Physical conditions in the neutral interstellar medium at 
<i>z</i> = 2.43 toward Q 2348-011

Noterdaeme, P.; Petitjean, P.; Srianand, R.; Ledoux, C.; Petit, Franck

doi:10.1051/0004-6361:20066897

Cited by 68 publications

(64 citation statements)

References 53 publications

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“…Ledoux et al (2015) have measured the equivalent widths of the λ1560 and λ1656 C I multiplets for 66 systems found in a sample of low-resolution (R∼2000) Sloan Digital Sky Survey spectra of 41,696 quasars-but higher-resolution spectra will be needed to determine accurate column densities and to assess the fine-structure excitation in those systems. Moderately high resolution spectra (mostly from Keck/HIRES and/or VLT/UVES) have yielded detections of C I in a smaller number of systems, and fits to the line profiles have yielded column densities for the ground and excited fine-structure states for the "individual" components discernible in the spectra (Quast et al 2002;Srianand et al 2005Srianand et al , 2008Noterdaeme et al 2007bNoterdaeme et al , 2010Noterdaeme et al , 2015Jorgenson et al 2010;Carswell et al 2011;Ma et al 2015). Srianand et al (2005) performed a simplified analysis of the C I excitation for components in eight systems (considering only collisions with atomic hydrogen and generally assuming T=100 K) and found somewhat higher pressures than those typically found in the local Galactic ISM.…”

Section: I In Qso Absorption-line Systemsmentioning

confidence: 99%

Thermal Pressures in the Interstellar Medium of the Magellanic Clouds*

Welty

Lauroesch

Wong

et al. 2016

ApJ

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We discuss the thermal pressures (n H T) in predominantly cold, neutral interstellar gas in the Magellanic Clouds, derived from analyses of the fine-structure excitation of neutral carbon, as seen in high-resolution Hubble Space Telescope/Space Telescope Imaging Spectrograph spectra of seven diverse sight lines in the LMC and SMC. Detailed fits to the line profiles of the absorption from C I, C I * , and C I ** yield consistent column densities for the three to six C I multiplets detected in each sight line. In the LMC and SMC, N(C I tot ) is consistent with Galactic trends versus N(Na I) and N(CH), but is slightly lower versus N(K I) and N(H 2 ). As for N(Na I) and N(K I), N(C I tot ) is generally significantly lower, for a given N(H tot ), in the LMC and (especially) in the SMC, compared to the local Galactic relationship. For the LMC and SMC components with well-determined column densities for C I, C I * , and C I ** , the derived thermal pressures are typically factors of a few higher than the values found for most cold, neutral clouds in the Galactic ISM. Such differences are consistent with the predictions of models for clouds in systems (like the LMC and SMC) that are characterized by lower metallicities, lower dust-to-gas ratios, and enhanced radiation fields-where higher pressures are required for stable cold, neutral clouds. The pressures may be further enhanced by energetic activity (e.g., due to stellar winds, star formation, and/or supernova remnants) in several of the regions probed by these sight lines. Comparisons are made with the C I observed in some quasar absorption-line systems.

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Section: I In Qso Absorption-line Systemsmentioning

confidence: 99%

Thermal Pressures in the Interstellar Medium of the Magellanic Clouds*

Welty

Lauroesch

Wong

et al. 2016

ApJ

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“…The balance of these formation and destruction processes determines the molecular fraction of H 2 , f H 2 ¼ 2N H 2 /(N H i þ 2N H 2 ). Thus, a measurement of f H 2 and relative populations in the various rotational levels of the ground vibrational state can serve as sensitive diagnostics of local physical conditions such as density, temperature, and ambient FUVradiation field (T02; Browning et al 2003;Srianand et al 2005;Noterdaeme et al 2007). For galaxies at z > 2, the LW bands are redshifted into the range of groundbased optical telescopes, and can be found in the spectra of a bright background source.…”

Section: Datamentioning

confidence: 99%

Missing Molecular Hydrogen and the Physical Conditions of GRB Host Galaxies

Tumlinson¹,

Prochaska²,

Chen³

et al. 2007

ApJ

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We examine the abundance of molecular hydrogen ( H 2 ) in the spectra of gamma ray burst afterglows (GRBs). In nearby galaxies, H 2 traces the cold neutral medium (CNM ) and dense molecular star-forming interstellar gas. Although H 2 is detected in at least half of all sight lines toward hot stars in the Magellanic Clouds and in %25% of damped Ly systems toward quasars, it is not detected in any of the five GRB environments with a similar range of neutral hydrogen column density and metallicity. We detect no vibrationally excited H 2 that would imply that the GRB itself has photodissociated its parent molecular cloud, so such models are ruled out unless the parent cloud was P4 pc in radius and was fully dissociated prior to the spectroscopic observations, or the star escaped its parent cloud during its main-sequence lifetime. The low molecular fractions for the GRBs are mysterious in light of their large column densities of neutral H and expectations based on local analogs, i.e., 30 Doradus in the LMC. This surprising lack of H 2 in GRB damped Ly absorbers indicates that the destruction processes that suppress molecule formation in the LMC and SMC are more effective in the GRB hosts, most probably due to a combination of low metallicity and an FUV radiation field 10 Y100 times the Galactic mean field. These inferred conditions place strong constraints on the star-forming regions in these early galaxies.

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“…In particular, the surrounding UV field can be estimated, thereby constraining the instantaneous star formation rates (SFRs), see e.g. Noterdaeme et al (2007), Srianand et al (2005), Wolfe et al (2004). Overall, DLAs are a very important probe of various physical processes that are at play in the formation of galaxies (e.g.…”

Section: Introductionmentioning

confidence: 99%

VLT/UVES observations of extremely strong intervening damped Lyman-αsystems

Noterdaeme

Srianand

Rahmani

et al. 2015

A&A

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We present a detailed analysis of three extremely strong, intervening damped Lyman-α systems (ESDLAs, with log N(H i) ≥ 21.7) observed towards quasars with the Ultraviolet and Visual Echelle Spectrograph on the Very Large Telescope. We measure overall metallicities of [Zn/H] ∼ −1.2, −1.3, and −0.7 at, respectively, z abs = 2.34 towards SDSS J214043.02−032139.2 (log N(H i) = 22.4 ± 0.1), z abs = 3.35 towards SDSS J145646.48+160939.3 (log N(H i) = 21.7 ± 0.1), and z abs = 2.25 towards SDSS J015445.22+193515.8 (log N(H i) = 21.75 ± 0.15). Iron depletion of about a factor 15 compared to volatile elements is seen in the DLA towards J2140−0321, while the other two show deletion that is typical of known DLAs. We detect H 2 towards J2140−0321 (log N(H 2 ) = 20.13 ± 0.07) and J1456+1609 (log N(H 2 ) = 17.10 ± 0.09) and argue for a tentative detection towards J0154+1935. Absorption from the excited fine-structure levels of O i, C i, and Si ii are detected in the system towards J2140−0321, which has the largest H i column density detected so far in an intervening DLA. This is the first detection of O i fine-structure lines in a QSO-DLA, which also provides us with a rare possibility to study the chemical abundances of less abundant atoms like Co and Ge. Simple single-phase photo-ionisation models fail to reproduce all the observed quantities. Instead, we suggest that the cloud has a stratified structure: H 2 and C i most likely stem from a dense (log n H ∼ 2.5−3) and cold (80 K) phase and from a warm (250 K) phase. They contain a fraction of the total H i, while a warmer (T > 1000 K) phase probably contributes significantly to the high excitation of O i fine-structure levels. The observed C i/H 2 column density ratio is surprisingly low compared to model predictions, and we do not detect CO molecules: this suggests a possible underabundance of C by 0.7 dex compared to other alpha elements. The absorber could be a photo-dissociation region close to a bright star (or a star cluster) where higher temperature occurs in the illuminated region. Direct detection of on-going star formation through e.g. near-infrared emission lines in the surroundings of the gas would enable a detailed physical modelling of the system.

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Physical conditions in the neutral interstellar medium at z = 2.43 toward Q 2348-011

Cited by 68 publications

References 53 publications

Thermal Pressures in the Interstellar Medium of the Magellanic Clouds*

Thermal Pressures in the Interstellar Medium of the Magellanic Clouds*

Missing Molecular Hydrogen and the Physical Conditions of GRB Host Galaxies

VLT/UVES observations of extremely strong intervening damped Lyman-αsystems

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