing these with the caustic ensemble masses that have $sim15$% scatter we can perform the first measurement of the galaxy cluster mass scatter evolution with redshift. We emphasize the use of archival data to reduce the number of proposed targets from 4500 galaxies to 1056.

Program Type: Standard/Extragalactic

Scheduled Nights:
Run 1 (2016B):  SOAR/Goodman -- 5n on Jan 19 - Jan 23 2017


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