# Exploring Cosmic Origins with CORE: Cluster Science

## TL;DR

The paper evaluates the potential of the future CORE space mission to detect and analyze galaxy clusters via the Sunyaev-Zeldovich effect, emphasizing the impact of telescope size on detection capabilities and cosmological constraints.

## Contribution

It provides detailed simulations and forecasts for CORE's cluster detection efficiency, mass measurement, and cosmological constraints, highlighting the importance of telescope size and complementarity with ground-based experiments.

## Key findings

- CORE can detect approximately 50,000 clusters with a 150 cm telescope.
- Increasing the mirror size by 30 cm boosts cluster yield by 25%.
- CORE can measure cluster masses through CMB lensing with sensitivities down to 10^{14} M_\

## Abstract

We examine the cosmological constraints that can be achieved with a galaxy cluster survey with the future CORE space mission. Using realistic simulations of the millimeter sky, produced with the latest version of the Planck Sky Model, we characterize the CORE cluster catalogues as a function of the main mission performance parameters. We pay particular attention to telescope size, key to improved angular resolution, and discuss the comparison and the complementarity of CORE with ambitious future ground-based CMB experiments that could be deployed in the next decade. A possible CORE mission concept with a 150 cm diameter primary mirror can detect of the order of 50,000 clusters through the thermal Sunyaev-Zeldovich effect (SZE). The total yield increases (decreases) by 25% when increasing (decreasing) the mirror diameter by 30 cm. The 150 cm telescope configuration will detect the most massive clusters ($>10^{14}\, M_\odot$) at redshift $z>1.5$ over the whole sky, although the exact number above this redshift is tied to the uncertain evolution of the cluster SZE flux-mass relation; assuming self-similar evolution, CORE will detect $\sim 500$ clusters at redshift $z>1.5$. This changes to 800 (200) when increasing (decreasing) the mirror size by 30 cm. CORE will be able to measure individual cluster halo masses through lensing of the cosmic microwave background anisotropies with a 1-$\sigma$ sensitivity of $4\times10^{14} M_\odot$, for a 120 cm aperture telescope, and $10^{14} M_\odot$ for a 180 cm one. [abridged]