Revisiting the bimodality of galactic habitability in IllustrisTNG

TL;DR

This study reevaluates the link between galaxy properties and habitability using IllustrisTNG data, finding that galactic bimodality in habitability is less prominent and highlighting the potential of non-traditional galactic structures for hosting life.

Contribution

Refines previous analyses of galactic habitability by applying stricter criteria and exploring the role of tidal remnants and dense environments in supporting life.

Findings

Bimodality in galactic habitability is significantly reduced.

Metal-rich dwarf galaxies and tidal structures may enhance habitability.

Non-traditional galactic environments could be promising for astrobiology.

Abstract

The potential of galaxies to host habitable planets is central to astrobiology, tightly linked to galaxy-scale evolution and cosmological processes. Using IllustrisTNG, we revisit the proposed local peak in the mass-metallicity relation for small, metal-rich, star-forming galaxies (Cloudlet) as an indicator of enhanced galactic habitability. We refine the earlier analysis by applying updated filtering criteria to identify a more refined sample, further selecting objects based on their history. This process resulted in a confirmed sample of 97 dwarf galaxies, alongside 519 additional structures of uncertain origin, potentially comprising both numerical artefacts and unrecognised physical systems. Under these stricter conditions, the proposed bimodality in galactic habitability is strongly diminished. However, the astrobiological potential of metal-rich dwarfs, most of which are compact remnants of more massive galaxies that underwent tidal stripping, is a thrilling area of exploration. Although dense stellar environments are traditionally seen as inhospitable, recent studies highlight the role of dynamic environments in enhancing the distribution of biological material. Furthermore, the potential habitability of tidal structures formed in the aftermath of galactic interactions is a fascinating possibility. Our findings suggest that non-traditional structures support conditions favourable for life, opening up exciting new avenues for astrobiological research. This research underscores the need for a holistic approach to studying habitability that moves beyond planetary and stellar-focused frameworks to incorporate the broader galactic environment. Understanding the interactions between galaxies, their evolution, and the influence of their surroundings is essential to developing a more comprehensive model of how and where life might emerge and persist across the Universe.