The Radial Acceleration Relation in CLASH Galaxy Clusters

Yong Tian; Keiichi Umetsu; Chung-Ming Ko; Megan Donahue; I-Non Chiu

doi:10.3847/1538-4357/ab8e3d

paper

The Radial Acceleration Relation in CLASH Galaxy Clusters

arXiv:2001.08340 · doi:10.3847/1538-4357/ab8e3d

Abstract

The radial acceleration relation (RAR) in galaxies describes a tight empirical scaling law between the total acceleration $g_{tot} (r) = G M_{tot} (< r) / r^{2}$ observed in galaxies and that expected from their baryonic mass $g_{bar} (r) = G M_{bar} (< r) / r^{2}$ , with a characteristic acceleration scale of $g_{†} ≃ 1.2 \times 1 0^{- 10}$ ms $^{- 2}$ . Here, we examine if such a correlation exists in galaxy clusters using weak-lensing, strong-lensing, and X-ray data sets available for 20 high-mass clusters targeted by the CLASH survey. By combining our CLASH data with stellar mass estimates for the brightest cluster galaxies (BCGs) and accounting for the stellar baryonic component in clusters, we determine, for the first time, an RAR on BCG--cluster scales. The resulting RAR is well described by a tight power-law relation, $g_{tot} \propto g_{bar}^{0.5 1_{- 0.05}^{+ 0.04}}$ , with lognormal intrinsic scatter of $14. 7_{- 2.8}^{+ 2.9} %$ . The slope is consistent with the low acceleration limit of the RAR in galaxies, $g_{tot} = g_{†} g_{bar}$ , whereas the intercept implies a much higher acceleration scale of $g_{‡} = (2.02 \pm 0.11) \times 1 0^{- 9}$ ms $^{- 2}$ , indicating that there is no universal RAR that holds on all scales from galaxies to clusters. We find that the observed RAR in CLASH clusters is consistent with predictions from a semi-analytical model developed in the standard $Λ$ CDM framework. Our results also predict the presence of a baryonic Faber--Jackson relation ( $σ_{v}^{4} \propto M_{bar}$ ) on cluster scales.

Version accepted by ApJ. Textual changes to improve clarity. Semi-analytical model predictions improved (Figures 3, 4, and 5), better agreement with data. Results and conclusions unchanged

The Radial Acceleration Relation in CLASH Galaxy Clusters

Abstract

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