Testing ΛCDM Using Galaxy Dynamics
Abstract
For the first time, we tested a key outcome in the canonical cosmological model: the contributions of mergers with different mass ratios to cluster-size halo growth. Testing the canonical cosmological model is one of the primary science goals of CLASH, the Cluster Lensing and Supernova survey with Hubble. Here in CLASH, we dynamically analyzed 7 galaxy clusters with an average of 286 cluster members using data from MMT/HECTOSPEC and VLT/VIMOS. We identified cluster members from observed line-of-sight velocities and removed interlopers using the caustics method. For each cluster, we identified infalling and accreted halos using two different halo finders (overdensity and friends-of-friends) and estimated their masses. From these halos' masses, we estimated the contribution of different mass ratios to halo growth. We found in our redshift interval, on average, that halos with ~10% of the cluster's mass contribute more than halos with ~ 50% of the cluster's mass. In addition, we inferred that about 0.28 ± 0.04 of the clusters' mass is contributed by halos with mass ratio, ξ, of 0.01 ≲ ξ ≲ 0.6. These values are in agreement with our expectations, which are based on the Millennium simulations.
- Publication:
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American Astronomical Society Meeting Abstracts #221
- Pub Date:
- January 2013
- Bibcode:
- 2013AAS...22132301L