[Normal Galaxies, Clusters of Galaxies -- Oral ]

Cosmology Independent Measurement of the Gas Mass Fraction Using Chandra X-ray and Sunyaev-Zel'dovich Effect Measurements of High Redshift Clusters

Nicole Hasler, UA Huntsville
Esra Bulbul (UA Huntsville), Max Bonamente (UA Huntsville), Marshall Joy (NASA Marshall Space Flight Center), John Carlstrom (University of Chicago), Thomas Culverhouse (University of Chicago), David Hawkins (Caltech Owens Valley Radio Observatory), Ryan Hennessy (University of Chicago), James Lamb (Caltech Owens Valley Radio Observatory), Erik Leitch (University of Chicago), Daniel Marrone (University of Chicago), Amber Miller (Columbia University), Tony Mroczkowski (University of Penn), Stephen Muchovej (Caltech), Clem Pryke (University of Chicago), Matthew Sharp (University of Chicago), David Woody (Caltech Owens Valley Radio Observatory)

We present a joint Chandra and Sunyaev Zel'dovich Array (SZA) analysis method to determine the gas mass fraction independent of cosmology and demonstrate on Abell 2204. The advantage of using X-ray and Sunyaev Zel'dovich Effect observations is that it allows us to directly determine the angular diameter distance. We use a generalized form of the Navarro-Frenk-White (NFW) dark matter distribution together with a polytropic model for the hot plasma density, to determine an analytical solution for the density and temperature profiles. We then use these models to obtain the cluster mass of Abell 2204 using a Monte Carlo Markov Chain technique, and produce good fits at large radii. This is the first steps towards a measurement of the gas mass fraction as a function of redshift that can be used for the Allen et. al. (2008) method to constrain dark energy.