Exploring the Masses of the Two Most Distant Gravitational Lensing Clusters at the Cosmic Noon

TL;DR

This study successfully measures the masses of the most distant galaxy clusters via weak gravitational lensing at redshifts around 1.8-2, confirming their consistency with current cosmological models despite observational challenges.

Contribution

First weak lensing mass measurements of galaxy clusters at redshifts near 2, demonstrating the feasibility of studying such distant objects with deep infrared imaging.

Findings

JKCS 041 has a virial mass of approximately 5.4 x 10^14 solar masses.

XLSSC 122 has a virial mass of approximately 3.3 x 10^14 solar masses.

Measured masses align with X-ray estimates, supporting current cosmological models.

Abstract

Observations over the past decade have shown that galaxy clusters undergo the most transformative changes during the $z = 1.5 - 2$ epoch. However, challenges such as low lensing efficiency, high shape measurement uncertainty, and a scarcity of background galaxies have prevented us from characterizing their masses with weak gravitational lensing (WL) beyond the redshift $z\sim1.75$. In this paper, we report the successful WL detection of JKCS 041 and XLSSC 122 at $z=1.80$ and $z=1.98$, respectively, utilizing deep infrared imaging data from the Hubble Space Telescope with careful removal of instrumental effects. These are the most distant clusters ever measured through WL. The mass peaks of JKCS 041 and XLSSC 122, which coincide with the X-ray peak positions of the respective clusters, are detected at the $\sim3.7\sigma$ and $\sim3.2\sigma$ levels, respectively. Assuming a single spherical Navarro-Frenk-White profile, we estimate that JKCS 041 has a virial mass of $M_{200c} = (5.4\pm1.6) \times 10^{14} M_{\odot}$ while the mass of XLSSC 122 is determined to be $M_{200c} = (3.3\pm1.8) \times 10^{14} M_{\odot}$. These WL masses are consistent with the estimates inferred from their X-ray observations. We conclude that although the probability of finding such massive clusters at their redshifts is certainly low, their masses can still be accommodated within the current $\Lambda$CDM paradigm.