"Grandeur in this view of life": N-body simulation models of the Galactic habitable zone

TL;DR

This study uses N-body simulations to model the distribution of habitable environments in a Milky Way-like galaxy, revealing that habitable zones tend to develop in the galaxy's outskirts over time.

Contribution

It introduces a novel simulation approach to map the evolution of habitable zones in a galaxy, highlighting their migration to outer regions over 10 Gyr.

Findings

Peak habitable stellar mass density shifts outward over time.

Most habitable stars are found beyond the Solar neighborhood.

Galactic civilizations may emerge in the galaxy's outskirts.

Abstract

We present an isolated Milky Way-like simulation in GADGET2 N-body SPH code. The Galactic disk star formation rate (SFR) surface densities and stellar mass indicative of Solar neighbourhood are used as thresholds to model the distribution of stellar mass in life friendly environments. SFR and stellar component density are calculated averaging the GADGET2 particle properties on a 2D grid mapped on the Galactic plane. The peak values for possibly habitable stellar mass surface density move from $10$ to $15$ kpc cylindrical galactocentric distance in $10$ Gyr simulated time span. At $10$ Gyr the simulation results imply the following. Stellar particles which have spent almost all of their life time in habitable friendly conditions reside typically at $\sim16$ kpc from Galactic centre and are $\sim 3$ Gyr old. Stellar particles that have spent $\ge 90 \%$ of their $4-5$ Gyr long life time in habitable friendly conditions, are also predominantly found in the outskirts of the Galactic disk. Less then $1 \%$ of these particles can be found at a typical Solar system galactocentric distance of $8-10$ kpc. Our results imply that the evolution of an isolated spiral galaxy is likely to result in galactic civilizations emerging at the outskirts of the galactic disk around stellar hosts younger than the Sun.