13 papers · 1 filter
Metal Abundances and Kinematics of the Ly-alpha absorbers
Sergei A. Levshakov
Both high resolution spectra of QSOs observed at the 8-10m telescopes and advanced methods of data analysis are crucial for accurate measurements of the chemical composition and ph…
On metal abundances in QSO absorbers
S. A. Levshakov
I review our recent results concerning the metal abundances in quasar absorption-line spectra obtained with the UVES/VLT, HIRES/ KECK, and STIS/HST spectrographs. The analysis is b…
Monte Carlo inversion of hydrogen and metal lines from QSO absorption spectra
Sergei A. Levshakov, Irina I. Agafonova, Wilhelm H. Kegel
A new method, based on the simulated annealing algorithm and aimed at the inverse problem in the analysis of intergalactic (interstellar) complex spectra of hydrogen and metal line…
The deuterium abundance in QSO absorption systems: a mesoturbulent approach
Sergei A. Levshakov
A new method, based on simulated annealing technique and aimed at the inverse problem in the analysis of intergalactic or interstellar complex spectra of hydrogen and metal lines,…
On the deuterium abundance at z_a = 3.514 towards APM 08279+5255
S. A. Levshakov, I. I. Agafonova, W. H. Kegel
A very low primordial deuterium abundance of D/H = 1.5 10^{-5} has recently been proposed by Molaro et al. in the Lyman limit system with log(N_HI) = 18.1 cm^{-2} at z_a = 3.514 to…
On the measurement of kinetic temperature in high redshift galactic halos
Sergei A. Levshakov, Wilhelm W. Kegel
We consider the deconvolution of the thermal and the turbulent profiles for a pair of ions with different atomic weights under the condition that the lines are formed in an absorbi…