Observability of the virialization phase of spheroidal galaxies with radio arrays

TL;DR

This paper explores the potential to observe the virialization phase of spheroidal galaxies using next-generation radio arrays by detecting thermal Sunyaev-Zel'dovich signals, providing insights into early galaxy formation.

Contribution

It demonstrates that future radio telescopes can detect galaxy-scale SZ signals from high-redshift proto-galaxies, advancing observational capabilities in galaxy formation studies.

Findings

Detection of galaxy-scale SZ signals is feasible with EVLA, ALMA, SKA.

Optimal observation frequencies are between 10-35 GHz.

Wide field options can significantly increase survey efficiency.

Abstract

In the standard galaxy formation scenario plasma clouds with a high thermal energy content must exist at high redshifts since the proto-galactic gas is shock heated to the virial temperature, and extensive cooling, leading to efficient star formation, must await the collapse of massive halos (as indicated by the massive body of evidence, referred to as "downsizing"). Massive plasma clouds are potentially observable through the thermal and kinetic Sunyaev-Zel'dovich effects and their free-free emission. We find that the detection of substantial numbers of galaxy-scale thermal SZ signals is achievable by blind surveys with next generation radio telescope arrays such as EVLA, ALMA and SKA. This population is even detectable with the 10% SKA, and wide field of view options at high frequency on any of these arrays would greatly increase survey speed. An analysis of confusion effects and of the contamination by radio and dust emissions shows that the optimal frequencies are those in the range 10-35 GHz. Predictions for the redshift distributions of detected sources are also worked out.