A distinct radial acceleration relation across the brightest cluster galaxies and galaxy clusters

¹ Institute of Astronomy, National Central University, Taoyuan 320317, Taiwan
² Department of Physics and Center for Complex Systems, National Central University, Taoyuan 320317, Taiwan
e-mail: cmko@astro.ncu.edu.tw
³ Leibniz-Institute for Astrophysics, An der Sternwarte 16, 14482 Potsdam, Germany
⁴ Department of Astronomy, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, 44106 OH, USA
e-mail: stacy.mcgaugh@case.edu

Received: 4 September 2023
Accepted: 2 February 2024

Abstract

Recent studies reveal a radial acceleration relation (RAR) in galaxies, which illustrates a tight empirical correlation connecting the observational acceleration and the baryonic acceleration with a characteristic acceleration scale. However, a distinct RAR has been revealed on brightest cluster galaxy (BCG) cluster scales with a seventeen-times-larger acceleration scale due to the gravitational lensing effect. In this work, we systematically explore the acceleration and mass correlations between dynamical and baryonic components in 50 BCGs. To investigate the dynamical RAR in BCGs, we derived their dynamical accelerations from the stellar kinematics using the Jeans equation through Abel inversion and adopted the baryonic mass from Sloan Digital Sky Survey photometry. We explored the spatially resolved kinematic profiles with the largest integral field spectroscopy (IFS) data collected by the Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) survey. Our results demonstrate that the dynamical RAR in BCGs is consistent with the lensing RAR on BCG-cluster scales as well as a larger acceleration scale. This finding may imply that BCGs and galaxy clusters have fundamental differences from field galaxies. We also find a mass correlation, but it is less tight than the acceleration correlation.