Narrow Results

In this paper, the photon escape probability of Na 330.3 nm resonance line is calculated, both for slab and cylindrical geometries. The dependence of the photon escape probability on the optical depth in the line center is considered. The oscillator strength, the number density of the absorbing atoms in the ground state, and the optical depth in the line center are discussed in this calculation. The changes of the photon escape probabilities with different concentrations are calculated. This calculation will provide a method to calculate the photon escape probability for different lines.

A general method for quick and accurate evaluation of escape factor is presented, for any optical depths and any line profiles, using least square procedure. The principle of the least square procedure is discussed. As an example, the parameters are fitted when the optical depth is in the region of 0–1000, and the escape factors we obtained are in accordance with the theoretical formula.

The Bremsstrahlung radiation power is one of the important loss processes in the inertial confinement fusion. The motion of ions is usually neglected when calculating the Bremsstrahlung radiation of the plasma. We calculate the Bremsstrahlung radiation power by taking into account the motion of ions in degenerate plasma. We found a two-temperature function for Bremsstrahlung radiation of the plasma. Finally, the Bremsstrahlung optical depth is obtained for plasma.

In this work, we have assumed the non-flat FRW model of the universe. We probed the optical depth behavior of a few cosmological models, including the deceleration parameter’s parametrized form. We have considered ten such models and carried out a qualitative analysis graphically. We found that these particular lensing phenomena depend greatly on the various parametrization forms of deceleration parameter in the cosmological models. Then we compared these models to each other as well as with $\mathrm{\Lambda }$CDM model.

We study the high energy photon interaction with cosmic microwave background (CMB) and calculate the optical depth due to Euler-Heisenberg photon-photon scattering at cosmological redshift. According to our results the photon-photon scattering is predominant with respect to the Breit-Wheeler pair production at energies below 1 GeV. However, it is relevant for sources of high energy photons at high redshift z > 100. We also discuss implications of our results for two astrophysical observations of gamma-ray bursts and blazars.