The Massively Accreting Cluster A2029

TL;DR

This study combines spectroscopy, X-ray, and weak lensing data to analyze the structure, mass, and infall processes of galaxy cluster A2029 and its surroundings, revealing significant infalling groups and their future accretion.

Contribution

It provides a comprehensive multi-wavelength analysis of A2029, identifying infalling groups and estimating their masses and future accretion, which advances understanding of cluster growth.

Findings

A2033 and SIG are significant infalling groups with combined mass ~60% of A2029.

The mass estimates from different methods are consistent with known scaling relations.

A2029 is expected to accrete these groups within a few billion years.

Abstract

We explore the structure of galaxy cluster Abell 2029 and its surroundings based on intensive spectroscopy along with X-ray and weak lensing observations. The redshift survey includes 4376 galaxies (1215 spectroscopic cluster members) within 40 arcmin of the cluster center; the redshifts are included here. Two subsystems, A2033 and a Southern Infalling Group (SIG) appear in the infall region based on the spectroscopy as well as on the weak lensing and X-ray maps. The complete redshift survey of A2029 also identifies at least 12 foreground and background systems (10 are extended X-ray sources) in the A2029 field; we include a census of their properties. The X-ray luminosities $L_{X}$ - velocity dispersions ($\sigma_{cl}$) scaling relations for A2029, A2033, SIG, and the foreground/background systems are consistent with the known cluster scaling relations. The combined spectroscopy, weak lensing, and X-ray observations provide a robust measure of the masses of A2029, A2033, and SIG. The total mass of the infalling groups (A2033 and SIG) is $\sim 60\%$ of the M200 of the primary cluster, A2029. Simple dynamical consid- erations suggest that A2029 will accrete these subsystems in next few Gyr. In agreement with simulations and with other clusters observed in a similar redshift range, the total mass in the A2029 infall region is comparable with the A2029 M200 and will mostly be accreted in the long-term future.