HST Observations within the Sphere of Influence of the Powerful Supermassive Black Hole in PKS0745-191

TL;DR

This study uses HST observations to map gas dynamics near a supermassive black hole in PKS0745-191, revealing chaotic flows and a massive black hole, shedding light on galaxy evolution and feedback processes.

Contribution

First spatially resolved map of gas dynamics within a SMBH's sphere of influence under powerful AGN feedback, showing chaotic flows and implications for self-regulating feedback loops.

Findings

Chaotic, non-rotational ionized gas flows on sub-kpc scales.

Detection of a very massive SMBH (~1.5×10^{10} M_sun).

Flat ionized gas density profile similar to X-ray gas around galaxies.

Abstract

We present Space Telescope Imaging Spectrograph observations from the Hubble Space Telescope of the supermassive black hole (SMBH) at the center of PKS0745-191, a brightest cluster galaxy (BCG) undergoing powerful radio-mode AGN feedback ($P_{\rm cav}\sim5\times10^{45}$ erg s$^{-1}$). These high-resolution data offer the first spatially resolved map of gas dynamics within a SMBHs sphere of influence under such powerful feedback. Our results reveal the presence of highly chaotic, non-rotational ionized gas flows on sub-kpc scales, in contrast to the more coherent flows observed on larger scales. While radio-mode feedback effectively thermalizes hot gas in galaxy clusters on kiloparsec scales, within the core, the hot gas flow may decouple, leading to a reduction in angular momentum and supplying ionized gas through cooling, which could enhance accretion onto the SMBH. This process could, in turn, lead to a self-regulating feedback loop. Compared to other BCGs with weaker radio-mode feedback, where rotation is more stable, intense feedback may lead to more chaotic flows, indicating a stronger coupling between jet activity and gas dynamics. Additionally, we observe a sharp increase in velocity dispersion near the nucleus, consistent with a very massive $M_{\rm BH}\sim1.5\times10^{10} M_\odot$ SMBH. The density profile of the ionized gas is also notably flat, paralleling the profiles observed in X-ray gas around galaxies where the Bondi radius is resolved. These results provide valuable insights into the complex mechanisms driving galaxy evolution, highlighting the intricate relationship between SMBH fueling and AGN feedback within the host galaxy.