相关论文: Cosmic rays and the primordial gas
Within the precise cosmological framework provided by the Lambda-Cold Dark Matter model and standard Big Bang nucleosynthesis, the chemical evolution of the pregalactic gas can now be followed with accuracy limited only by the uncertainties…
We use hydrodynamical simulations of two Milky Way-mass galaxies to demonstrate the impact of cosmic-ray pressure on the kinematics of cool and warm circumgalactic gas. Consistent with previous studies, we find that cosmic-ray pressure can…
The first stars are expected to form through molecular-hydrogen (H$_2$) cooling, a channel that is especially sensitive to the thermal and ionization state of gas, and can thus act as a probe of exotic energy injection from decaying or…
Cosmic rays produce molecular cluster ions as they pass through the lower atmosphere. Neutral molecular clusters such as dimers and complexes are expected to make a small contribution to the radiative balance, but atmospheric absorption by…
Among many physical processes involved in star formation, radiation transfer is one of the key processes since it dominantly controls the thermodynamics. Because metallicities control opacities, they are one of the important environmental…
Dissociation of molecular hydrogen by secondary electrons produced by cosmic ray or X-ray ionization plays a crucial role in the chemistry of the densest part of molecular clouds. Here we study the effect of the mean kinetic energy of…
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…
In the context of the solar atmosphere, we re-examine the role of of neutral and ionized species in dissipating the ordered energy of intermediate-mode MHD waves into heat. We solve conservation equations for the hydrodynamics and for…
We study the formation of first molecules, negative Hydrogen ions and molecular ions in model of the Universe with cosmological constant and cold dark matter. The cosmological recombination is described in the framework of modified model of…
The evolution of nonlinear density fluctuations around the Jeans mass shortly after cosmological recombination is analyzed using a 3D hydrodynamics/dark--matter code. The Cosmic Background Radiation (CBR) exerts Compton friction on free…
The addition of metals to any gas can significantly alter its evolution by increasing the rate of radiative cooling. In star-forming environments, enhanced cooling can potentially lead to fragmentation and the formation of low-mass stars,…
It has been proposed that primordial gas in early dark matter halos, with virial temperatures above 10^4 K, can avoid fragmentation and undergo rapid collapse, possibly resulting in a supermassive black hole (SMBH). This requires the gas to…
The growth of structure from scale-free initial conditions is one of the most important tests of cosmological simulation methods, providing a realistically complex problem in which numerical results can be compared to rigorous analytic…
The ionization fraction is an important factor in determining the chemical and physical evolution of star forming regions. In the dense, dark starless cores of such objects, the ionization rate is dominated by cosmic rays; it is therefore…
We present a simplified chemical and thermal model designed to allow computationally efficient study of the thermal evolution of metal-poor gas within large numerical simulations. Our main simplification is the neglect of the molecular…
The development of primordial inhomogeneities into the non-linear regime and the formation of the first bound objects mark the transition from a simple cooling universe -- described by just a few parameters -- to a very messy hot one -- the…
The early reionization of the intergalactic medium, which is favored from the WMAP temperature-polarization cross-correlations, contests the validity of the standard scenario of structure formation in the cold dark matter cosmogony. It is…
We present results from self-consistent 3D numerical simulations of cosmic structure formation with a multi-frequency radiative transfer scheme and non-equilibrium molecular chemistry of 13 primordial species (e-, H, H+, H-, He, He+, He++,…
Cosmic rays (CRs) are the primary driver of ionization in star forming molecular clouds (MCs). Despite their potential impacts on gas dynamics and chemistry, no simulations of star cluster formation following the creation of individual…
The physical origin of high velocity cool gas seen in galactic winds remains unknown. Following Wang (1995), we argue that radiative cooling in initially hot thermally-driven outflows can produce fast neutral atomic and photoionized cool…