Optimizing measurements of cluster velocities and temperatures for CCAT-prime and future surveys

TL;DR

This paper forecasts how upcoming microwave surveys, especially with CCAT-prime, can improve measurements of galaxy cluster velocities and temperatures through multi-frequency Sunyaev-Zeldovich effect observations, enhancing cosmological insights.

Contribution

It introduces optimized measurement strategies and instrument configurations for CCAT-prime to accurately extract cluster velocities, temperatures, and optical depths from multi-frequency data.

Findings

CCAT-prime can measure and separate SZ effects in massive clusters.

Submillimeter data significantly improve component separation from dusty galaxies.

Optimal detector array configurations enhance signal extraction efficiency.

Abstract

Galaxy cluster velocity correlations and mass distributions are sensitive probes of cosmology and the growth of structure. Upcoming microwave surveys will enable extraction of velocities and temperatures from many individual clusters for the first time. We forecast constraints on peculiar velocities, electron temperatures, and optical depths of galaxy clusters obtainable with upcoming multi-frequency measurements of the kinematic, thermal, and relativistic Sunyaev-Zeldovich effects. The forecasted constraints are compared for different measurement configurations with frequency bands between 90 GHz and 1 THz, and for different survey strategies for the 6-meter CCAT-prime telescope. We study methods for improving cluster constraints by removing emission from dusty star forming galaxies, and by using X-ray temperature priors from eROSITA. Cluster constraints are forecast for several model cluster masses. A sensitivity optimization for seven frequency bands is presented for a CCAT-prime first light instrument and a next generation instrument that takes advantage of the large optical throughput of CCAT-prime. We find that CCAT-prime observations are expected to enable measurement and separation of the SZ effects to characterize the velocity, temperature, and optical depth of individual massive clusters ($\sim10^{15}\,M_\odot$). Submillimeter measurements are shown to play an important role in separating these components from dusty galaxy contamination. Using a modular instrument configuration with similar optical throughput for each detector array, we develop a rule of thumb for the number of detector arrays desired at each frequency to optimize extraction of these signals. Our results are relevant for a future "Stage IV" cosmic microwave background survey, which could enable galaxy cluster measurements over a larger range of masses and redshifts than will be accessible by other experiments.