First Light II: Emission Line Extinction, Population III Stars, and X-ray Binaries

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$\alpha$, the C IV $\lambda \lambda 1548,1551$ doublet, H-$\alpha$, and the Ca II $\lambda \lambda \lambda 8498,8542,8662$ 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$\alpha$ emission is discernible by $JWST$ as an increase in ${\mathrm{J}}_{200w}-{\mathrm{J}}_{277w}$ colour off the intrinsic stellar tracks. Observations of metal-free stars will be difficult, though not impossible, with the next generation of space telescopes.

19 pages, 14 figures, 1 table, submitted to MNRAS September 11, 2017, Published November 17, 2017

References in corpus (6)

• Theory of Star Formation
• The 2013 Release of Cloudy
• H-alpha Observations of a Large Sample of Galaxies at z~2: Implications for Star Formation in High Redshift Galaxies
• The Birth of a Galaxy. II. The Role of Radiation Pressure
• High Redshift Intergalactic C IV Abundance Measurements from the Near-Infrared Spectra of Two z~6 QSOs
• Heating the IGM by X-rays from Population III Binaries in High Redshift Galaxies

Cited by in corpus (5)

• UV absorption lines and their potential for tracing the Lyman continuum escape fraction
• Implications of inhomogeneous metal mixing for stellar archaeology
• Unveiling the contribution of Pop III stars in primeval galaxies at redshift $\ge 6$
• Blue galaxies: modelling nebular He II emission in high redshift galaxies
• Spectral Energy Distribution of the First Galaxies: Contribution from Pre-Main-Sequence Stars