# Extragalactic astrophysics with next-generation CMB experiments

## TL;DR

Next-generation CMB experiments will significantly advance extragalactic astrophysics by detecting high-redshift galaxies, proto-clusters, and various sources with unprecedented resolution and sensitivity, expanding our understanding of galaxy formation and evolution.

## Contribution

The paper highlights the potential of upcoming CMB experiments to discover and study a wide range of extragalactic objects, surpassing previous capabilities.

## Key findings

- Detection of high-z galaxies with ~60 pc resolution.
- Identification of proto-clusters at high redshift.
- Measurement of polarized emission from thousands of sources.

## Abstract

Planck, SPT and ACT surveys have clearly demonstrated that Cosmic Microwave Background (CMB) experiments, while optimised for cosmological measurements, have made important contributions to the field of extragalactic astrophysics in the last decade. Future CMB experiments have the potential to make even greater contributions. One example is the detection of high-z galaxies with extreme gravitational amplifications. The combination of flux boosting and of stretching of the images has allowed the investigation of the structure of galaxies at z ~3 with the astounding spatial resolution of about 60 pc. Another example is the detection of proto-clusters of dusty galaxies at high z when they may not yet possess the hot intergalactic medium allowing their detection in X-rays or via the Sunyaev-Zeldovich effect. Next generation CMB experiments, like PICO, CORE, CMB-Bharat from space and Simons Observatory and CMB-S4 from the ground, will discover several thousands of strongly lensed galaxies out to z~6 or more and of galaxy proto-clusters caught in the phase when their member galaxies where forming the bulk of their {stars. They will also detect tens of thousands of local dusty galaxies and thousands of radio sources at least up to z~5. Moreover they will measure the polarized emission of thousands of radio sources and of dusty galaxies at mm/sub-mm wavelengths.