相关论文: Zero metallicity stellar sources and the reionizat…

We present stellar structure and atmosphere models of metal-free stars and examine them from a cosmological point of view. Metal-free stars exhibit high effective temperatures and small sizes relative to metal-enriched stars of equal mass.…

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…

[abridged] The First Stars in the Universe form out of pristine primordial gas clouds that have been radiatively cooled to a few hundreds of degrees Kelvin either via molecular or atomic (Lyman-Alpha) hydrogen lines. This primordial mode of…

The birth and death of the first generation of stars have important implications for the thermal state and chemical properties of the intergalactic medium (IGM) in the early universe. Sometime after recombination, the neutral, chemically…

The first stars are thought to be one of the dominant sources of hydrogen reionization in the early Universe, with their high luminosities and surface temperatures expected to drive high ionizing photon production rates. In this work, we…

We investigate whether a single population of first stars could have influenced both the metal enrichment and reionization of the high-redshift intergalactic medium (IGM), by calculating the generated ionizing radiation per unit metal yield…

We simulate a plausible cosmological model in considerable physical and numerical detail through the successive phases of reheating (at 10<z<20), formation of Pop III stars at z=15 (due to molecular hydrogen cooling), with subsequent…

We present results from the first cosmological simulations which study the onset of primordial, metal-free (population III), cosmic star formation and the transition to the present-day, metal-rich star formation (population II-I), including…

We construct star formation histories at redshifts z > 5 for two physically distinct populations of primordial, metal-free stars, motivated by theoretical and observational arguments that have hinted towards the existence of an intermediate…

We calculate the reionization history for different models of the stellar population and explore the effects of primordial magnetic fields, dark matter decay and dark matter annihilation on reionization. We find that stellar populations…

By definition, Population III stars are metal-free, and their protostellar collapse is driven by molecular hydrogen cooling in the gas-phase, leading to large characteristic masses. Population II stars with lower characteristic masses form…

We present extensive evolutionary models of stars with initial zero-metallicity, covering a large range of initial masses (i.e. 0.7 <= M <= 100 Msun). Calculations are carried out at constant mass, with updated input physics, and applying…

We estimate the maximum contribution to reionization from the first generation of massive stars, with zero metallicity, under the assumption that one of these stars forms with a fixed mass in every collapsed halo in which metal-free gas is…

All stellar evolution models for nucleosynthesis require an initial isotopic abundance set to use as a starting point. Generally, our knowledge of isotopic abundances of stars is fairly incomplete except for the Solar System. We present a…

Motivated by the recent detection of metals in different components of the high redshift universe and by the abundance ratios measured in the extremely metal-poor stars of our Galaxy, we study the nucleosynthesis constraints that this…

Motivated by the WMAP results indicating an early epoch of reionization, we consider alternative cosmic star formation models which are capable of reionizing the early intergalactic medium. We develop models which include an early burst of…

We present new evolutionary models for zero-metallicity stars, covering a large range of initial masses (from 0.8 to 100 M_sun). Models are computed with overshooting from stellar cores and convective envelopes, and assuming mass-loss from…

Metallicity is one of the crucial factors that determine stellar evolution. To characterize the properties of stellar populations one needs to know the fraction of stars forming at different metallicities. Knowing how this fraction evolves…

The relationship between stellar populations and the ionizing flux with which they irradiate their surroundings has profound implications for the evolution of the intergalactic medium. We quantify the ionizing flux arising from synthetic…

The epoch of reionization and formation of first stars are inter-linked topics that are of considerable interest. We use a simplified approach for studying formation of stars in collapsed haloes, and the resulting ionization of the…