Physical conditions in two high-redshift H${}_2$-bearing GRB-DLAs, 120815A and 121024A

Abstract

The gamma-ray burst (GRB) afterglows provide an unique opportunity to study the interstellar medium (ISM) of star-forming galaxies at high-redshift. The GRB-DLAs (damped Lyman-$\alpha$ absorbers) contain a large neutral hydrogen column density, N(H I), and are observed against the GRB afterglow. A large fraction of GRB-DLAs show presence of molecular hydrogen (H${}_2$) which is an indicator of star-formation. Hence it is important to study those GRB-DLAs which have H${}_2$ lines to decipher and understand their physical conditions. The GRB-DLAs 121024A and 120815A, situated at redshift 2.30 and 2.36 respectively, are two such important H${}_2$-bearing GRB-DLAs. Besides H${}_2$, these two GRB-DLAs also show many metal lines. In this work we have carried out a detail numerical study on the H${}_2$ lines, as well as on those metal lines, in GRB-DLAs 121024A and 120815A self-consistently. We use the spectral synthesis code CLOUDY for this study. This modeling helps us to determine the underlying physical conditions which give rise such lines and hence to understand these two GRB-DLAs in much more detail than any other previous investigation. We find that the hydrogen densities for these two H${}_2$-bearing DLAs are $\ge$ 60 cm${}^{-3}$. Moreover our study infers that the linear sizes are $\le 17.7$ pc for these two GRB-DLAs, and the mean gas temperatures averaged over the cloud thickness, are $\le$ 140 K.

arXiv comment10 pages, 5 figures, 6 tables. Accepted for publication in MNRAS

References in corpus (48)

• The Star Formation Law in Nearby Galaxies on Sub-Kpc Scales
• Radiative transfer in a clumpy universe: IV. New synthesis models of the cosmic UV/X-ray background
• Structure of Stationary Photodissociation Fronts
• Damped Lyman alpha Systems
• The 2013 Release of Cloudy
• The VLT-UVES survey for molecular hydrogen in high-redshift damped Lyman-alpha systems
• H3+ in Diffuse Interstellar Clouds: a Tracer for the Cosmic-Ray Ionization Rate
• Probing the ISM Near Star Forming Regions with GRB Afterglow Spectroscopy: Gas, Metals, and Dust
• HI-to-H2 Transitions and H I Column Densities in Galaxy Star-Forming Regions
• The UCSD HIRES/KeckI Damped Lya Abundance Database: II. The Implications
• The VLT-UVES survey for molecular hydrogen in high-redshift damped Lyman-alpha systems: Physical conditions in the neutral gas
• Reconciling the Metallicity Distributions of Gamma-ray Burst, Damped Lyman-alpha, and Lyman-break Galaxies at z=3
• The UCSD HIRES/KeckI Damped Lya Abundance Database: I. The Data
• Molecular Hydrogen in Star-forming regions: implementation of its micro-physics in Cloudy
• Numerical simulations of conversion to Alfven waves in sunspots
• Grain size distributions and photo-electric heating in ionized media
• Physical conditions in high-redshift GRB-DLA absorbers observed with VLT/UVES: Implications for molecular hydrogen searches
• Molecular Hydrogen in the Damped Lyman-alpha System towards GRB 120815A at z=2.36
• A connection between extremely strong Damped Lyman-alpha Systems and Lyman-alpha Emitting Galaxies at small impact parameters
• Molecular Hydrogen in the Damped Ly alpha Absorber of Q1331+170
• The warm, the excited, and the molecular gas: GRB 121024A shining through its star-forming galaxy
• Excitation mechanisms in newly discovered H2-bearing Damped Lyman-alpha clouds: systems with low molecular fractions
• Unveiling the Secrets of Metallicity and Massive Star Formation Using DLAs along Gamma-ray Bursts
• Implications of 21cm observations for damped Ly-$\alpha$ systems
• VLT/X-shooter spectroscopy of the GRB 120327A afterglow
• Distribution and kinematics of atomic and molecular gas inside the Solar circle
• Missing Molecular Hydrogen and the Physical Conditions of GRB Host Galaxies
• Evidence for diffuse molecular gas and dust in the hearts of gamma-ray burst host galaxies
• 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
• Molecular hydrogen absorption systems in Sloan Digital Sky Survey
• Spotting high-z molecular absorbers using neutral carbon: Results from a complete spectroscopic survey with the VLT
• Constraining the H${}_2$ column density distribution at z$\sim$3 from composite DLA spectra
• On the enhanced cosmic-ray ionization rate in the diffuse cloud towards Zeta Persei
• The Molecular Hydrogen Deficit in Gamma-Ray Burst Afterglows
• Direct Evidence of Cold Gas in DLA 0812+32B
• Molecular gas and star formation in an absorption-selected galaxy: Hitting the bull's eye at z = 2.46
• VLT/X-shooter spectroscopy of the afterglow of the Swift GRB 130606A: Chemical abundances and reionisation at $z\sim 6$
• The Discovery of Vibrationally-Excited H_2 in the Molecular Cloud near GRB 080607
• Thermal Pressures in the Interstellar Medium of the Magellanic Clouds
• Physical conditions in the ISM towards HD185418
• A Large Catalogue of Multi-wavelength GRB Afterglows I: Color Evolution And Its Physical Implication
• Cold gas in the early Universe. Survey for neutral atomic-carbon in GRB host galaxies at 1 < z < 6 from optical afterglow spectroscopy
• Physical conditions in three high-z H2-bearing DLAs: implications for grain size
• Multicomponent H2 in DLA at zabs = 2.05: physical conditions through observations and numerical models
• The validity of 21 cm spin temperature as a kinetic temperature indicator in atomic and molecular gas
• Chemical enrichment and host galaxies of extremely-strong intervening DLAs towards quasars
• Exploring Damped Lyman-$\alpha$ System Host Galaxies using Gamma-ray Bursts
• Spectroscopic modelling of four neutron star low-mass X-ray binaries using CLOUDY

Cited by in corpus (5)

• No escaping helium from 55 Cnc e
• 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
• Probing the tidal disruption event iPTF16axa with CLOUDY and disc-wind models
• Multi-phase gas properties of extremely strong intervening DLAs towards quasars
• Detecting PAHs in high-z galaxies in proxy: Modelling physical conditions in an extremely strong damped Lyman-alpha absorber towards QSO SDSS J1143+1420 at z=2.323