The Sunyaev-Zel'dovich Effect at Five Arc-seconds: RXJ1347.5-1145 Imaged by ALMA

TL;DR

This paper presents the first high-resolution ALMA imaging of the thermal Sunyaev-Zel'dovich effect in a galaxy cluster, revealing detailed small-scale intracluster medium structures and demonstrating ALMA's capabilities for SZE observations.

Contribution

It provides the first high-resolution (5 arc-second) ALMA SZE image of a galaxy cluster, showcasing unprecedented spatial detail and analysis methods for future studies.

Findings

First ALMA SZE image at 5 arc-second resolution

Good agreement with X-ray electron pressure maps

Demonstrates ALMA's potential for detailed SZE imaging

Abstract

We present the first image of the thermal Sunyaev-Zel'dovich effect (SZE) obtained by the Atacama Large Millimeter/submillimeter Array (ALMA). Combining 7-m and 12-m arrays in Band 3, we create an SZE map toward a galaxy cluster RXJ1347.5-1145 with 5 arc-second resolution (corresponding to the physical size of 20 kpc/h), the highest angular and physical spatial resolutions achieved to date for imaging the SZE, while retaining extended signals out to 40 arc-seconds. The 1-sigma statistical sensitivity of the image is 0.017 mJy/beam or 0.12 mK_CMB at the 5 arc-second full width at half maximum. The SZE image shows a good agreement with an electron pressure map reconstructed independently from the X-ray data and offers a new probe of the small-scale structure of the intracluster medium. Our results demonstrate that ALMA is a powerful instrument for imaging the SZE in compact galaxy clusters with unprecedented angular resolution and sensitivity. As the first report on the detection of the SZE by ALMA, we present detailed analysis procedures including corrections for the missing flux, to provide guiding methods for analyzing and interpreting future SZE images by ALMA.