相关论文: Resolving the Formation of Protogalaxies. I. Viria…
The formation and evolution of galaxies is one of the great outstanding problems of astrophysics. Within the broad context of hierachical structure formation, we have only a crude picture of how galaxies like our own came into existence. A…
The density irregularities and holes visible in many Chandra X-ray images of cluster and galactic cooling flows can be produced by symmetrically heated gas near the central galactic black hole. As the heated gas rises away from the galactic…
We present a theoretical model for primordial star formation. First we describe the structure of the initial gas cores as virialized, quasi-hydrostatic objects in accord with recent high resolution numerical studies. The accretion rate can…
Massive primordial halos exposed to moderate UV backgrounds are the potential birthplaces of supermassive black holes. In such a halo, an initially isothermal collapse will occur, leading to high accretion rates of…
In our modern understanding of galaxy formation, every galaxy forms within a dark matter halo. The formation and growth of galaxies over time is connected to the growth of the halos in which they form. The advent of large galaxy surveys as…
Cosmological simulations of galaxy formation appear to show a two-phase character with a rapid early phase at z>2 during which in-situ stars are formed within the galaxy from infalling cold gas followed by an extended phase since z<3 during…
In this paper we examine aspects of primordial star formation in a gravitino warm dark matter universe with a cosmological constant. We compare a set of simulations using a single cosmological realization but with a wide range of warm dark…
Major progress has been made over the last few years in understanding hydrodynamical processes on cosmological scales, in particular how galaxies get their baryons. There is increasing recognition that a large part of the baryons accrete…
We discuss a possible delay experienced by protogalaxies with low column density of gas in forming stars over large scales. After the hydrogen has recombined, as the external ionizing UV flux decreases and the metal abundance $Z$ increases,…
Winds from pregalactic starbursts and 'miniquasars' may pollute the IGM with metals and raise its temperature to a high adiabat, and so inhibit the formation of early galaxies. We compute the thermal history of the IGM when it experiences a…
The first stars are known to form in primordial gas, either in minihalos with about $10^6$~M$_\odot$ or so-called atomic cooling halos of about $10^8$~M$_\odot$. Simulations have shown that gravitational collapse and disk formation in…
The formation of disk galaxies is one of the most outstanding problems in modern astrophysics and cosmology. We review the progress made by numerical simulations carried out on large parallel supercomputers. Recent progress stems from a…
Stars are often observed to form in clusters. It is therefore important to understand how such a region of concentrated mass is assembled out of the diffuse medium and its properties eventually prescribe the important physical mechanisms…
We calculate the evolution of linear density and temperature perturbations in a universe with dark matter, baryons, and radiation, from cosmic recombination until the epoch of the first galaxies. In addition to gravity, the perturbations…
Population III stars forming in the infant universe at z=30 heralded the end of the cosmic dark ages. They are presumed to be assembled in so-called minihaloes with virial temperatures of a few thousand K where collapse is triggered by…
Cosmological simulations of galaxy formation predict a universal form for the mass profile of dark matter (DM) halos from cluster to galaxy scales. Remarkably few interesting constraints exist, however, on DM halos in early-type galaxies.…
The standard model for gravitational structure formation in astrophysics, astronomy, and cosmology is questioned. Cold dark matter (CDM) hierarchical clustering cosmology neglects particle collisions, viscosity, turbulence and diffusion and…
We use recent observations of the HI-mass function to constrain galaxy formation. The data conflicts with the standard model where most of the gas in a low-mass dark matter halo is assumed to settle into a disk of cold gas that is depleted…
Clusters of galaxies are studied from a theoretical point of view, comparing with observational results whenever possible. The problem is approached both analytically as well as by means of high-resoultion numerical simulations. The dark…
We perform a suite of cosmological simulations in the LCDM paradigm of the formation of the first structures in the Universe prior to astrophysical reheating and reionization (15<~z<200). These are the first simulations initialized in a…