相关论文: Two-Photon 2s<->1s Transitions during Recombinatio…
The subject of cosmological hydrogen recombination has received much attention recently because of its importance to predictions for and cosmological constraints from CMB observations. While the central role of the two-photon decay 2s->1s…
A rigorous QED theory of the multiphoton decay of excited states in hydrogen atom is presented. The "two-photon" approximation is formulated which is limited by the one-photon and two-photon transitions including cascades transitions with…
We study the two-photon process for the transitions ns --> 1s and nd --> 1s in hydrogen up to large n. For n<=20 we provide simple analytic fitting formulae to describe the non-resonant part of the two-photon emission profiles. Combining…
A new approach to the cosmological recombination problem is presented, which completes our previous analysis on the effects of two-photon processes during the epoch of cosmological hydrogen recombination, accounting for ns-1s and nd-1s…
The dependences on z of fractional number densities of H+ and He+ ions are calculated with a proper allowance for two-photon decays of upper levels of hydrogen and parahelium and radiative transfer in intercombination line 2 3P_1 --> 1 1S_0…
Hydrogen recombination is one of the most important atomic processes in many astrophysical objects such as Type II supernova (SN~II) atmospheres, the high redshift universe during the cosmological recombination era, and H II regions in the…
Induced emission due to the presence of soft CMB photons slightly increases the two-photon decay rate of the 2s level of hydrogen defining the rate of cosmological recombination. This correspondingly changes the degree of ionization, the…
We give a formulation of the radiative transfer equation for Lyman alpha photons which allows us to include the two-photon corrections for the 3s-1s and 3d-1s decay channels during cosmological hydrogen recombination. We use this equation…
We discuss the evolution of the ratio in number of recombinations due to 2s two photon escape and due to the escape of Lyman-$\alpha$ photons from the resonance during the epoch of cosmological recombination, within the width of the last…
The advent of precise measurements of the cosmic microwave background (CMB) anisotropies has motivated correspondingly precise calculations of the cosmic recombination history. Cosmic recombination proceeds far out of equilibrium because of…
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…
In this paper we consider the effects of resonance and electron scattering on the escape of Lyman alpha photons during cosmological hydrogen recombination. We pay particular attention to the influence of atomic recoil, Doppler boosting and…
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…
In this paper we compute the emission coming from the direct recombination of free electrons to a given shell (n>=2) during the epoch of cosmological hydrogen recombination. This contribution leads to a total of one photon per recombined…
In our recent papers (Kereslidze et all 2019a, 2021) a non-standard quasi-molecular mechanism was suggested and applied to treat the cosmological recombination. It was assumed that in the pre-recombination stage of evolution of the Universe…
The process of recombination for the hydrogen atom in the heat bath creating the blackbody radiation is descibed within the frameworks of quantum electrodynamics. For this purpose the self-energy for unbound electron in the field of the…
Energy-changing electron-hydrogen atom collisions are crucial to regulating the energy balance in astrophysical and laboratory plasmas and relevant to the formation of stellar atmospheres, recombination in H-II clouds, primordial…
The resonant spectra of hydrogen and anti-hydrogen atoms in the presence of an external electric field are compared theoretically. It is shown that nonresonant corrections to the transition frequency contain terms linear in the electric…
A new approach is laid out to investigate the two photon atomic transitions. It is based on application of the finite basis solutions constructed from the Bernstein Polynomial (B-Polynomial) sets. We show that such an approach provides a…
Radiative corrections to the decay rate of n=2 states of hydrogenic ions are calculated. The transitions considered are the M1 decay of the 2s state to the ground state and the E1(M2) decays of the $2p_{1/2}$ and $2p_{3/2}$ states to the…