The Impact of Supermassive Black Holes on Exoplanet Habitability. I. Spanning the Natural Mass Range

TL;DR

This paper investigates how supermassive black holes influence exoplanet habitability, focusing on atmospheric effects and ozone depletion related to SMBH mass and galactic position.

Contribution

It introduces simplified models linking SMBH mass to planetary atmospheric heating, ozone depletion, and habitability across galactic scales.

Findings

Higher SMBH mass increases atmospheric heating and ozone depletion.

Energy-driven winds have a stronger impact than momentum-driven winds.

Nearly complete ozone loss occurs for SMBH masses ≥10^8 M_sun at galactic centers.

Abstract

While the influence of supermassive black hole (SMBH) activity on habitability has garnered attention, the specific effects of active galactic nucleus (AGN) winds, particularly ultrafast outflows (UFOs), on planetary atmospheres remain largely unexplored. This study aims to fill this gap by investigating the relationship between SMBH mass at the galactic center and exoplanetary habitability, given that SMBH masses are empirically confirmed to span approximately 5 orders of magnitude in galaxies. Through simplified models, we account for various results involving the relationships between the distance from the planet to the central SMBH and the mass of the SMBH. Specifically, we show that increased SMBH mass leads to higher atmospheric heating and elevated temperatures, greater molecular thermal velocities, and enhanced mass loss, all of which diminish with distance from the galactic center. Energy-driven winds consistently have a stronger impact than momentum-driven ones. Crucially, ozone depletion is shown to rise with SMBH mass and decrease with distance from the galactic center, with nearly complete ozone loss ($\sim100\%$) occurring across galactic scales for SMBH masses $\geq 10^8 M_\odot$ in the energy-driven case. This study emphasizes that SMBH growth over cosmic time may have produced markedly different impacts on galactic habitability, depending on both the mass of the central black hole (BH) and the location of planetary systems within their host galaxies.