Related papers: Helium diffusion during formation of the first gal…
We model gas cooling in high-resolution N-body simulations in order to investigate the formation of the first generation of stars. We follow a region of a LCDM universe especially selected to contain a rich cluster by the present day. The…
The sun and giant planets are generally thought to have the same helium abundance as that in the solar nebula from which they were formed 4.6 billion years ago. In contrast, the interstellar medium reflects current galactic conditions. The…
Thermal and chemical evolution of primordial gas clouds irradiated with far-ultraviolet (FUV; < 13.6 eV) radiation is investigated. In clouds irradiated by intense FUV radiation, sufficient hydrogen molecules to be important for cooling are…
The first galaxies formed at high redshifts, and were likely substantially less massive than typical galaxies in the local universe. We argue that (1) the reionization of a clumpy intergalactic medium by redshift z=6, (2) its enrichment by…
The light relic density affects the thermal and expansion history of the early Universe leaving a number of observable imprints. We focus on the primordial abundances of light elements produced during the process of Big Bang nucleosynthesis…
We study the baryonic, chemical and dynamical properties of a significantly large sample of early proto-galaxies in the first 500 Myr of the Universe (redshift z>9), obtained from high-resolution numerical, N-body, hydrodynamical, chemistry…
Recent observations made using the James Webb Space Telescope have identified a number of high-redshift galaxies that are unexpectedly luminous. In light of this, it is clear that a more detailed understanding of the high redshift,…
This paper describes a new determination of the primordial helium abundance (Y_P), based on the abundance analysis of five metal-poor extragalactic HII regions. For three regions of the sample (SBS 0335-052, I Zw 18, and H29) we present…
Context. Globular clusters host stars with chemical peculiarities. The associated helium enrichment is expected to affect the evolution of stars, in general, and of low-mass stars, and in particular the progenitors of white dwarfs (WDs).…
It has been recently shown that the relative velocity between the dark matter and the baryons (vbc) at the time of recombination can affect the structure formation in the early universe (Tseliakhovich & Hirata 2010). We statistically…
The properties of the first galaxies are shaped in large part by the first generations of stars, which emit high energy radiation and unleash both large amounts of mechanical energy and the first heavy elements when they explode as…
We have derived a primordial helium abundance of Yp = 0.2477 +- 0.0029, based on new atomic physics computations of the recombination coefficients of He I and of the collisional excitation of the H I Balmer lines together with observations…
The impact of the streaming between baryons and dark matter on the first structures has been actively explored by recent studies. We investigate how the key results are affected by two popular approximations. One is to implement the…
We present a model for the formation of the first galaxies before and after the reionization of hydrogen in the early universe. In this model, galaxy formation can only take place in dark matter haloes whose mass exceeds a…
Turbulence plays a critical role in regulating star formation in molecular clouds and is also observed in simulations of primordial halos that host Population III (Pop III) stars. The relative velocity between baryons and dark matter at the…
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 first dark matter halos form by direct collapse from peaks in the matter density field, and evidence from numerical simulations and other analyses suggests that the dense inner regions of these objects largely persist today. These halos…
(abridged) We use a one-dimensional hydrodynamical code to investigate the effects of preheating on gas accretion and cooling in cold dark matter halos. In the absence of radiative cooling, preheating reduces the amount of gas that can be…
Observations of metal-poor extragalactic H II regions allow the determination of the primordial helium abundance, Y_p. The He I emissivities are the foundation of the model of the H II region's emission. Porter, Ferland, Storey, & Detisch…
First-generation (Population III) stars in the universe play an important role inearly enrichment of heavy elements in galaxies and intergalactic medium and thus affect the history of galaxies. The physical and chemical properties of…