Tetrahedral hydrocarbon nanoparticles in space: X-ray spectra

TL;DR

This paper uses density functional theory to calculate X-ray spectra of tetrahedral nanodiamonds, proposing their potential detection in space with future high-resolution X-ray telescopes like Arcus.

Contribution

It provides the first theoretical X-ray absorption spectra of large nanodiamonds and assesses their detectability in the interstellar medium with upcoming telescopes.

Findings

Nanodiamonds have distinct X-ray spectral features.

Simulated spectra suggest detectability with Arcus.

Method validated on small C-H tetrahedral molecule.

Abstract

It has been proposed, or confirmed, that diamond nanoparticles exist in various environments in space: close to active galactic nuclei, in the vicinity of supernovae and pulsars, in the interior of several planets in the Solar system, in carbon planets and other exoplanets, carbon-rich stars, meteorites, in X-ray active Herbig Ae/Be stars, and in the interstellar medium. Using density functional theory methods we calculate the carbon K-edge X-ray absorption spectrum of two large tetrahedral nanodiamonds: C26H32 and C51H52. We also study and test our methods on the astrophysical molecule CH4, the smallest C-H tetrahedral structure. A possible detection of nanodiamonds from X-ray spectra by future telescopes, such as the project Arcus, is proposed. Simulated spectra of the diffuse interstellar medium using Cyg X-2 as a source show that nanodiamonds studied in this work can be detected by Arcus, a high resolution X-ray spectrometer mission selected by NASA for a Phase A concept study.