XRISM reveals low non-thermal pressure in the core of the hot, relaxed galaxy cluster Abell 2029

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2501.05514v1.pdf (1.1 MB)

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http://arxiv.org/abs/2501.05514

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https://doi.org/10.48550/arXiv.2501.05514
 http://hdl.handle.net/11603/37567

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UMBC Physics Department
UMBC Center for Space Sciences and Technology (CSST) / Center for Research and Exploration in Space Sciences & Technology II (CRSST II)
UMBC Faculty Collection

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Author/Creator ORCID

https://orcid.org/0000-0003-2704-599X
 https://orcid.org/0000-0001-7515-2779
 https://orcid.org/0000-0001-6665-2499
 https://orcid.org/0000-0002-8286-8094
 https://orcid.org/0000-0002-4656-6881

Date

2025-01-09

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journal articles
postprints
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Citation of Original Publication

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This work was written as part of one of the author's official duties as an Employee of the United States Government and is therefore a work of the United States Government. In accordance with 17 U.S.C. 105, no copyright protection is available for such works under U.S. Law.
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Subjects

Astrophysics - High Energy Astrophysical Phenomena

Abstract

We present XRISM Resolve observations of the core of the hot, relaxed galaxy cluster Abell 2029. We find that the line-of-sight bulk velocity of the intracluster medium (ICM) within the central 180 kpc is at rest with respect to the Brightest Cluster Galaxy, with a 3-sigma upper limit of |v_bulk| < 100 km/s. We robustly measure the field-integrated ICM velocity dispersion to be sigma_v = 169 +/- 10 km/s, obtaining similar results for both single-temperature and two-temperature plasma models to account for the cluster cool core. This result, if ascribed to isotropic turbulence, implies a subsonic ICM with Mach number M_3D ~ 0.21 and a non-thermal pressure fraction of 2%. The turbulent velocity is similar to what was measured in the core of the Perseus cluster by Hitomi, but here in a more massive cluster with an ICM temperature of 7 keV, the limit on non-thermal pressure fraction is even more stringent. Our result is consistent with expectations from simulations of relaxed clusters, but it is on the low end of the predicted distribution, indicating that Abell 2029 is an exceptionally relaxed cluster with no significant impacts from either a recent minor merger or AGN activity.