相关论文: How small were the first cosmological objects?

We investigate the baryon fraction in dark matter haloes formed in non-radiative gas-dynamical simulations of the LambdaCDM cosmogony. By combining a realisation of the Millennium Simulation (Springel et al.) with a simulation of a smaller…

X-ray emission from hot (T = 10^7 K) interstellar gas in massive elliptical galaxies indicates that 10^{10} M_sun has cooled over a Hubble time, but optical and radio evidence for this cold gas is lacking. We provide detailed theoretical…

The halo of our Galaxy is populated with a significant number of high-velocity clouds (HVCs) moving with a speed up to $500$ km/s. It is suggested that these HVCs might contain a non-negligible fraction of the missing baryons. The main aim…

In hierarchical models of structure formation, an early cosmic UV background (UVB) is produced by the small (T_vir < 10^4 K) halos that collapse before reionization. The UVB at energies below 13.6eV suppresses the formation of stars or…

We show that a global relation between baryonic mass and virial velocity can be constructed from the scale of dwarf galaxies up to that of rich galaxy clusters. The slope of this relation is close to that expected if dark matter halos form…

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…

The density distribution of the inter-galactic medium is an uncertain but highly important issue in the study of cosmic reionization. It is expected that there are abundant gas clouds hosted by low-mass "minihalos" in the early universe,…

We study structure formation in cosmological void regions using high-resolution hydrodynamical simulations. Despite being significantly underdense, voids are populated abundantly with small dark matter halos which should appear as dwarf…

(Abridged) Our aim is to investigate whether the presence of baryons can have any significant influence on the properties of the local Hubble flow which has proved to be "cold". We use two cosmological zoom simulations in the standard LCDM…

Rotation of galactic objects has been seen in the cosmic microwave background (CMB) that could be ascribed to molecular hydrogen clouds with, or without, dust contamination and contamination from other sources. We model the clouds using the…

We have reviewed the chemistry and cooling behaviour of low-density (n<10^4 cm^-3) primordial gas and devised a cooling model wich involves 19 collisional and 9 radiative processes and is applicable for temperatures in the range (1 K < T <…

Systematic uncertainties in the mass measurement of galaxy clusters limit the cosmological constraining power of future surveys that will detect more than $10^5$ clusters. Previously, we argued that aperture masses can be inferred more…

Population III stars are the first stars in the Universe to form at z=20-30 out of a pure hydrogen and helium gas in minihalos of 10^5-10^6 M$_\odot$ . Cooling and fragmentation is thus regulated via molecular hydrogen. At densities above…

The cosmic microwave background (CMB) monopole temperature evolves with the inverse of the cosmological scale factor, independent of many cosmological assumptions. With sufficient sensitivity, real-time cosmological observations could thus…

The concentrations of the cuspy dark matter halos predicted by simulations of cold dark matter are related to the cosmology in which the halos form. Observational constraints on halo concentration therefore map into constraints on…

We simulate the evolution of the intergalactic medium (IGM) in a universe dominated by a cosmological constant. We find that within a few Hubble times from the present epoch, the baryons will have two primary phases: one phase composed of…

The post-recombination streaming of baryons through dark matter keeps baryons out of low mass (<10^6 solar masses) halos coherently on scales of a few comoving Mpc. It has been argued that this will have a large impact on the 21-cm signal…

We analyze the physical conditions of the cool, photoionized (T $\sim 10^4$ K) circumgalactic medium (CGM) using the COS-Halos suite of gas column density measurements for 44 gaseous halos within 160 kpc of $L \sim L^*$ galaxies at $z \sim…

The first stars in the Universe are predicted to have been much more massive than the Sun. Gravitational condensation accompanied by cooling of the primordial gas due to molecular hydrogen, yields a minimum fragmentation scale of a few…

The primordial gas in the earliest dark matter halos, collapsing at redshifts around z=20, with masses M_halo=10^6 M_sun, and virial temperatures T_vir<10^4K, relied on the presence of molecules for cooling. Several theoretical studies have…