Peculiar Velocity Constraints from Five-Band SZ Effect Measurements Towards RX J1347.5-1145 with MUSIC and Bolocam from the CSO

TL;DR

This study uses five-band SZ effect measurements combined with X-ray data to constrain the optical depth and peculiar velocity of galaxy cluster RX J1347.5-1145, providing insights into its gas distribution and motion.

Contribution

First multi-frequency SZ analysis of RX J1347.5-1145 combining new submillimeter data with X-ray measurements to constrain ICM properties and cluster dynamics.

Findings

Measured ICM optical depth: $ au_e = 7.33^{+0.96}_{-0.97} imes 10^{-3}$

Determined cluster's line-of-sight velocity: $v_{pec} = -1040^{+870}_{-840}$ km/s

Results limited by measurement noise, with potential for improvement

Abstract

We present Sunyaev-Zel'dovich (SZ) effect measurements from wide-field images towards the galaxy cluster RX J1347.5-1145 obtained from the Caltech Submillimeter Observatory with the Multiwavelength Submillimeter Inductance Camera (MUSIC) at 147, 213, 281, and 337 GHz and with Bolocam at 140 GHz. As part of our analysis, we have used higher frequency data from Herschel-SPIRE and previously published lower frequency radio data to subtract the signal from the brightest dusty star-forming galaxies behind RX J1347.5-1145 and from the AGN in RX J1347.5-1145's BCG. Using these five-band SZ effect images, combined with X-ray spectroscopic measurements of the temperature of the intra-cluster medium (ICM) from Chandra, we constrain the ICM optical depth to be $\tau_e = 7.33^{+0.96}_{-0.97} \times 10^{-3}$ and the ICM line of sight peculiar velocity to be $v_{pec} = -1040^{+870}_{-840}$ km s$^{-1}$. The errors for both quantities are limited by measurement noise rather than calibration uncertainties or astrophysical contamination, and significant improvements are possible with deeper observations. Our best-fit velocity is in good agreement with one previously published SZ effect analysis and in mild tension with the other, although some or all of that tension may be because that measurement samples a much smaller cluster volume. Furthermore, our best-fit optical depth implies a gas mass slightly larger than the Chandra-derived value, implying the cluster is elongated along the line of sight.