Related papers: Seeding the Second Star: enrichment from populatio…
We present a new self-consistent semi-analytic model of the first stars and galaxies to explore the high-redshift ($z{>}15$) Population III (PopIII) and metal-enriched star formation histories. Our model includes the detailed merger history…
The nature of the first massive stars may be inferred by investigating the origin of the extremely metal-poor (EMP) stars, likely formed from the ejecta of one or a few previous massive stars. We investigate the rotational properties of…
We aim to provide the first data-constrained estimate of the metal-free (Population III; Pop III) star formation rate density $\dot{\rho}_{*}^{III}$ required at high-redshifts ($z \gtrsim 16$) in order to reproduce both the amplitude and…
We utilize cosmological hydrodynamic simulations to study the formation of Population III (Pop III) stars in dark matter halos exposed to strong ionizing radiation. We simulate the formation of three halos subjected to a wide range of…
The stellar population in the Galactic halo is characterised by a large fraction of CEMP stars. Most CEMP stars are enriched in $s$-elements (CEMP-$s$ stars), and some of these are also enriched in $r$-elements (CEMP-$s/r$ stars). One…
We report the discovery of one extremely metal-poor (EMP; [Fe/H]<-3) and one ultra metal-poor (UMP; [Fe/H]<-4) star selected from the SDSS/SEGUE survey. These stars were identified as EMP candidates based on their medium-resolution…
The first stars are assumed to be predominantly massive. Although, due to the low initial abundances of heavy elements the line-driven stellar winds are supposed to be inefficient in the first stars, these stars may loose a significant…
The formation of the first stars (Population III; PopIII) marks the end of the dark ages of the universe, a subject of lively scientific debate. Not (yet) accessible to direct observations, this early stage of the universe is mostly studied…
The origin of Carbon Enhanced Metal-Poor (CEMP-no) stars with low abundances of neutron-capture elements is still unclear. These stars are ubiquitous, found primarily in the Milky Way halo and ultra-faint dwarf galaxies (UFDs). To make a…
Motivated by recent theoretical work suggesting that a substantial fraction of Population (Pop) III stars may have had masses low enough for them to survive to the present day, we consider the role that the accretion of metal-enriched gas…
As the Universe emerged from its initial hot and dense phase, its chemical composition was extremely simple, being limited to stable H and He isotopes, and traces of Li. The first stars that formed had such initial composition. However,…
We investigate the supernova explosions that end the lives of massive Population III stars in low-mass minihalos (M~10^6 M_sun) at redshifts z~20. Employing the smoothed particle hydrodynamics method, we carry out numerical simulations in a…
Population III (Pop III) stars are the first stars in the Universe, forming from pristine, metal-free gas and marking the end of the cosmic dark ages. Their formation rate is expected to sharply decline after redshift $z \approx 15$ due to…
I present a new Galactic chemical evolution model motivated by and grounded in the hierarchical theory of galaxy formation, as expressed by a halo merger history of the Galaxy. This model accurately reproduces the "metallicity distribution…
The first primitive galaxies formed from accretion and mergers by z ~ 15, and were primarily responsible for cosmological reionization and the chemical enrichment of the early cosmos. But a few of these galaxies may have formed in the…
The paper considers the evolution of the supernova envelopes produced by Population III stars with masses of $M_*\sim 25-200 M_\odot$ located in non-rotating protogalaxies with masses of $M\sim 10^7 M_\odot$ at redshifts $z=12$, with…
Two alternative scenarios concerning the origin and evolution of extremely metal-poor halo stars are investigated. The first one assumes that the stars have been completely metal-free initially and produced observed carbon and nitrogen…
We calculate cosmic distributions in space and time of the formation sites of the first, "Pop III.1" stars, exploring a model in which these are the progenitors of all supermassive black holes (SMBHs), seen in the centers of most large…
The advent of m class telescopes has allowed the detailed spectroscopic study of sizeable numbers of extremely metal-poor Galactic stars which are the witnesses of the formation of the early Galaxy. Their chemical composition displays some…
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…