Investigating the Metal Line Systems at Z=1.9 toward J2233-606 in the HDF-S

Abstract

The combination of STIS and optical spectroscopy with STIS imaging of the field surrounding J2233-606 afford a unique opportunity to study the physical nature of the Quasar Absorption Line systems. We present an analysis of the ionization state, chemical abundances, and kinematic characteristics of two metal-line systems at z=1.92 and z=1.94 toward J2233-606. We focus on these two systems because (i) the observations provide full coverage of the Lyman series, hence an accurate determination of their HI column densities and (ii) the metal-line transitions allow a measurement of their ionization state. Line-profile fits of the Lyman series for the two systems indicate log N(HI) = 17.15 \pm 0.02 cm^-2 evenly distributed between two components for the z=1.92 system and log N(HI) = 16.33 \pm 0.04 cm^-2 for the z=1.94 system. By comparing observed ionic ratios of C and Si against calculations performed with the CLOUDY software package, we find the ionization state is high and well constrained in both systems. Applying ionization corrections to the measured ionic column densities, we determine that the systems exhibit significantly different metallicities: ~ 1/50 solar and < 1/200 solar for the two components of z=1.92 and ~40% solar at z=1.94. The properties of the z=1.92 system are consistent with a low metallicity galaxy (e.g. a dwarf galaxy) as well as absorption by large scale structure of the IGM. On the other hand, the high metallicity of the z=1.94 system suggests significant star formation and is therefore most likely associated with a galactic system. Furthermore, we predict it is the most likely to be observed with the STIS imaging and follow-up observations. If a galaxy is identified, our results provide direct measurements on the properties of the ISM for a z~2 galaxy.

9 pages, 6 encapsulated figures, LaTeX2e, uses emulateapj.sty and onecolfloat.sty (included). Submitted to the Astronomical Journal

References in corpus (5)

• Chemical Abundances of the Damped Lya Systems at z>1.5
• Protogalactic Disk Models of Damped Lya Kinematics
• The Physical Nature of the Lyman Limit Systems
• The Multiple Phases of Interstellar and Halo Gas in a Possible Group of Galaxies at z~1
• The metal absorption systems of the Hubble Deep Field South QSO

Cited by in corpus (22)

• The SDSS Damped Lya Survey: Data Release 3
• Detection of Pristine Gas Two Billion Years after the Big Bang
• The Hubble Deep Fields
• Dissecting the properties of optically-thick hydrogen at the peak of cosmic star formation history
• The physical properties of z>2 Lyman limit systems: new constraints for feedback and accretion models
• A Hubble Space Telescope Study of Lyman Limit Systems: Census and Evolution
• High-Redshift Metals. II. Probing Reionization Galaxies with Low-Ionization Absorption Lines at Redshift Six
• The AGN Outflow in the HDFS Target QSO J2233-606 from a High-Resolution VLT/UVES Spectrum
• Super-Solar Super Lyman Limit Systems
• Chemical abundances in quasar host galaxies and environments from narrow absorption line systems
• The Origin of a Chemically Enriched lya Absorption System at z=0.167
• Probing the metallicity and ionization state of the circumgalactic medium at z~6 and beyond with OI absorption
• An X-ray Mini-survey of Nearby Edge-on Starburst Galaxies II. The Question of Metal Abundance
• The Keck+Magellan Survey for Lyman Limit Absorption II: A Case Study on Metallicity Variations
• Rapid-response mode VLT/UVES spectroscopy of super iron-rich gas exposed to GRB 080310. Evidence of ionization in action and episodic star formation in the host
• Spectral energy distribution of the metagalactic ionizing radiation field from QSO absorption spectra
• Possible Population III Remnants at Redshift 3.5
• Baryons: What, When and Where?
• Inhomogeneous metal enrichment at z \sim 1.9: the Lyman limit systems in the spectrum of the HDF-S quasar
• High-Resolution Spectroscopy from 3050 to 10000 A of the HDF-S QSO J2233-606 with UVES at the ESO VLT
• Super-Solar Metallicity in Weak Mg II Absorption Systems at z ~ 1.7
• Metal abundances and kinematics of quasar absorbers.- I. Absorption systems toward J2233-606