Scaling relations from Sunyaev-Zel'dovich effect and Chandra X-ray measurements of high-redshift galaxy clusters

We present Sunyaev-Zel'dovich Effect (SZE) scaling relations for 38 massive galaxy clusters at redshifts 0.14 ≤ z≤ 0.89, observed with both the Chandra X-ray Observatory and the centimeter-wave SZE imaging system at the BIMA and OVRO interferometric arrays. An isothermal β-model with the central 100 kpc excluded from the X-ray data is used to model the intracluster medium and to measure global cluster properties. For each cluster, we measure the X-ray spectroscopic temperature, SZE gas mass, total mass, and integrated Compton y-parameters within r2500. Our measurements are in agreement with the expectations based on a simple self-similar model of cluster formation and evolution. We compare the cluster properties derived from our SZE observations with and without Chandra spatial and spectral information and find them to be in good agreement. We compare our results with cosmological numerical simulations and find that simulations that include radiative cooling, star formation, and feedback match well both the slope and normalization of our SZE scaling relations

Markov Chain Monte Carlo joint analysis of Chandra X-ray imaging spectroscopy and Sunyaev-Zeldovich Effect data

X-ray and Sunyaev-Zeldovich Effect data can be combined to determine the distance to galaxy clusters. High-resolution X-ray data are now available from the Chandra Observatory, which provides both spatial and spectral information, and Sunyaev-Zeldovich Effect data were obtained from the BIMA and OVRO arrays. We introduce a Markov chain Monte Carlo procedure for the joint analysis of X-ray and Sunyaev-Zeldovich Effect data. The advantages of this method are the high computational efficiency and the ability to measure simultaneously the probability distribution of all parameters of interest, such as the spatial and spectral properties of the cluster gas and also for derivative quantities such as the distance to the cluster. We demonstrate this technique by applying it to the Chandra X-ray data and the OVRO radio data for the galaxy cluster Abell 611. Comparisons with traditional likelihood-ratio methods reveal the robustness of the method. This method will be used in follow-up papers to determine the distances to a large sample of galaxy clusters.Comment: ApJ accepted, scheduled for ApJ 10 October 2004, v614 issue. Title changed, added more convergence diagnostic tests, Figure 7 converted to lower resolution for easier download, other minor change

Determination of the Cosmic Distance Scale from Sunyaev-Zel'dovich Effect and Chandra X-ray Measurements of High Redshift Galaxy Clusters

We determine the distance to 38 clusters of galaxies in the redshift range 0.14 < z < 0.89 using X-ray data from Chandra and Sunyaev-Zeldovich Effect data from the Owens Valley Radio Observatory and the Berkeley-Illinois-Maryland Association interferometric arrays. The cluster plasma and dark matter distributions are analyzed using a hydrostatic equilibrium model that accounts for radial variations in density, temperature and abundance, and the statistical and systematic errors of this method are quantified. The analysis is performed via a Markov chain Monte Carlo technique that provides simultaneous estimation of all model parameters. We measure a Hubble constant of 76.9 +3.9-3.4 +10.0-8.0 km/s/Mpc (statistical followed by systematic uncertainty at 68% confidence) for an Omega_M=0.3, Omega_Lambda=0.7 cosmology. We also analyze the data using an isothermal beta model that does not invoke the hydrostatic equilibrium assumption, and find H_0=73.7 +4.6-3.8 +9.5-7.6 km/s/Mpc; to avoid effects from cool cores in clusters, we repeated this analysis excluding the central 100 kpc from the X-ray data, and find H_0=77.6 +4.8-4.3 +10.1-8.2 km/s/Mpc. The consistency between the models illustrates the relative insensitivity of SZE/X-ray determinations of H_0 to the details of the cluster model. Our determination of the Hubble parameter in the distant universe agrees with the recent measurement from the Hubble Space Telescope key project that probes the nearby universe.Comment: ApJ submitted (revised version

X-ray and Sunyaev-Zel'dovich Effect Measurements of the Gas Mass Fraction in Galaxy Clusters

We present gas mass fractions of 38 massive galaxy clusters spanning redshifts from 0.14 to 0.89, derived from Chandra X-ray data and OVRO/BIMA interferometric Sunyaev-Zel'dovich Effect measurements. We use three models for the gas distribution: (1) an isothermal beta-model fit jointly to the X-ray data at radii beyond 100 kpc and to all of the SZE data,(2) a non-isothermal double beta-model fit jointly to all of the X-ray and SZE data, and (3) an isothermal beta-model fit only to the SZE spatial data. We show that the simple isothermal model well characterizes the intracluster medium (ICM) outside of the cluster core in clusters with a wide range of morphological properties. The X-ray and SZE determinations of mean gas mass fractions for the 100 kpc-cut isothermal beta-model are fgas(X-ray)=0.110 +0.003-0.003 +0.006-0.018 and fgas(SZE)=0.116 +0.005-0.005 +0.009-0.026, where uncertainties are statistical followed by systematic at 68% confidence. For the non-isothermal double beta-model, fgas(X-ray)=0.119 +0.003-0.003 +0.007-0.014 and fgas(SZE)=0.121 +0.005-0.005 +0.009-0.016. For the SZE-only model, fgas(SZE)=0.120 +0.009-0.009 +0.009-0.027. Our results indicate that the ratio of the gas mass fraction within r2500 to the cosmic baryon fraction is 0.68 +0.10-0.16 where the range includes statistical and systematic uncertainties. By assuming that cluster gas mass fractions are independent of redshift, we find that the results are in agreement with standard LambdaCDM cosmology and are inconsistent with a flat matter dominated universe.Comment: ApJ, submitted. 47 pages, 5 figures, 8 table

Sunyaev-Zel'dovich Effect Imaging of Massive Clusters of Galaxies at Redshift z > 0.8

We present Sunyaev-Zel'dovich Effect (SZE) imaging observations of three distant (z > 0.8) and highly X-ray luminous clusters of galaxies, Cl1226+33, Cl0152-13 and MS1054-03. Two of the clusters, Cl1226+33 and Cl0152-13, were recently discovered in deep ROSAT x-ray images. Their high X-ray luminosity suggests that they are massive systems which, if confirmed, would provide strong constraints on the cosmological parameters of structure formation models. Our Sunyaev-Zel'dovich Effect data provide confirmation that they are massive clusters similar to the well studied cluster MS1054-03. Assuming the clusters have the same gas mass fraction as that derived from SZE measurements of eighteen known massive clusters, we are able to infer their mass and electron temperature from the SZE data. The derived electron temperatures are 9.8, 8.7, and 10.4 keV, respectively, and we infer total masses of ~2 x 10^14 h^-1 Msun within a radius of 65 arcsec (340 h^{-1} kpc) for all three clusters. For Cl0152-13 and MS1054-03 we find good agreement between our SZE derived temperatures and those inferred from X-ray spectroscopy. No X-ray derived temperatures are available for Cl1226+33, and thus the SZE data provide the first confirmation that it is indeed a massive system. The demonstrated ability to determine cluster temperatures and masses from SZE observations without access to X-ray data illustrates the power of using deep SZE surveys to probe the distant universe.Comment: 9 pages, 1 figure, accepted for publication in ApJ Letter