We report the near-IR detection of a prominent CIV absorption in the rest-frame UV spectrum of the most distant known QSO, SDSS J104433.04−012502.2, at z = 5.80. This QSO was recently observed with XMM-Newton and it was found to be notably X-ray weak. The equivalent width of the CIV absorption feature (∼10Å) strongly supports the idea that the X-ray faintness of this QSO is due to heavy absorpt...

The present generation of radio telescopes, combined with powerful new spectrometers, is opening a new age of redshifted radio absorption-line studies. Outfitting of arrays of antennas, such as the European VLBI Network and the upgraded VLA, with flexibly tuned receivers, will measure sizes and kinematics of intervening galaxies as a function of cosmic time. Shortly after the discovery that qua...

We have searched for evidence of soft X-ray absorption by hot metals in the vicinity of the Galaxy in the spectra of a small sample of fifteen type I AGN observed with the high resolution X-ray gratings on board Chandra. This is an extension of our previous survey of hot O vii and O viii absorbing gas in the vicinity of the Galaxy. The strongest absorption signatures within a few hundred km s o...

We develop a method to calculate the column density distribution of the Lyα forest for column densities in the range 10 − 10 cm. The Zel’dovich approximation, with appropriate smoothing, is used to compute the density and peculiar velocity fields. The effect of the later on absorption profiles is discussed and it is shown to have little effect on the column density distribution. We introduce an...

We present the modeling of the absorption column performance using feed-forward and radial basis function type neural networks. The input and output data for training of the neural networks are obtained from a rigorous model of the absorption column. The results obtained form the neural network models are compared with the results obtained mainly from the simulation calculations. The results sh...

Lam Hui, Nickolay Y. Gnedin and Yu Zhang Absorption lines in the Lyα forest can be thought of as peaks in neutral hydrogen density along lines of sight. The column density distribution (the number density of absorption lines as a function of column density) is then a statistic of density peaks, which contains information about the underlying power spectrum. In particular, we show that the slope...

CO2 emissions from combustion flue gases have turned into a major factor in global warming. Post-combustion carbon capture (PCC) from industrial utility flue gases by reactive absorption can substantially reduce the emissions of the greenhouse gas CO2. To test a new solvent (AIT600) for this purpose, a small pilot plant was used. This paper presents the results of studies ...

In order to better understand the budget of carbon dioxide in the Earth's atmosphere it is necessary to develop a global high precision understanding of the carbon dioxide column. In order to uncover the 'missing s ink that is responsible for the large discrepancies in the budget as we presently understand it calculation has indicated that measurement accuracy on the order of 1 ppm is necessary...

In this paper we present computations of the integrated metal-ion column densities produced in the post-shock cooling layers behind fast, radiative shock-waves. For this purpose, we have constructed a new shock code that calculates the non-equilibrium ionization and cooling; follows the radiative transfer of the shock self-radiation through the post-shock cooling layers; takes into account the ...