A Comparison and Joint Analysis of Sunyaev-Zel'dovich Effect Measurements from Planck and Bolocam for a set of 47 Massive Galaxy Clusters

TL;DR

This study compares Sunyaev-Zel'dovich effect measurements from Planck and Bolocam for 47 galaxy clusters, analyzing model fits, scaling relations, and implications for cluster mass estimates and cosmology.

Contribution

It provides a joint analysis of SZ data from Planck and Bolocam, introduces a variable outer slope in the gNFW model, and assesses mass bias and model consistency.

Findings

Good agreement between Bolocam and Planck SZ signals with a ratio of 1.069 ± 0.030.

The outer slope parameter β scales with mass but not significantly with redshift.

Planck's detection completeness aligns with Bolocam measurements, constraining the mass bias to (1-b) = 0.93 ± 0.06.

Abstract

We measure the SZ signal toward a set of 47 clusters with a median mass of $9.5 \times 10^{14}$ M$_{\odot}$ and a median redshift of 0.40 using data from Planck and the ground-based Bolocam receiver. When Planck XMM-like masses are used to set the scale radius $\theta_{\textrm{s}}$, we find consistency between the integrated SZ signal, $Y_{\textrm{5R500}}$, derived from Bolocam and Planck based on gNFW model fits using A10 shape parameters, with an average ratio of $1.069 \pm 0.030$ (allowing for the $\simeq 5$% Bolocam flux calibration uncertainty). We also perform a joint fit to the Bolocam and Planck data using a modified A10 model with the outer logarithmic slope $\beta$ allowed to vary, finding $\beta = 6.13 \pm 0.16 \pm 0.76$ (measurement error followed by intrinsic scatter). In addition, we find that the value of $\beta$ scales with mass and redshift according to $\beta \propto M^{0.077 \pm 0.026} \times (1+z)^{-0.06 \pm 0.09}$. This mass scaling is in good agreement with recent simulations. We do not observe the strong trend of $\beta$ with redshift seen in simulations, though we conclude that this is most likely due to our sample selection. Finally, we use Bolocam measurements of $Y_{500}$ to test the accuracy of the Planck completeness estimate. We find consistency, with the actual number of Planck detections falling approximately $1 \sigma$ below the expectation from Bolocam. We translate this small difference into a constraint on the the effective mass bias for the Planck cluster cosmology results, with $(1-b) = 0.93 \pm 0.06$.