Related papers: Transition From Population III to Population II St…
A PopIII/Pop II transition from massive to normal stars is predicted to occur when the metallicity of the star forming gas crosses the critical range Z_cr = 10^(-5 +/- 1) Z_sun. To investigate the cosmic implications of such process we use…
We discuss the cosmological significance of the transition from the Pop III to Pop II mode of star formation in the early universe, and when and how it may occur in primordial galaxies. Observations that could detect this transition include…
We investigate the transition from primordial Population III (Pop III) star formation to normal Pop II star formation in the first galaxies using new cosmological hydrodynamic simulations. We find that while the first stars seed their host…
There are only a few ways to constrain the Era of Reionization and the properties of high redshift (z>6) stars through observations. Here, we discuss one of these observables - the spectrum of the Near Infrared Background - and how it is…
In an earlier paper (Cen 2003) we pointed out the strong likelihood for the universal reionization to occur twice, giving rise to a larger Thomson optical depth. Here we perform a more focused analysis of the Thomson optical depth in light…
New observations from the Hubble ultra deep field suggest that the star formation rate at z>7 drops off faster than previously thought. Using a newly determined star formation rate for the normal mode of Population II/I stars (PopII/I),…
We combine fast radiative transfer calculations with high resolution hydrodynamical simulations to study an epoch of early hydrogen reionisation by primordial stellar sources at redshifts 15<z<30. With relatively conservative assumptions,…
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 investigate the impact of an early population of massive stars on their surroundings. Dissociation of molecular hydrogen by strong UV emission from such stars is expected to produce a global transition in the cooling mechanism of…
We study the observational consequences of several unknown properties of Population III (Pop III) stars using large-scale cosmological simulations that include a subgrid model to track the unresolved mixing of pollutants. Varying the value…
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…
Motivated by theoretical predictions that first stars were predominantly very massive, we investigate the physics of the transition from an early epoch dominated by massive Pop III stars to a later epoch dominated by familiar low-mass Pop…
Recent studies have highlighted that galaxies at z = 6-8 fall short of producing enough ionizing photons to reionize the IGM, and suggest that Population III stars could resolve this tension, because their harder spectra can produce ~10x…
Cosmological simulations of Population III star formation suggest an initial mass function (IMF) biased toward very massive stars (M>100Msun) formed in minihalos at redshift z>20, when the cooling is driven by molecular hydrogen. However,…
Population III stars, the first generation of stars formed from primordial Big Bang material with a top-heavy IMF, should contribute substantially to the Universe reionization and they are crucial for understanding the early metal…
Population III star formation during the dark ages shifted from minihalos (~10^6 Msun) cooled via molecular hydrogen to more massive halos (~10^8 Msun) cooled via Ly-alpha as Lyman-Werner backgrounds progressively quenched molecular…
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…
Using varying models for the star formation rate (SFR) of Population (Pop) III and II stars at z>6 we derive the expected redshift history of the global 21 cm signal from the inter-galactic medium (IGM). To recover the observed Thomson…
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…
Population-III (Pop-III) starformation (SF) is thought to be quenched when the metallicity of the star-forming gas reaches a critical level. At high z, when the general intergalactic medium (IGM) was enriched with metals, the fraction of…