First Sardinia Radio Telescope detection of the Sunyaev-Zel'dovich effect at 18.6 GHz

TL;DR

This paper reports the first detection of the Sunyaev-Zel'dovich effect at 18.6 GHz using the Sardinia Radio Telescope, demonstrating its potential for high-resolution studies of galaxy clusters and intracluster plasma.

Contribution

The study presents the first SZ effect detection at 18.6 GHz with SRT, modeling the cluster properties and comparing results with Planck, showcasing SRT's capabilities for detailed SZ observations.

Findings

Detected SZ decrement in galaxy cluster MACS J1752+4440 at 18.6 GHz.

Estimated cluster parameters consistent with expectations for its mass.

Higher resolution detection compared to all-sky surveys like Planck.

Abstract

Galaxy clusters imprint a distinctive signature on the cosmic microwave background through the thermal Sunyaev-Zel'dovich (SZ) effect, which enables to study the intracluster plasma distribution and makes them powerful cosmological probes. We present the first Sardinia Radio Telescope (SRT) detection of the SZ effect in the galaxy cluster MACS J1752+4440 at 18.6 GHz, with a resolution of 0.9'. We detected a decrement in brightness toward the cluster centre, which we attributed to the thermal SZ effect. We modelled the signal using a spherically symmetric $\beta$ model for the electron density distribution and we employed a Bayesian retrieval to estimate the core radius, central electron density, and $\beta$ parameter of the cluster. We found values consistent with expectations for a galaxy cluster of the mass of MACS J1752+4440: a core radius of ($160 \pm 30$) kpc, a central electron density of ($2.5^{+0.7}_{-0.5} \cdot 10^{-3}$) cm$^{-3}$, and $\beta$=$0.6\pm0.1$. The mean Compton-$y$ parameter within a radius of 3.5' is $(2.6 \pm 0.3) \cdot 10^{-5}$, higher than the value reported by Planck, which is coherent considering the different resolution of the instruments and the modelling adopted. This work demonstrates the potential of the SRT to detect the onset of the SZ decrement at low frequencies, providing higher angular resolution than current all-sky surveys and enabling an improved reconstruction of the SZ decrement profile and the plasma distribution in the intracluster medium.