相关论文: Where are the missing cosmic metals ?
A galaxy's metallicity provides a record of star formation, gas accretion, and gas outflow, and is therefore one of the most informative measurements that can be made at high redshift. It is also one of the most difficult. I review methods…
Lenticular galaxies remain remarkably mysterious as a class. Observations to date have not led to any broad consensus about their origins, properties and evolution, though they are often thought to have formed in one big burst of star…
The apparent absence of stars in the Milky Way halo with -5 ~< [Fe/H] ~< -4 suggests that the gas out of which the halo stars were born experienced a period of low or delayed star formation after the local universe was lit up by the first,…
Observations show that galaxies follow a mass-metallicity relation over a wide range of masses. One currently favoured explanation is that less massive galaxies are less able to retain the gas and stellar ejecta and thus may lose the…
We report on the surprisingly high metallicity measured in two absorption systems at high redshift, detected in the Very Large Telescope spectrum of the afterglow of the gamma-ray burst GRB 090323. The two systems, at redshift z=3.5673 and…
We explore the elemental abundance features of metal-rich disk stars, highlighting the comparisons made with those of the recently revealed Galactic bulge stars. A similarity between two of the comparisons leads to a new theoretical picture…
The early chemical evolution of the Galaxy and the Universe is vital to our understanding of a host of astrophysical phenomena. Since the most metal-poor Galactic stars (with metallicities down to [Fe/H]\sim-5.5) are relics from the…
We present semi-analytic models of galactic outflows, constrained by available observations on high redshift star formation and reionization. Galactic outflows are modeled in a manner akin to models of stellar wind blown bubbles. Large…
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 present the results of the largest survey to date for intergalactic metals at redshifts z > 5, using near-IR spectra of nine QSOs with emission redshifts z(em) > 5.7. We find, for the first time, a change in the comoving mass density of…
(Abridged) We use a combination of high resolution N-body simulations and semi-analytic techniques to follow the formation, the evolution and the chemical enrichment of cluster galaxies in a Lambda-CDM Universe. We model the transport of…
Li abundances in the bulk of low-mass metal-poor stars are well reproduced by stellar evolution models adopting a constant initial abundance. However, a small number of stars have exceptionally high Li abundances, for which no convincing…
The first metals in the universe are expected to form in population III stars - primordial stars consisting entirely of hydrogen and helium. However, these stars have so far remained elusive. Simulations indicate that galaxies consisting…
The chemical composition of stars with extremely low metal contents (taking ``metals'' to mean all elements other than hydrogen and helium) provides us with information on the masses of the stars that produced the first metals. Such a…
In order to understand galaxy evolution through cosmic times it is critical to derive the properties of the molecular gas content of galaxies, i.e. the material out of which stars ultimately form. The last decade has seen rapid progress in…
Star formation from metal-free gas, the hallmark of the first generation of Population III stars, was long assumed to occur only in the very early Universe. We report the discovery of MPG-CR3 (Metal-Pristine Galaxy COSMOS Redshift 3;…
The first stars form in dark matter halos of masses ~10^6 M_sun as suggested by an increasing number of numerical simulations. Radiation feedback from these stars expels most of the gas from their shallow potential well of their surrounding…
The evolution and explosion of metal-free stars with masses 10--100 solar masses are followed, and their nucleosynthetic yields, light curves, and remnant masses determined. When the supernova yields are integrated over a Salpeter initial…
We explore the predictions of the standard hierarchical clustering scenario of galaxy formation, regarding the numbers and metallicities of PopIII stars likely to be found within our Galaxy today. By PopIII we shall be referring to stars…
Magnitude-limited galaxy redshift surveys are now providing large samples of galaxies to beyond z=2, while color-selected and emission-line-selected samples are finding galaxies to z=4.7. A broad picture is emerging of galaxy formation…