5 papers
On the Field-Aligned Particle Acceleration in the presence of Electron-Positron Pairs
S. Shibata, J. Miyazaki, F. Takahara
We study self-consistency for the pulsar polar cap model. In general, there will remain an unscreened electric field at the pair production front (PPF). We have derived the conditi…
The D/H ratio at z=0.7 toward Q 1718+4807
Sergei A. Levshakov, Wilhelm H. Kegel, Fumio Takahara
The apparent discrepancy between low and high D abundances derived from QSO spectra may be caused by spatial correlations in the stochastic velocity field. If one accounts for such…
Primordial Deuterium Abundance Measurements
Sergei A. Levshakov, Wilhelm H. Kegel, Fumio Takahara
Deuterium abundances measured recently from QSO absorption-line systems lie in the range from 3 10^{-5} to 3 10^{-4}, which shed some questions on standard big bang theory. We show…
The primordial deuterium abundance : problems and prospects
Sergei A. Levshakov, Fumio Takahara, Wilhelm H. Kegel
The current status of extragalactic deuterium abundance is discussed using two examples of `low' and `high' D/H measurements. We show that the discordance of these two types of D a…
How accurately can the deuterium abundance be determined ?
S. A. Levshakov, W. H. Kegel, F. Takahara
By using a Reverse Monte Carlo technique aimed at the inverse problem in the analysis of the H+D Ly-a absorption from QSO spectra we have estimated the physical parameters of the g…