Molecular Hydrogen in a Damped Lyman-alpha System at z_abs=4.224

Abstract

We present the direct detection of molecular hydrogen at the highest redshift known today (z_abs=4.224) in a Damped Lyman-alpha (DLA) system toward the quasar PSS J1443+2724. This absorber is remarkable for having one of the highest metallicities amongst DLA systems at z_abs>3, with a measured iron abundance relative to Solar of -1.12+/-0.10. We provide for the first time in this system accurate measurements of NI, MgII, SII and ArI column densities. The sulfur and nitrogen abundances relative to Solar, -0.63+/-0.10 and -1.38+/-0.10 respectively, correspond exactly to the primary nitrogen production plateau. H2 absorption lines are detected in four different rotational levels (J=0, 1, 2 and 3) of the vibrational ground-state in three velocity components with total column densities of log N(H2)=17.67, 17.97, 17.48 and 17.26 respectively. The J=4 level is tentatively detected in the strongest component with log N(H2)~14. The mean molecular fraction is log f=-2.38+/-0.13, with f=2N(H2)/(2N(H2)+N(HI)). We also measure log N(HD)/N(H2)<-4.2. The excitation temperatures T_{01} for the two main components of the system are 96 and 136 K respectively. We argue that the absorbing galaxy, whose star-formation activity must have started at least 2-5x10^8 yrs before z=4.224, is in a quiescent state at the time of observation. The density of the gas is small, n_H<=50 cm^{-3}, and the temperature is of the order of T~90-180 K. The high excitation of neutral carbon in one of the components can be explained if the temperature of the Cosmic Microwave Background Radiation has the value expected at the absorber redshift, T=14.2 K.

arXiv comment13 pages, 3 figures, accepted for publication in ApJ Letters

References in corpus (20)

• Molecular Gas at High Redshift
• Structure of Stationary Photodissociation Fronts
• Heavy element abundances in blue compact galaxies
• Spectroscopy of Outlying H II Regions in Spiral Galaxies: Abundances and Radial Gradients
• On The Cosmic Origins Of Carbon And Nitrogen
• The Age-Metallicity Relation of the Universe in Neutral Gas: The First 100 Damped Lya Systems
• The VLT-UVES survey for molecular hydrogen in high-redshift damped Lyman-alpha systems
• Molecular gas and dust around a radio-quiet quasar at redshift 4.7
• The Abundances of Nitrogen and Oxygen in Damped Lyman Alpha Systems
• Molecular hydrogen, deuterium and metal abundances in the damped Ly-alpha system at z = 3.025 toward QSO 0347-3819
• The UCSD HIRES/KeckI Damped Lya Abundance Database: I. The Data
• Gamma-Ray Burst in a Molecular Cloud: Destruction of Dust and H2, and Emergent Spectrum
• Early stages of Nitrogen enrichment in galaxies: Clues from measurements in damped Lyman alpha systems
• Physical conditions in QSO absorbers from fine-structure absorption lines
• Molecular Hydrogen in the Damped Ly alpha Absorber of Q1331+170
• Molecular hydrogen in damped Ly-alpha systems: clues to interstellar physics at high-redshift
• Cold Neutral Gas in a z=4.2 Damped Lyman-alpha System: The Fuel for Star Formation
• Ar I as a tracer of ionization evolution
• Hints of star fomation at z>6: the chemical abundances of the DLA system in the QSO BRI 1202-0725 (z_abs = 4.383)
• Galaxies Associated with z~4 Damped Lya Systems: I. Imaging and Photometric Selection

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