منابع مشابه
Numerical simulations of quasar absorbers
The physical state of the intergalactic medium can be probed in great detail with the intervening absorption systems seen in quasar spectra. The properties of the Hydrogen absorbers depend on many cosmological parameters, such as the matter-power spectrum, reionisation history, ionising background and the nature of the dark matter. The spectra also contain metal lines, which can be used to cons...
متن کاملDusty MgII Absorbers: Implications for the GRB/Quasar Incidence Discrepancy
There is nearly a factor of four difference in the number density of intervening MgII absorbers as determined from gamma-ray burst (GRB) and quasar lines of sight. We use a Monte-Carlo simulation to test if a dust extinction bias can account for this discrepancy. We apply an empirically determined relationship between dust column density and MgII rest equivalent width to simulated quasar sight-...
متن کاملInvestigating lensing by absorbers in the 2dF-Quasar survey
We use the first data release of the 2-degree Field Quasar survey to investigate the effect of gravitational magnification by foreground absorbing systems on background quasars. We select two populations of quasars from this sample: one with strong Mg II/Fe II absorbers and one without. The selection is done in such a way that the two populations have the same redshift distribution and the abso...
متن کاملMetal Abundances and Ionization in Quasar Intrinsic Absorbers
This paper provides a general reference for deriving the ionizations and metal abundances for absorption-line clouds in photoionization equilibrium with a QSO spectrum. The results include a quantitative assessment of the theoretical uncertainties and Ðrm lower limits on the metallicities when no ionization constraints are available. The calculations applied to the best available column densiti...
متن کاملNUMERICAL SIMULATIONS OF THE PHASE TRANSITIONS IN CLUSTERS
We have studied the phase transitions in atomic clusters by molecular dynamics simulation, assuming Lennard-Jones interatomic pair potential. Calculations are performed by DAP parallel computer. The results are analyzed by simulating their orientational distribution plots (dot-plot), and neutron diffraction patterns. It is shown that all the main features of the bulk phase transitions are e...
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ژورنال
عنوان ژورنال: Proceedings of the International Astronomical Union
سال: 2005
ISSN: 1743-9213,1743-9221
DOI: 10.1017/s1743921305002590