The impact of supermassive black holes on exoplanet habitability: I. Spanning the natural mass range
By Jourdan Waas, Eric S. Perlman, Manasvi Lingam, Emily Lohmann, Jackson Kernan, Francesco Tombesi, Amadeo Balbi, Alessandra Ambrifi
DOI https://doi.org/10.48550/arXiv.2511.10794
Abstract
While the influence of supermassive black hole (SMBH) activity on habitability has garnered attention, the specific effects of active galactic nuclei (AGN)winds, particularly ultra fast 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 (~100%) occurring across galactic scales for SMBHs ≥10^8 M ⊙ 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.
Introduction
In this study, the authors explore the influence of supermassive black holes (SMBHs) on the habitable conditions of exoplanets. Although the effects of active galactic nuclei (AGN) on habitability have been studied, the specific impact of winds produced by these black holes, particularly ultrafast outflows (UFOs), has received little attention.
Background
- SMBHs can range significantly in mass, influencing the energy output and wind properties, which in turn affect planetary atmospheres.
- Previous studies have generally focused on SMBHs in the Milky Way, particularly Sagittarius A*, but this does not capture the full spectrum of SMBH activities across galaxies.
- Understanding the impact of SMBH mass and distance from the center on exoplanetary habitability can provide insights into potential life-supporting environments in the universe.
Findings
Methods
The study uses simplified models to analyze how various factors (like the SMBH mass and distance from the black hole) influence exoplanet atmospheres. The relationship is explored through parameters such as:
- Atmospheric heating: Higher SMBH mass leads to increased atmospheric temperatures.
- Atmospheric escape: More significant SMBH mass correlates with higher rates of atmospheric loss; energy-driven winds are particularly impactful.
- Ozone depletion: The study highlights that ozone depletion increases with SMBH mass and decreases with distance from the black hole.
The paper adapts previous models, applying them to various SMBH masses to assess atmospheric heating, molecular thermal velocities, and ozone depletion.
Key Results
- Atmospheric Heating:
- Larger SMBHs lead to a significant increase in atmospheric temperatures at shorter distances from the galactic center.
- For instance, energy-driven winds cause much higher atmospheric heating than momentum-driven winds, particularly in the inner regions of galaxies.
- Atmospheric Escape:
- Atmospheric loss becomes more significant with increasing SMBH mass, particularly in energy-driven wind scenarios, which cause molecular velocities to exceed the escape velocity of the planet’s atmosphere.
- Ozone layer diminishment was closely associated with high-energy wind scenarios.
- Ozone Depletion:
- More massive SMBHs produce stronger winds that lead to greater nitrogen oxide (NOx) production, causing extensive ozone depletion. For instance, nearly 100% ozone depletion can occur near masses of 10^8 solar masses at distances of about 1 kiloparsec from the SMBH.
- The results indicate that substantial losses in ozone can severely undermine planetary habitability, particularly in the vicinity of large black holes.
- Extensional Habitability:
- The study suggests that the influence of AGN activity extends beyond immediate galactic centers, potentially affecting habitability in the outer regions of galaxies.
Conclusion
The authors conclude that the mass of a supermassive black hole at the center of a galaxy significantly impacts the habitability of exoplanets. They emphasize that as SMBH mass increases, it can enhance atmospheric heating, accelerate molecular escape, and cause extensive ozone depletion, particularly in energy-driven wind scenarios. The implications stretch across cosmic timelines, suggesting that SMBH growth has led to varying impacts on galactic habitability depending on mass and planetary system location.
Relevance
This work opens avenues for future research, suggesting that exploring AGN environments beyond our galaxy is crucial for understanding life-sustaining conditions in the universe. The findings underscore the importance of AGN dynamics in planetary atmospheres and their potential to influence the search for extraterrestrial life.