Neutral carbon in diffuse interstellar medium: abundance matching with H2 for DLAs at high redshifts

Abstract

We present the study of CI/H${}_2$ relative abundance in the diffuse cold neutral medium. Using the chemical and thermal balance model we calculated the dependence of CI/H${}_2$ on the main parameters of the medium: hydrogen number density, metallicity, strength of the UV field, and cosmic ray ionization rate (CRIR). We show that observed relative CI and H${}_2$ column densities in damped Lyman alpha systems (DLAs) at high redshifts can be reproduced within our model assuming the typically expected conditions in the diffuse cold neutral medium (CNM). Using the additional observed information the on metallicity, HI column density, and excitation of CI fine-structure levels, as well as temperature we estimated for a wide range metallicities in the CNM at high redshifts that CRIRs to be in the range from $\sim 10^{-16}$ to $\mathrm{few}\times 10^{-15}{\mathrm{s}}^{-1}$, hydrogen number densities to be in range $\sim 10-10^3$cm${}^{-3}$, and UV field in range from $10^{-2}$ to $\mathrm{few}\times 10^2$ of Mathis field. We argue, that since the observed quantities used in this work are quite homogeneous and much less affected by the radiative transfer effects (in comparison with e.g. dissociation of HD and UV pumping of H${}_2$ rotational levels) our estimates are quite robust against the assumption of the exact geometrical model of the cloud and local sources of the UV field.

arXiv comment11 pages, 6 figures

References in corpus (46)

• The chemical composition of the Sun
• The Neutral Atomic Phases of the ISM in the Galaxy
• The UMIST database for astrochemistry 2012
• An Analysis of the Shapes of Interstellar Extinction Curves. V. The IR-Through-UV Curve Morphology
• Gas-to-Dust mass ratios in local galaxies over a 2 dex metallicity range
• Photodissociation and photoionisation of atoms and molecules of astrophysical interest
• Investigating the Cosmic-Ray Ionization Rate in the Galactic Diffuse Interstellar Medium through Observations of H3+
• Herschel Survey of Galactic OH+, H2O+, and H3O+: Probing the Molecular Hydrogen Fraction and Cosmic-Ray Ionization Rate
• The Distribution of Thermal Pressures in the Interstellar Medium from a Survey of C I Fine-Structure Excitation
• HI-to-H2 Transitions and H I Column Densities in Galaxy Star-Forming Regions
• Molecular hydrogen in high-redshift Damped Lyman-alpha systems: The VLT/UVES database
• The Chemistry of Interstellar OH+, H2O+, and H3O+: Inferring the Cosmic Ray Ionization Rates from Observations of Molecular Ions
• The VLT-UVES survey for molecular hydrogen in high-redshift damped Lyman-alpha systems: Physical conditions in the neutral gas
• First detection of CO in a high-redshift DLA
• A translucent interstellar cloud at z=2.69: CO, H2 and HD in the line-of-sight to SDSS J123714.60+064759.5
• Chemical Rates on Small Grains and PAHs: C^+ Recombination and H_2 Formation
• Physical conditions in QSO absorbers from fine-structure absorption lines
• Analytic HI-to-H2 Photodissociation Transition Profiles
• Thermal Phases of the Neutral Atomic Interstellar Medium -- from Solar Metallicity to Primordial Gas
• Discovery of a Perseus-like cloud in the early Universe: HI-to-H2 transition, carbon monoxide and small dust grains at zabs=2.53 towards the quasar J0000+0048
• Excitation mechanisms in newly discovered H2-bearing Damped Lyman-alpha clouds: systems with low molecular fractions
• CO-dark molecular gas at high redshift: very large H${}_2$ content and high pressure in a low metallicity damped Lyman-alpha system
• Understanding Physical Conditions in High Redshift Galaxies through C I Fine Structure Lines: Data and Methodology
• HD molecules at high redshift: A low astration factor of deuterium in a solar-metallicity DLA system at z=2.418
• Partial coverage of the Broad Line Region of Q1232+082 by an intervening H2-bearing cloud
• VLT/UVES observations of extremely strong intervening damped Lyman-alpha systems: Molecular hydrogen and excited carbon, oxygen and silicon at log N(HI)=22.4
• Metallicities, dust and molecular content of a QSO-Damped Lyman-α system reaching log N (H i) = 22: An analog to GRB-DLAs
• Spotting high-z molecular absorbers using neutral carbon: Results from a complete spectroscopic survey with the VLT
• HD/H2 Molecular Clouds in the Early Universe: The Problem of Primordial Deuterium
• X-shooter observations of strong H${}_2$-bearing DLAs at high redshift
• HD molecules at high redshift: The absorption system at z=2.3377 towards Q 1232+082
• METAL: The Metal Evolution, Transport, and Abundance in the Large Magellanic Cloud Hubble program. I. Overview and Initial Results
• Molecular gas and star formation in an absorption-selected galaxy: Hitting the bull's eye at z = 2.46
• Proximate Molecular Quasar Absorbers: Excess of damped H2 systems at zabs~zQSO in SDSS DR14
• Ionization corrections in a multi-phase interstellar medium: Lessons from a z~2 sub-DLA
• Neutral chlorine and molecular hydrogen at high redshift
• Physical conditions in diffuse interstellar medium of local and high redshift galaxies: measurements based on excitation of H${}_2$ rotational and CI fine-structure levels
• HD molecules at high redshift: cosmic-ray ionization rate in the diffuse interstellar medium
• Down-the-barrel observations of a multiphase quasar outflow at high redshift: VLT/X-shooter spectroscopy of the proximate molecular absorber at z=2.631 towards SDSS J001514+184212
• HD/H${}_2$ ratio in the diffuse interstellar medium
• Nature of the DLA towards Q0528-250: High pressure and strong UV field revealed by excitation of CI, H2 and SiII
• Estimation of physical conditions in the cold phase of the ISM in the sub-DLA system at z = 2.06 in the spectrum of the quasar J2123-0050
• OH in the diffuse interstellar medium: physical modelling and prospects with upcoming SKA precursor/pathfinder surveys
• Proximate molecular quasar absorbers: Chemical enrichment and kinematics of the neutral gas
• CII*/CII ratio in high-redshift DLAs: ISM phase separation drives the observed bimodality of [CII] cooling rates
• Cold diffuse interstellar medium of Magellanic Clouds: II. Physical conditions from excitation of CI and H${}_2$

Cited by in corpus (2)

• Quasar radiation transforms the gas in a merging companion galaxy
• One H2 molecule per ten million H-atoms reveals sub-pc scale cold overdensities at z~4