Fine-structure diagnostics of neutral carbon toward HE 0515-4414

Abstract

New high-resolution high signal-to-noise spectra of the $z=1.15$ damped Lyman $\alpha$ (DLA) system toward the quasi-stellar object HE 0515-4414 reveal absorption lines of the multiplets 2 and 3 in \ion{C}{i}. The resonance lines are seen in two components with total column densities of $\log N=13.79\pm 0.01$ and $\log N=13.36\pm 0.01$, respectively. The comparision of theoretical calculations of the relative fine-structure population with the ratios of the observed column densities suggests that the \ion{C}{i} absorbing medium is either very dense or exposed to very intense UV radiation. The upper limit on the local UV energy density is 100 times the galactic UV energy density, while the upper limit on the \ion{H}{i} number density is 110 cm${}^{-3}$. The excitation temperatures of the ground state fine-structure levels of $T=15.7$ and $T=11.1$ K, respectively, are consistent with the temperature-redshift relation predicted by the standard Friedmann cosmology. The cosmic microwave background radiation (CMBR) is only a minor source of the observed fine-structure excitation.

5 pages, 5 figures, uses A&A macro package, gzipped tar archive, accepted by A&A

References in corpus (4)

• The Distribution of Thermal Pressures in the Interstellar Medium from a Survey of C I Fine-Structure Excitation
• The microwave background temperature at the redshift of 2.33771
• Physical conditions in QSO absorbers from fine-structure absorption lines
• The cosmic microwave background radiation temperature at z = 3.025 toward QSO 0347--3819

Cited by in corpus (18)

• The VLT-UVES survey for molecular hydrogen in high-redshift damped Lyman-alpha systems: Physical conditions in the neutral gas
• Probing the variability of the fine-structure constant with the VLT/UVES
• First detection of CO in a high-redshift DLA
• Most precise single redshift bound to Delta alpha/alpha
• Understanding Physical Conditions in High Redshift Galaxies through C I Fine Structure Lines: Data and Methodology
• The Evolution of Lyman alpha Absorbers in the Redshift Range 0.5<z<1.9
• Fundamental physics with ESPRESSO: Precise limit on variations in the fine-structure constant towards the bright quasar HE 0515$-$4414
• Detection of molecular hydrogen at z=1.15 toward HE 0515-4414
• Molecular hydrogen in damped Ly-alpha systems: clues to interstellar physics at high-redshift
• The Local Effects of Cosmological Variations in Physical 'Constants' and Scalar Fields I. Spherically Symmetric Spacetimes
• Thermal Pressures in the Interstellar Medium of the Magellanic Clouds
• HE 0515-4414 - an unusual sub-damped Ly alpha system revisited
• The Local Effects of Cosmological Variations in Physical 'Constants' and Scalar Fields II. Quasi-Spherical Spacetimes
• VLT/UVES constraints on the carbon isotope ratio 12C/13C at z=1.15 toward the quasar HE 0515-4414
• Evolution strategies applied to the problem of line profile decomposition in QSO spectra
• Thermal Pressures in the Interstellar Medium away from Stellar Environments
• The Mystery of Alpha and the Isotopes
• Signals of the cosmological reionization in the radio sky through C and O fine structure lines