Spectral Signatures of Population III and Envelope-stripped Stars in Galaxies at the Epoch of Reionization

Abstract

While most simulations of the epoch of reionization have focused on single-stellar populations in star-forming dwarf galaxies, products of binary evolution are expected to significantly contribute to emissions of hydrogen-ionizing photons. Among these products are stripped stars (or helium stars), which have their envelopes stripped from interactions with binary companions, leaving an exposed helium core. Previous work has suggested these stripped stars can dominate the LyC photon output of high-redshift low luminosity galaxies. Other sources of hard radiation in the early universe include zero-metallicity Population III stars, which may have similar SED properties to galaxies with radiation dominated by stripped star emissions. Here, we use two metrics (the power-law exponent over wavelength intervals 240-500 Å, 600-900 Å, and 1200-2000 Å, and the ratio of total luminosity in FUV wavelengths to LyC wavelengths) to compare the SEDs of simulated galaxies with only single-stellar evolution, galaxies containing stripped stars, and galaxies containing Population III stars, with four different IMFs. We find that stripped stars significantly alter the SEDs in the LyC range of galaxies at the epoch of reionization. SEDs in galaxies with stripped stars present have lower power-law indices in the LyC range and lower FUV to LyC luminosity ratios. These differences in SEDs are present at all considered luminosities ($M_{UV}>-15$, AB system), and are most pronounced for lower luminosity galaxies. We also find that SEDs of galaxies with stripped stars and Pop III stars are distinct from each other for all tested IMFs.

16 pages, 9 figures. Accepted to ApJ

References in corpus (18)

• Modules for Experiments in Stellar Astrophysics (MESA)
• Binary interaction dominates the evolution of massive stars
• Binary Population and Spectral Synthesis Version 2.1: construction, observational verification and new results
• The High Angular Resolution Multiplicity of Massive Stars
• Escape fraction of ionizing photons during reionization: effects due to supernova feedback and runaway OB stars
• Rotational mixing in massive binaries: detached short-period systems
• The Tarantula Massive Binary Monitoring: I. Observational campaign and OB-type spectroscopic binaries
• The Universe at z>10: Predictions for JWST from the UniverseMachine DR1
• X-ray binaries as the origin of nebular HeII emission in low-metallicity star-forming galaxies
• Wolf-Rayet stars in the Small Magellanic Cloud: I. Analysis of the single WN stars
• The properties of He II 1640 emitters at z ~ 2.5-5 from the VANDELS survey
• High-mass X-ray binaries in nearby metal-poor galaxies: on the contribution to nebular HeII emission
• Driving classical Wolf-Rayet winds: A Γ- and Z-dependent mass-loss
• Properties of WNh stars in the Small Magellanic Cloud: evidence for homogeneous evolution
• The qWR star HD 45166. II. Fundamental stellar parameters and evidence of a latitude-dependent wind
• Self-consistent predictions for LIER-like emission lines from post-AGB stars
• Interpreting high [O III]/Hbeta ratios with maturing starbursts
• Delayed Photons from Binary Evolution Help Reionize the Universe

Cited by in corpus (5)

• Constraining the physical properties of the first lensed $z\sim 10-16$ galaxy candidates with JWST
• The First Billion Years in Seconds: An Effective Model for the 21-cm Signal with Population III Stars
• A CRASH simulation of the contribution of binary stars to the epoch of reionization
• Radiation magnetohydrodynamics simulations of Population III star formation during the Epoch of Reionization
• A method for statistical research on binary stars using radial velocities