First light – II. Emission line extinction, population III stars, and X-ray binaries

• Published in: Monthly notices of the Royal Astronomical Society Vol. 474; no. 2; pp. 2617 - 2634
• Main Authors: Barrow, Kirk S S, Wise, John H, Aykutalp, Aycin, O'Shea, Brian W, Norman, Michael L, Xu, Hao
• Format: Journal Article
• Language: English
• Published: London Oxford University Press 21.02.2018
• Subjects: Binary stars; Computer simulation; Emission; Extinction; Far infrared radiation; Galaxies; High energy astronomy; Interstellar; Metals; Photometry; Photons; Population III stars; Red shift; Space telescopes; Star & galaxy formation; Stellar populations; Telescopes; X ray binaries; X ray stars; stars: Population III; X-rays: binaries; techniques: photometric; techniques: spectroscopic; galaxies: high-redshift; dark ages, reionization, first stars
• ISSN: 0035-8711; 1365-2966
• DOI: 10.1093/mnras/stx2973

Abstract We produce synthetic spectra and observations for metal-free stellar populations and high-mass X-ray binaries in the Renaissance Simulations at a redshift of 15. We extend our methodology from the first paper in the series by modelling the production and extinction of emission lines throughout a dusty and metal-enriched interstellar and circum-galactic media extracted from the simulation, using a Monte Carlo calculation. To capture the impact of high-energy photons, we include all frequencies from hard X-ray to far-infrared with enough frequency resolution to discern line emission and absorption profiles. The most common lines in our sample in order of their rate of occurrence are Ly α, the C iv λλ1548, 1551 doublet, H α, and the Ca ii λλλ8498, 8542, 8662 triplet. The best scenario for a direct observation of a metal-free stellar population is a merger between two Population III Galaxies. In mergers between metal-enriched and metal-free stellar populations, some characteristics may be inferred indirectly. Single Population III galaxies are too dim to be observed photometrically at z = 15. Ly α emission is discernible by JWST as an increase in J200w − J277w colour off the intrinsic stellar tracks. Observations of metal-free stars will be difficult, though not impossible, with the next generation of space telescopes.