Galaxy Cluster Scaling Relations between Bolocam Sunyaev-Zel'dovich Effect and Chandra X-ray Measurements

Abstract

We present scaling relations between the integrated Sunyaev-Zel'dovich Effect (SZE) signal, $Y_{\mathrm{SZ}}$, its X-ray analogue, $Y_{\mathrm{X}}\equiv M_{\mathrm{gas}}{T}_{\mathrm{X}}$, and total mass, $M_{\mathrm{tot}}$, for the 45 galaxy clusters in the Bolocam X-ray-SZ (BOXSZ) sample. All parameters are integrated within $r_{2500}$. $Y_{2500}$ values are measured using SZE data collected with Bolocam, operating at 140 GHz at the Caltech Submillimeter Observatory (CSO). The temperature, $T_{\mathrm{X}}$, and mass, $M_{\mathrm{gas},2500}$, of the intracluster medium are determined using X-ray data collected with Chandra, and $M_{\mathrm{tot}}$ is derived from $M_{\mathrm{gas}}$ assuming a constant gas mass fraction. Our analysis accounts for several potential sources of bias, including: selection effects, contamination from radio point sources, and the loss of SZE signal due to noise filtering and beam-smoothing effects. We measure the $Y_{2500}$--$Y_{\mathrm{X}}$ scaling to have a power-law index of $0.84\pm 0.07$, and a fractional intrinsic scatter in $Y_{2500}$ of $(21\pm 7)\%$ at fixed $Y_{\mathrm{X}}$, both of which are consistent with previous analyses. We also measure the scaling between $Y_{2500}$ and $M_{2500}$, finding a power-law index of $1.06\pm 0.12$ and a fractional intrinsic scatter in $Y_{2500}$ at fixed mass of $(25\pm 9)\%$. While recent SZE scaling relations using X-ray mass proxies have found power-law indices consistent with the self-similar prediction of 5/3, our measurement stands apart by differing from the self-similar prediction by approximately 5$\ddot{I}ƒ$. Given the good agreement between the measured $Y_{2500}$--$Y_{\mathrm{X}}$ scalings, much of this discrepancy appears to be caused by differences in the calibration of the X-ray mass proxies adopted for each particular analysis.

31 pages, 15 figures, accepted by ApJ 04/11/2015. This version is appreciably different from the original submission: it includes an entirely new appendix, extended discussion, and much of the material has been reorganized