Cosmological Effects of the First Stars: Evolving Spectra of Population III

Abstract

The first stars hold intrinsic interest for their uniqueness and for their potential importance to galaxy formation, chemical enrichment, and feedback on the intergalactic medium (IGM). The metal-free composition of the first stars restricts the stellar energy source to proton-proton burning rather than the more efficient CNO cycle. Consequently they are hotter, smaller, and have harder spectra than their present-day counterparts of finite metallicity. We present new results from a continuing study of metal-free stars from a cosmological point of view. We have calculated evolving spectra of Pop III clusters, derived from a grid of zero-metallicity stellar evolutionary tracks. We find that H-ionizing photon production from metal-free stellar clusters takes twice as long as that of Pop II to decline to 1/10 its peak value. In addition, metal-free stars produce substantially more photons than Pop II in the HeII ($E>4$ Ryd) continuum. We suggest that large Ly$\alpha$ equivalent widths ($W_{\mathrm{Ly}\alpha }>400$ Angstroms) may provide a means of detecting metal-free stellar populations at high redshift, and that HeII recombination lines ($\lambda$1640, $\lambda$4686) may confirm identifications of Population III. While Pop III clusters are intrinsically bluer than their Pop II counterparts, nebular continuum emission makes up this difference and may confuse attempts to discern Pop III stars with broadband colors. In a companion paper, we explore the consequences of evolving spectra of Pop III for the reionization of the IGM in both H and He. (ABRIDGED)

Accepted by ApJ; 32 pages, 10 figures, with an updated discussion of the effects of mass loss on Pop III and Pop II comparisons. For full-resolution color figures, see http://casa.colorado.edu/~tumlinso/fs.html

References in corpus (9)

• The First Stars
• Evolution of the Ionizing Background and the Epoch of Reionization from the Spectra of z~6 Quasars
• Large Equivalent width Lyman-alpha line emission at z=4.5: young galaxies in a young universe
• Line-driven winds, ionizing fluxes and UV-spectra of hot stars at extremely low metallicity. I. Very massive O-stars
• A Redshift z = 6.56 Galaxy Behind the Cluster Abell 370
• The Detectability of High Redshift Lyman Alpha Emission Lines Prior to the Reionization of the Universe
• Structure, Evolution and Nucleosynthesis of Primordial Stars
• The Star Formation Rate Intensity Distribution Function--Implications for the Cosmic Star Formation Rate History of the Universe
• Evolving Spectra of Pop III Stars: Consequences for Cosmological Reionization

Cited by in corpus (59)

• Cosmology at Low Frequencies: The 21 cm Transition and the High-Redshift Universe
• The First Stars
• The observed ionization rate of the intergalactic medium and the ionizing emissivity at z >5: Evidence for a photon starved and extended epoch of reionization
• The First Cosmic Structures and their Effects
• The spectral evolution of the first galaxies. I. James Webb Space Telescope detection limits and color criteria for population III galaxies
• The First Galaxies: Assembly, Cooling and the Onset of Turbulence
• The Detectability of the First Stars and Their Cluster Enrichment Signatures
• Chemical Evolution in Hierarchical Models of Cosmic Structure II: The Formation of the Milky Way Stellar Halo and the Distribution of the Oldest Stars
• Chemical Evolution in Hierarchical Models Of Cosmic Structure I: Constraints on the Early Stellar Initial Mass Function
• Two populations of metal-free stars in the early Universe
• The Era of Massive Population III Stars: Cosmological Implications and Self-Termination
• Evolution in the properties of Lyman-alpha emitters from redshifts z ~ 3 to z ~ 2
• Discovery of an Enormous Ly$\alpha$ nebula in a massive galaxy overdensity at $z=2.3$
• Critical Metallicity and Fine-Structure Emission of Primordial Gas Enriched by the First Stars
• Spectroscopic Properties of the z=4.5 Lyman-alpha Emitters
• Cosmic Infrared Background and Early Galaxy Evolution
• Nucleosynthesis, Reionization, and the Mass Function of the First Stars
• First Star Signature in Infrared Background Anisotropies
• On the (non-)enhancement of the Lyman α equivalent width by a multiphase interstellar medium
• Metal-Free Gas Supply at the Edge of Reionization: Late-Epoch Population III Star Formation
• Decoding the X-ray Properties of Pre-Reionization Era Sources
• Galaxy Formation Spanning Cosmic History
• Detecting Population III stars through observations of near-IR cosmic infrared background anisotropies
• Evolving Spectra of Pop III Stars: Consequences for Cosmological Reionization
• The Epoch of Reionization in Models with Reduced Small Scale Power
• Probing Galaxy Formation with He II Cooling Lines
• Feedback From the First Supernovae in Protogalaxies:The Fate of the Generated Metals
• A photometric survey for Lyalpha-HeII dual emitters: Searching for Population III stars in high-redshift galaxies
• A Ly-alpha Emitter with an Extremely Large Rest-frame Equivalent Width of ~900A at z=6.5: A Candidate of Population III-dominated Galaxy?
• Exploring HeII$\lambda$1640 emission line properties at $z\sim 2-4$
• The nature of z ~ 2.3 Lyman-alpha emitters
• Star Formation at the Twilight of the Dark Ages: Which Stars Reionized the Universe?
• Very Massive Stars in High-Redshift Galaxies
• The Ionizing Efficiency of the First Stars
• Characterization of Population III Stars with Stellar Atmosphere and Evolutionary Modeling and Predictions of their Observability with the James Webb Space Telescope
• Ly-alpha emitting galaxies at redshift z~4.5 in the LALA Cetus field
• First stars and the extragalactic background light: How recent gamma-ray observations constrain the early universe
• A Faint Flux-Limited Lyman Alpha Emitter Sample at $z\sim 0.3$
• Probing Population III Stars in Galaxy IOK-1 at z = 6.96 through He II Emission
• An Observational Pursuit for Population III Stars in a Ly_alpha Emitter at z=6.33 through HeII Emission
• Narrow-band surveys for very high redshift Lyman-alpha emitters
• The Escape Fraction of Ionizing Radiation from Galaxies
• Cosmic Renaissance: The First Sources of Light
• Radiation-induced large-scale structure during the reionization epoch: the autocorrelation function
• The Radiative Transport of Dust in Primordial Galaxies and Second-Generation Star Formation
• High-redshift Ly alpha emitters with a large equivalent width: Properties of i-dropout galaxies with an NB921-band depression in the Subaru Deep Field
• Impacts of Dark Stars on Reionization and Signatures in the Cosmic Microwave Background
• Extended and Filamentary Lyman Alpha Emission from the Formation of a Protogalactic Halo at z=2.63
• X-rays and hard UV radiation From the First Galaxies: Ionization Bubbles and 21 cm Observations
• Single and binary evolution of Population III stars and their supernovae light curves
• On the population of primordial star clusters in the presence of UV background radiation
• Reionization in the Light of Dark Stars
• A Cosmic Milestone: Constraints from Metal-Poor Halo Stars on the Cosmological Reionization Epoch
• First Stars. I. Evolution without mass loss
• Detecting Primordial Stars
• Detecting the Transition From Pop III to Pop II Stars
• Implications of the cosmic infrared background excess for the cosmic star formation
• Challenges in Stellar Population Studies
• Star Forming Galaxies at z > 5