The High-Mass End of the Black Hole Mass Function: Mass Estimates in Brightest Cluster Galaxies

TL;DR

This study uses Hubble Space Telescope data and dynamical modeling to measure supermassive black hole masses in three Brightest Cluster Galaxies, advancing understanding of the high-mass end of the black hole mass function.

Contribution

It provides new black hole mass measurements in three Brightest Cluster Galaxies using detailed imaging, spectroscopy, and dynamical models, improving high-mass black hole statistics.

Findings

Secure black hole mass detections for two galaxies.

Upper limit on black hole mass in the third galaxy.

Improved constraints on the high-mass end of the black hole mass function.

Abstract

We present Hubble Space Telescope imaging and spectroscopic observations of three Brightest Cluster Galaxies, Abell 1836-BCG, Abell 2052-BCG, and Abell 3565-BCG, obtained with the Wide Field and Planetary Camera 2, the Advanced Camera for Surveys and the Space Telescope Imaging Spectrograph. The data provide detailed information on the structure and mass profile of the stellar component, the dust optical depth, and the spatial distribution and kinematics of the ionized gas within the innermost region of each galaxy. Dynamical models, which account for the observed stellar mass profile and include the contribution of a central supermassive black hole (SBH), are constructed to reproduce the kinematics derived from the Halpha and [N II](lambda 6548,6583) emission lines. Secure SBH detection with M_bh=3.61(+0.41,-0.50)x10^9 M_sun and M_bh=1.34(+0.21,-0.19)x10^9 M_sun, respectively, are obtained for Abell 1836-BCG and Abell 3565-BCG, which show regular rotation curves and strong central velocity gradients. In the case of Abell 2052-BCG, the lack of an orderly rotational motion prevents a secure determination, although an upper limit of M_bh < 4.60x10^9 M_sun can be placed on the mass of the central SBH. These measurements represent an important step forward in the characterization of the high-mass end of the SBH mass function.