Related papers: Hydrogen Recombination with Multilevel atoms
The light curves of type-II supernovae (SNe) are believed to be highly affected by recombination of hydrogen that takes place in their envelopes. In this work, we analytically investigate the transition from a fully ionized envelope to a…
We investigate the ionization of hydrogen in a dynamic Solar atmosphere. We show that the time scale for ionization/recombination can be estimated from the eigenvalues of a modified rate matrix where the optically thick Lyman transitions…
More than half of the atoms in the Universe recombined via forbidden transitions, so that accurate treatment of the forbidden channels is important in order to follow the cosmological recombination process with the level of precision…
We study the reionization of Helium II by quasars using a numerical approach that combines 3D radiative transfer calculations with cosmological hydrodynamical simulations. Sources producing the ionizing radiation are selected according to…
Accurate rates for energy-degenerate l-changing collisions are needed to determine cosmological abundances and recombination. There are now several competing theories for the treatment of this process, and it is not possible to test these…
Cosmological hydrogen recombination has recently been the subject of renewed attention because of its importance for predicting the power spectrum of cosmic microwave background anisotropies. It has become clear that it is necessary to…
Many large scale numerical simulations of astrophysical plasmas must also reproduce the hydrogen ionization and the resulting emission spectrum, in some cases quite accurately. We describe a compact model hydrogen atom that can be readily…
The reionization of cosmic hydrogen marks a critical juncture in the history of structure formation in the universe. Here we present a new formulation of the standard reionization equation for the evolution of the volume-averaged HII…
In this paper, the influence of chemi-ionization processes in $H^*(n \ge 2) + H(1s)$ collisions, as well as the influence of inverse chemi-recombination processes on hydrogen atom excited-state populations in solar photosphere, are compared…
We show that the process of photoionizing a gas of atomic hydrogen and helium by line radiation whose energy is slightly above the helium single-ionization threshold is unstable if the helium fraction by number is less than approximately…
Reionization is a process whereby hydrogen (and helium) in the Universe is ionized by the radiation from first luminous sources. Theoretically, the importance of the reionization lies in its close coupling with the formation of first cosmic…
Context. Radical chemical reactions on cosmic dust grains play a crucial role in forming various chemical species. Among different radicals, the hydroxyl (OH) is one of the most important ones, with a rather specific chemistry. Aims. The…
We calculate the recombination spectra of the He-like ions He~I, C~V, N~VI, O~VII, Ne~IX, Mg~XI, Si~XIII, S~XV, Ar~XVII, Ca~XIX, and Fe~XXV. We include the following physical processes: radiative recombination, dielectronic recombination,…
Hydrogen recombination in the early Universe in the presence of a magnetic field is studied. An equation for the temperature of recombination in the presence of a magnetic field is derived. Limiting cases of weak and strong fields are…
We survey the results of a long-term study of the process of radiative recombination. A rigorous theory of nonrelativistic electron radiative recombination with a hydrogen-like ion is used to calculate the total cross section of the…
The reionization of the second electron of helium shapes the physical state of intergalactic gas at redshifts between 2 < z < 5. Because performing full in situ radiative transfer in hydrodynamic simulations is computationally expensive for…
The recombination of an electron with an (initially) hydrogen-like ion is investigated. The effect of the electron-electron interaction is treated rigorously to the first order in the parameter 1/Z and within the screening-potential…
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…
We present first results on the quantitative spectroscopic analysis of the photospheric-phase of Type II supernovae (SN). The analyses are based on the non-LTE model atmosphere code, CMFGEN, of Hillier & Miller (1998). A key asset of CMFGEN…
We present spectral fits to five epochs of the typical Type Ib supernova 1999dn using the generalized, non-LTE, stellar atmospheres code PHOENIX. Our goal is threefold: to determine basic physical properties of the supernova ejecta, such as…