Hadi Rahmani

The ESO UVES advanced data products quasar sample - VI. Sub-damped Lyman α metallicity measurements and the circumgalactic medium

The circumgalactic medium (CGM) can be probed through the analysis of absorbing systems in the line of sight to bright background quasars. We present measurements of the metallicity of a new sample of 15 sub-damped Lyman alpha absorbers (sub-DLAs, defined as absorbers with 19.0 \textless logN(HI) \textless 20.3) with redshift 0.584 \textless= z(abs) \textless= 3.104 from the ESO Ultra-Violet Echelle Spectrograph (UVES) Advanced Data Products Quasar Sample (EUADP). We combine these results with other measurements from the literature to produce a compilation of metallicity measurements for 92 sub-DLAs as well as a sample of 362 DLAs. We apply a multi-element analysis to quantify the amount of dust in these two classes of systems. We find that either the element depletion patterns in these systems differ from the Galactic depletion patterns or they have a different nucleosynthetic history than our own Galaxy. We propose a new method to derive the velocity width of absorption profiles, using the modelled Voigt profile features. The correlation between the velocity width Delta V-90 of the absorption profile and themetallicity is found to be tighter for DLAs than for sub-DLAs. We report hints of a bimodal distribution in the [Fe/H] metallicity of low redshift (z \textless 1.25) sub-DLAs, which is unseen at higher redshifts. This feature can be interpreted as a signature from the metal-poor, accreting gas and the metal-rich, outflowing gas, both being traced by sub-DLAs at low redshifts.

Cold gas and a Milky Way-type 2175-Å bump in a metal-rich and highly depleted absorption system

We report the detection of a strong Milky Way-type 2175 \AA

Nature of the absorbing gas associated with a galaxy group at z∼0.4

extinction bump at

Discovery of a Perseus-like cloud in the early Universe - H I-to-H2 transition, carbon monoxide and small dust grains at zabs≈ 2.53 towards the quasar J0000+0048

z

A study of the circumgalactic medium at z ∼ 0.6 using damped Lyman α galaxies

= 2.1166 in the quasar spectrum towards SDSS J121143.42+083349.7 from the Sloan Digital Sky Survey (SDSS) Data Release 10. We conduct follow up observations with the Echelle Spectrograph and Imager (ESI) onboard the Keck-II telescope and the Ultraviolet and Visual Echelle Spectrograph (UVES) on the VLT. This 2175 \AA

THE DUST, NEBULAR EMISSION, AND DEPENDENCE ON QSO RADIO PROPERTIES OF THE ASSOCIATED Mg II ABSORPTION LINE SYSTEMS

absorber is remarkable in that we simultaneously detect neutral carbon (C I), neutral chlorine (Cl I), and carbon monoxide (CO). It also qualifies as a damped Lyman alpha system. The J1211+0833 absorber is found to be metal-rich and has a dust depletion pattern resembling that of the Milky Way disk clouds. We use the column densities of the C I fine structure states and the C II/C I ratio (under the assumption of ionization equilibrium) to derive the temperature and volume density in the absorbing gas. A Cloudy photoionization model is constructed, which utilizes additional atoms/ions to constrain the physical conditions. The inferred physical conditions are consistent with a canonical cold (T

Observational signatures of a warped disk associated with cold-flow accretion

\sim

CO-dark molecular gas at high redshift: very large H2 content and high pressure in a low-metallicity damped Lyman alpha system

100 K) neutral medium with a high density (