Deriving Galaxy Cluster Velocity Anisotropy Profiles from a Joint Analysis of Dynamical and Weak Lensing Data
Abstract
We present an analytic approach to lift the mass-anisotropy degeneracy in clusters of galaxies by utilizing the line-of-sight velocity dispersion of clustered galaxies jointly with weak lensing inferred masses. More specifically, we solve the spherical Jeans equation by assuming a simple relation between the line-of-sight velocity dispersion and the radial velocity dispersion and recast the Jeans equation as a Bernoulli differential equation that has a well-known analytic solution. We first test our method in cosmological N-body simulations and then derive the anisotropy profiles for 35 archival data galaxy clusters with an average redshift of < {z}c> =0.25. The resulting profiles yield a weighted average global value of < β (0.2≤slant R/{R}200≤slant 1)> =0.35+/- 0.28 (stat) ±0.15 (sys). This indicates that clustered galaxies tend to globally fall on radially anisotropic orbits. We note that this is the first attempt to derive velocity anisotropy profiles for a cluster sample of this size utilizing joint dynamical and weak lensing data.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- March 2019
- DOI:
- 10.3847/1538-4357/ab06fa
- arXiv:
- arXiv:1711.10018
- Bibcode:
- 2019ApJ...874...33S
- Keywords:
-
- dark matter;
- galaxies: clusters: general;
- galaxies: halos;
- galaxies: kinematics and dynamics;
- methods: analytical;
- Astrophysics - Cosmology and Nongalactic Astrophysics
- E-Print:
- 10 pages, 5 figures, published in ApJ