Measurement of the Relativistic Sunyaev–Zeldovich Correction in RX J1347.5-1145
Victoria Butler, Richard M. Feder, Tansu Daylan, A. Mantz, Dale Mercado, Alfredo Montaña, Stephen K. N. Portillo, Jack Sayers, Benjamin J. Vaughan, M. Zemcov, Adi Zitrin
Abstract
Abstract We present a measurement of the relativistic corrections to the thermal Sunyaev–Zel’dovich (SZ) effect spectrum, the rSZ effect, toward the massive galaxy cluster RX J1347.5-1145 by combining submillimeter images from Herschel-SPIRE with millimeter wavelength Bolocam maps. Our analysis simultaneously models the SZ effect signal, the population of cosmic infrared background galaxies, and the galactic cirrus dust emission in a manner that fully accounts for their spatial and frequency-dependent correlations. Gravitational lensing of background galaxies by RX J1347.5-1145 is included in our methodology based on a mass model derived from the Hubble Space Telescope observations. Utilizing a set of realistic mock observations, we employ a forward modeling approach that accounts for the non-Gaussian covariances between the observed astrophysical components to determine the posterior distribution of SZ effect brightness values consistent with the observed data. We determine a maximum a posteriori (MAP) value of the average Comptonization parameter of the intracluster medium (ICM) within R 2500 to be 〈 y 〉 2500 = 1.56 × 10 −4 , with corresponding 68% credible interval [1.42, 1.63] × 10 −4 , and a MAP ICM electron temperature of 〈 T sz 〉 2500 = 22.4 keV with 68% credible interval spanning [10.4, 33.0] keV. This is in good agreement with the pressure-weighted temperature obtained from Chandra X-ray observations, 〈 T x,pw 〉 2500 = 17.4 ± 2.3 keV. We aim to apply this methodology to comparable existing data for a sample of 39 galaxy clusters, with an estimated uncertainty on the ensemble mean 〈 T sz 〉 2500 at the ≃ 1 keV level, sufficiently precise to probe ICM physics and to inform X-ray temperature calibration.