X-ray observations of the galaxy cluster Abell 2029 to the virial radius

TL;DR

This study uses Suzaku X-ray observations to analyze the thermodynamic properties of galaxy cluster Abell 2029 out to its virial radius, revealing anisotropies and deviations from simple models.

Contribution

First detailed Suzaku-based analysis reaching the virial radius of Abell 2029, highlighting anisotropies and challenges in modeling cluster outskirts.

Findings

Significant temperature and entropy anisotropies detected.

Entropy profile rises less steeply than gravitational predictions.

Breakdown of spherical symmetry and hydrostatic equilibrium assumptions.

Abstract

We present Suzaku observations of the galaxy cluster Abell 2029, which exploit Suzaku's low particle background to probe the ICM to radii beyond those possible with previous observations (reaching out to the virial radius), and with better azimuthal coverage. We find significant anisotropies in the temperature and entropy profiles, with a region of lower temperature and entropy occurring to the south east, possibly the result of accretion activity in this direction. Away from this cold feature, the thermodynamic properties are consistent with an entropy profile which rises, but less steeply than the predictions of purely gravitational hierarchical structure formation. Excess emission in the northern direction can be explained due to the overlap of the emission from the outskirts of Abell 2029 and nearby Abell 2033 (which is at slightly higher redshift). These observations suggest that the assumptions of spherical symmetry and hydrostatic equilibrium break down in the outskirts of galaxy clusters, which poses challenges for modelling cluster masses at large radii and presents opportunities for studying the formation and accretion history of clusters.