# Sunyaev-Zel'dovich detection of the galaxy cluster Cl J1449+0856 at z = 1.99: the pressure profile in uv space

## TL;DR

This study detects the Sunyaev-Zel'dovich effect in a high-redshift galaxy cluster using ALMA, revealing pressure profile characteristics and emphasizing the importance of interferometric methods and galaxy emission subtraction.

## Contribution

First SZ detection of a z=2 galaxy cluster with pressure profile analysis in uv space, demonstrating the effectiveness of interferometry and emission subtraction techniques.

## Key findings

- Detected SZ decrement at 5σ significance.
- Derived mass constraints consistent with X-ray estimates.
- Observed pressure profile consistent with local clusters, with slight central flattening.

## Abstract

We present Atacama Large Millimetre Array and Atacama Compact Array observations of the Sunyaev-Zel'dovich effect in the z = 2 galaxy cluster Cl J1449+0856, an X-ray-detected progenitor of typical massive clusters in the present day Universe. While in a cleaned but otherwise untouched 92 GHz map of this cluster, little to no negative signal is visible, careful subtraction of known sub-millimetre emitters in the uv plane reveals a decrement at 5$\sigma$ significance. The total signal is -190$\pm$36 $\mu$Jy, with a peak offset by 5"-9" ($\sim$50 kpc) from both the X-ray centroid and the still-forming brightest cluster galaxy. A comparison of the recovered uv-amplitude profile of the decrement with different pressure models allows us to derive total mass constraints consistent with the $\sim$6$\times$10$^{13}$ M$_{\odot}$ estimated from X-ray data. Moreover, we find no strong evidence for a deviation of the pressure profile with respect to local galaxy clusters, although a slight tension at small-to-intermediate spatial scales suggests a flattened central profile, opposite to what seen in a cool core and possibly an AGN-related effect. This analysis of the lowest mass single SZ detection so far illustrates the importance of interferometers when observing the SZ effect in high-redshift clusters, the cores of which cannot be considered quiescent, such that careful subtraction of galaxy emission is necessary.