Multiwavelength investigation of a near-solar metallicity sub-DLA at z =1.3647 towards PKS 0237-233

Abstract

We searched for 21-cm absorption associated with the z_abs = 1.3647 absorption system toward PKS 0237-233 using the GMRT. A high quality UVES spectrum shows that C I and C I* are detected at this redshift together with C II*, Mg I, Mg II, Si II, Al II, Fe II and Mn II. The complex profiles, spread over ~300 km/s, are fitted with 21 Voigt profile components. None of these components are detected in 21-cm absorption down to a detection limit of τ(3σ)\le 3x10^{-3} (or N(HI)/T_S <10^{17} cm ^-2 K^-1). We derive log N(HI)<19.30$\pm$0.30 using the Lyman alpha absorption line detected in the IUE spectrum of the quasar. Mg II, Si II and Al II column densities are consistent with near solar metallicity and we measure [O/H]>-0.33. Using photoionization models constrained by the fine-structure excitations of C I and C II, and the 21-cm optical depth, we show that the C I absorption arises predominantly either in WIM or WNM in ionization and thermal equilibrium with the meta-galactic UV background dominated by QSOs and star forming galaxies. The estimated thermal pressure of the gas is of the same order of magnitude over different velocity ranges through the absorption profile (2.6\le log [P/k cm^{-3} K]\le 4.0). The gas-phase metallicity corrected for ionization is Z>0.5 Z_\odot with a signature of Fe co-production elements being under abundant compared to α-process elements by ~0.5 dex. At z>1.9, C I absorption is usually associated with H_2 absorption arising from cold gas in DLAs. This system and the z=2.139 toward Tol 1037-270 are the only two systems known which show that C I absorption can also be detected in warm gas provided the metallicity is high enough. Interestingly, both the systems are part of unusual concentrations of absorption lines.

arXiv comment12 pages, 9 figures, accepted for publication in MNRAS

References in corpus (21)

• Structure of Stationary Photodissociation Fronts
• The VLT-UVES survey for molecular hydrogen in high-redshift damped Lyman-alpha systems
• Discovery of Damped Lyman-Alpha Systems at Redshifts Less Than 1.65 and Results on their Incidence and Cosmological Mass Density
• Probing the cosmological variation of the fine-structure constant: Results based on VLT-UVES sample
• The Distribution of Thermal Pressures in the Interstellar Medium from a Survey of C I Fine-Structure Excitation
• The VLT-UVES survey for molecular hydrogen in high-redshift damped Lyman-alpha systems: Physical conditions in the neutral gas
• The microwave background temperature at the redshift of 2.33771
• CII* Absorption in Damped Lyman Alpha Systems: (I) Star Formation Rates in a Two-Phase Medium
• A deep search for 21cm absorption in high redshift damped Lyman-$\alpha$ systems
• CII* Absorption in Damped Lyman Alpha Systems: (II) A New Window on the Star Formation History of the Universe
• Metals in the Intergalactic Medium
• The Sizes and Kinematic Structure of Absorption Systems Towards the Lensed Quasar APM08279+5255
• Molecular hydrogen at z=1.973 toward Q0013-004: Dust depletion pattern in damped Lyman-alpha systems
• Physical conditions in QSO absorbers from fine-structure absorption lines
• A New Measurements of the Cosmic Microwave Background Radiation Temperature at z = 1.97
• Spin temperatures and covering factors for HI 21-cm absorption in damped Lyman-alpha systems
• A near-solar metallicity damped Lyman-alpha system toward the BAL quasar Tol 1037-2703
• On the Nature of the Heat Source for Damped Lya Systems
• Physical conditions in the ISM towards HD185418
• The z=1.6748 C I Absorber Toward PKS 1756+237
• Kinematics and star formation activity in the z=2.03954 damped Lyman-alpha system towards PKS 0458-020

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• The ESO UVES Advanced Data Products Quasar Sample - II. Cosmological Evolution of the Neutral Gas Mass Density
• The ESO UVES Advanced Data Products Quasar Sample - VI. Sub-Damped Lyman-$\alpha$ Metallicity Measurements and the Circum-Galactic Medium
• A search for HI 21cm absorption in strong MgII absorbers in the redshift desert
• A complete sample of 21-cm absorbers at z~1.3: Giant Metrewave Radio Telescope Survey Using MgII Systems
• Thermal Pressures in the Interstellar Medium of the Magellanic Clouds
• Relationships between the HI 21-cm line strength, MgII equivalent width and metallicity in damped Lyman-alpha absorption systems
• Extent and structure of intervening absorbers from absorption lines redshifted on quasar emission lines
• An investigation of the line of sight towards QSO PKS 0237-233