Assessing the potential for liquid solvents from X-ray sources: considerations on bodies orbiting AGN

TL;DR

This study explores the potential presence of liquid solvents like water, ammonia, and methane inside bodies orbiting AGN, considering various surface compositions, sizes, and distances from the snowline, revealing conditions under which these solvents could exist in liquid form.

Contribution

It introduces a model combining X-ray spectra from Seyfert galaxies with thermal and surface composition models to assess liquid solvent stability on hypothetical bodies orbiting AGN.

Findings

Liquid solvents can exist under diverse parameters.

Temperature constrains liquid water; size and pressure constrain methane and ammonia.

Results depend more on body size and solvent properties than on AGN energy output.

Abstract

Aims. We aim to establish a rough first prospect on the potential of certain biorelevant solvents (water, ammonia and methane) to be present in liquid form inside the uppermost few meters of several modelled surfaces (rocky and icy crusts of various compositions) of hypothetical bodies orbiting active galactic nuclei (AGN), and investigate under which constraints this might occur. Methods. We adjust and average together X-ray spectra from a sample of 20 Type 1 Seyfert galaxies to calculate a mean snowline of the sample used. Based on this, we introduce variation of a hypothetical body's orbit across distances between 10% and 100% of the snowline radius, and calculate a sub-surface attenuation within four different model surface compositions for each. Surface compositions are based on lunar soil and solvent ices found in the milky way's circumnuclear region. We then use this as a continuous source term for a thermal model. Example bodies are systematically investigated with sizes between 1/30 and 20 earth radii. Further outlier variations are also considered (such as the case of bound rotation of the body) to end up with a perspective of solvent phases under a wide slew of many different conditions. Results. We find that liquid solvents are possible under a multitude of parameters, with temperature being the main constraint to liquid water and body size as well as pressure being the main constraint to liquid methane and ammonia. We further find that these results, when adjusted for snowline distance, depend less on the energy output of the central source within the Seyfert Type 1 AGN than on other parameters, such as body sizes and solvent properties.