A 40 Billion Solar-mass Black Hole in the Extreme Core of Holm 15A, the Central Galaxy of Abell 85

Abstract

Holm 15A, the brightest cluster galaxy (BCG) of the cool-core cluster Abell 85, has an ultra-diffuse central region, ∼ 2 mag fainter than the faintest depleted core of any early-type galaxy (ETG) that has been dynamically modelled in detail. New photometric data taken at the Wendelstein observatory confirm the previously noted unusual, near-exponential light profile of the galaxy's core. We use orbit-based, axisymmetric Schwarzschild models to analyse the stellar kinematics of Holm 15A from new high-resolution, wide-field spectral observations obtained with MUSE at the VLT. We find a supermassive black hole (SMBH) with a mass of (4.0 ± 0.80) × 10 10 M at the center of Holm 15A. This is the most massive black hole with a direct dynamical detection in the local universe. We find that the distribution of stellar orbits is increasingly biased towards tangential motions inside the core. However, the tangential bias is less than in other cored elliptical galaxies. We compare Holm 15A with N-body simulations of mergers between galaxies with black holes and find that the observed amount of tangential anisotropy and the shape of the light profile are consistent with a formation scenario where Holm 15A is the remnant of a merger between two ETGs with pre-existing depleted cores. We find that black hole masses in cored galaxies, including Holm 15A, scale inversely with the central stellar surface brightness and mass density, respectively. These correlation are independent of a specific parameterization of the light profile.

World-Universe Model—Alternative to Big Bang Model

“…According to WUM, Macrostructures of the World (Superclusters, Galaxies, [36]. The calculated maximum mass of galaxy Core of 6 × 10 10 solar masses (see Table 2) is in good agreement with the experimentally found value [36].…”

Dark Matter Cosmology and Astrophysics

“…According to WUM, Macrostructures of the World (Superclusters, Galaxies, Journal of High Energy Physics, Gravitation and Cosmology outer shells are larger and consist of lighter particles [11]. Table 1 Table 1) is in good agreement with the experimentally found value [60].…”

Coevolution (or not) of supermassive black holes and host galaxies: Black hole scaling relations are not biased by selection effects

“…Returning to astrophysical conclusions: Figure 3 adds the biggest BH discovered so far in the nearby Universe, M • = (4.0 ± 0.8) × 10 10 M in Holm 15A, the giant elliptical with the largest known core (Mehrgan et al 2019). It extends the M • -L K,bulge correlation toward larger luminosities and strengthens an important conclusion that has become evident as we find more giant BHs.…”

“…To further address possible bias in deriving BH -host correlations, I add six new BH mass measurements to Figure 3, five of them reported at this meeting. They are identified in the key; NGC 1380 (Tsukui 2019); NGC 383, NGC 404, and NGC 4697 (Bureau 2019), NGC 6958 (Thater 2019), and Holm 15A (Mehrgan et al 2019).…”