相关论文: Cosmic Star Formation, Reionization, and Constrain…
We study the evolution of stellar content and the chemical enrichment of the universe averaged over the whole population of galaxies by means of a series of chemo-spectrophotometric models that take into account the metallicity and dust…
We use simple analytic reasoning to identify physical processes that drive the evolution of the cosmic star formation density in cold dark matter universes. Based on our analysis, we formulate a model to characterise the redshift dependence…
I use cosmological simulations that incorporate a physically motivated approximation to three-dimensional radiative transfer that recovers correct asymptotic ionization front propagation speeds for some cosmologically relevant density…
The protagonists of cosmic reionization remain elusive. Faint star-forming galaxies are leading candidates because they are numerous and may have significant ionizing photon escape fractions ($f_{esc}$). Here we update this picture via an…
We consider the present-day photometric and chemical properties of elliptical galaxies, adopting the bimodal star formation scenario of Elbaz, Arnaud & Vangioni-Flam (1995). These models utilise an initial mass function (IMF) biased heavily…
We calculate the evolution of Li6 generated from cosmic rays produced by an early population of massive stars. The computation is performed in the framework of hierarchical structure formation and is based on cosmic star formation histories…
We present first results from three-dimensional hydrodynamic simulations of the high redshift formation of dwarf galaxies. The simulations use an Eulerian adaptive mesh refinement technique to follow the non-equilibrium chemistry of…
We explore the onset of star formation in the early Universe, exploiting the observations of high-redshift Lyman-break galaxies (LBGs) and Lyman alpha emitters (LAEs), in the framework of the galaxy formation scenario elaborated by Granato…
We investigate the star formation and chemical evolution in the early universe by considering the merging history of the Galaxy in the {\Lambda}CDM scenario according to the extended Press-Schechter theory. We give some possible constraints…
Recent theoretical studies have revealed the possibly important role of the capture and annihilation process of weakly interacting massive particles (WIMPs) for the first stars. Using new evolutionary models of metal-free massive stars, we…
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…
We examine the dynamical evolution and statistical properties of the supernova ejecta of massive primordial stars in a cosmological framework to determine whether this first population of stars could have enriched the universe to the levels…
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,…
The first massive stars triggered the onset of chemical evolution by releasing the first metals (elements heavier than helium) in the Universe. The nature of these stars and how the early chemical enrichment took place is still largely…
We investigate the possibility that the Universe is reionized by the decay products of heavy particles. In particular we study under which circumstances this decay may produce a significant reionization at high redshift ($z \simeq 20$), as…
High-resolution numerical simulations including feedback and aimed at calculating the escape fraction (fesc) of hydrogen-ionizing photons often assume stellar radiation based on single-stellar population synthesis models. However, strong…
Standard analytical chemical evolution modelling of galaxies has been assuming the stellar initial mass function (IMF) to be invariant and fully sampled allowing fractions of massive stars to contribute even in dwarf galaxies with very low…
The recent discovery by Cowie \etal and Tytler \etal of metals in the \Lya clouds shows that the intergalactic medium (IGM) at high redshift is contaminated by the products of stars, and suggests that ionizing photons from massive star…
The Cosmic Dark Ages mark a pivotal era of the universe's evolution, transitioning from a neutral, opaque medium to the emergence of the first stars and galaxies that initiated cosmic reionization. This study examines the thermodynamics of…
Aims. A sample of early B-type stars in OB associations and the field within the solar neighbourhood is studied comprehensively. Present-day abundances for the astrophysically most interesting chemical elements are derived. Methods.…