相关论文: Formation of the First Stars and Quasars
We study the observational signatures of a potential population of low-luminosity quasars at high redshifts in a LambdaCDM cosmology. We derive the evolution of the quasar luminosity function at fainter luminosities and higher redshifts…
The transition between the nearly smooth initial state of the Universe and its clumpy state today occurred during the epoch when the first stars and low-luminosity quasars formed. For Cold Dark Matter cosmologies, the radiation produced by…
This work studies the connection between the first galaxies and their hosting dark matter halos in the early Universe when Reionization is concluding. Our numerical models (already presented in an earlier study) trace the star formation…
Quasars are among the most luminous objects in the universe, and they can be studied in detail up to the highest known redshift. Assuming that the gas associated with quasars is closely related to the interstellar medium of the host galaxy,…
Studies of the formation of the first stars have established that they formed in small halos of $\sim 10^5 - 10^6 M_{\odot}$ via molecular hydrogen cooling. Since a low level of ultraviolet radiation from stars suffices to dissociate…
We calculate the observable signatures of the first generation of stars at high redshift (5<z<100). To determine the cosmic star-formation history, we use an extension of the Press-Schechter formalism for Cold Dark Matter (CDM) cosmologies…
The first generation of stars produces a background of Lyman-Werner (LW) radiation which can photo-dissociate molecular hydrogen, increasing the mass of dark matter halos required to host star formation. Previous studies have determined the…
The formation of the first generations of stars at redshifts z > 15-20 signaled the transition from the simple initial state of the universe to one of increasing complexity. We here review recent progress in understanding the assembly…
We review recent theoretical results on the formation of the first stars and quasars in the universe, and emphasize related open questions. In particular, we list important differences between the star formation process at high redshifts…
Dark and baryonic matter moved at different velocities in the early Universe, which strongly suppressed star formation in some regions. This was estimated to imprint a large-scale fluctuation signal of about 2 mK in the 21-cm spectral line…
We use a spherical hydrodynamics code to show that in cold dark matter cosmologies, the first stars form at z=50 through the direct collapse of gas in low-mass systems (approx 10^4 solar masses). Photons from the first stars easily…
I review recent progress in understanding the formation of the first stars and quasars. The initial conditions for their emergence are given by the now firmly established model of cosmological structure formation. Numerical simulations of…
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…
We review the current status of knowledge concerning the early phases of star formation during cosmic dawn. This includes the first generations of stars forming in the lowest mass dark matter halos in which cooling and condensation of gas…
We simulate the formation of a metal-poor (10^-2 Zsun) stellar cluster in one of the first galaxies to form in the early Universe, specifically a high-redshift atomic cooling halo (z~14). This is the first calculation that resolves the…
Star formation remains an unsolved problem in astrophysics. Numerical studies of large-scale structure simulations cannot resolve the whole process and their approach usually assumes that only gas denser than a typical threshold can host…
The first stars, galaxies, star clusters, and direct-collapse black holes are expected to have formed in low-mass ($\sim$$10^{5}-10^{9} ~ M_{\odot}$) haloes at Cosmic Dawn ($z \sim 10 - 30$) under conditions of efficient gas cooling,…
We present a model for the star formation process during the initial collapse of dark matter haloes at redshifts z=0-30. We derive a simple expression for the characteristic stellar mass scale during this initial burst of star formation. In…
Recently the initial supersonic relative velocity between the dark matter and baryons was shown to have an important effect on galaxy formation at high redshift. We study the impact of this relative motion on the distribution of the…
The formation of the first galaxies at redshifts z~10-15 signaled the transition from the simple initial state of the universe to one of ever increasing complexity. We here review recent progress in understanding their assembly process with…