Thermal Sunyaev-Zeldovich measurements and cosmic infrared background leakage mitigation combining upcoming ground-based telescopes

TL;DR

This paper evaluates how upcoming ground-based telescopes FYST and SO LAT can improve measurements of the thermal Sunyaev-Zeldovich effect by reducing cosmic infrared background contamination through advanced signal extraction techniques.

Contribution

It demonstrates that combining FYST and SO LAT data with specialized linear combination methods significantly reduces CIB contamination in tSZ measurements, enhancing detection accuracy.

Findings

CIB residual noise is reduced by ~35% when combining telescopes.

A large scale window (ℓ 1800-3500) exists where tSZ can be measured without noise dominance.

High-frequency coverage of FYST improves CIB contamination mitigation.

Abstract

The Fred Young Submillimeter Telescope (FYST) and the Simons Observatory Large Aperture Telescope (SO\ LAT) will deliver unprecedented high-resolution measurements of microwave sky emissions. Notably, one of those microwave sky emissions, the thermal Sunyaev-Zeldovich (tSZ) signal, is an essential probe for cluster astrophysics and cosmology. However, an obstacle to its measurement is contamination by the cosmic infrared background (CIB), especially at high frequencies. Our goal is to assess the detection and purity of tSZ power spectrum measurements from these two telescopes. We demonstrate that FYST's high-frequency coverage helps lower CIB contamination and improves signal detection. We simulated the various components of the microwave sky at the frequencies, sensitivities, and beam sizes of the upcoming SO LAT and FYST telescopes using full-sky Hierarchical Equal Area isoLatitude Pixelisation (HEALPix) map templates from the Websky simulations and the Python Sky Model (PySM). We used a map-based internal linear combination (ILC) and a constrained ILC (CILC) to extract the tSZ signal and compute residual noises to assess CIB contamination and signal recovery. We find that the CIB's residual noise power spectrum in the ILC-recovered tSZ is lowered by $\sim 35\%$ on average over the scales $\ell \in [500,5000]$ when SO LAT and FYST are combined compared to when SO LAT is used alone. We find that when using CILC to deproject CIB, the combined abilities of SO LAT and FYST offer a large $\ell \in [1800,3500]$ window in which the recovered tSZ power spectrum is not noise dominated.