The nature of $\ion{N}{v}$ absorbers at high redshift

Fechner, C.; Richter, Philipp

doi:10.1051/0004-6361/200810421

Cited by 20 publications

(41 citation statements)

References 106 publications

(185 reference statements)

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“…(a) the median N v line width in DLAs b = 18 km s −1 is three times broader than the median reported by Fechner & Richter (2009) in the (photoionized) IGM; (b) collisional ionization models for plasma at log T = 5.2−5.4 can reproduce (when corrected for the non-solar elemental abundance ratios present in DLAs) the observed integrated high-ion column density ratios in the majority of DLAs in our sample; (c) there is no evidence for an enhanced N v detection rate in DLAs between 500 and 5000 km s −1 from the QSO, as would be expected if the N v was predominantly photoionized. 7.…”

Section: Discussionmentioning

confidence: 65%

“…High-redshift (z ≈ 2−3) N v absorption is found in several environments, including the intergalactic medium (Bergeron et al 2002;Carswell et al 2002;Simcoe et al 2002;Boksenberg et al 2003;Simcoe et al 2006;Schaye et al 2007;Fechner & Richter 2009), quasar-intrinsic or "associated" systems (Hamann 1997;Petitjean & Srianand 1999;D'Odorico et al 2004;Fechner et al 2004;Fechner & Richter 2009;Fox et al 2008a), LBGs (Pettini et al 2002b;Shapley et al 2003), and gamma-ray burst (GRB) host galaxies (Prochaska et al 2008c;Fox et al 2008b;7 Whether or not the H ii columns derived from N v and O vi should be summed depends on whether the two lines trace the same regions.…”

Section: Discussionmentioning

confidence: 99%

“…This further supports the idea that these two ions trace the same regions of gas. Note that one can always add extra components to any Voigt-profile fit, and the effect of this is to shift the distribution measured by Fechner & Richter (2009) in their survey for (intergalactic) N v absorption at high redshift. We discuss the implications of this in Sect.…”

Section: Relationship Between N V and Other High Ionsmentioning

confidence: 99%

“…Indeed, Fechner & Richter (2009) report that the fraction of C iv systems showing N v rises from 11% for intervening absorbers to 37% for proximate absorbers (see also Hamann 1997;D'Odorico et al 2004). One possible explanation for our apparent lack of a proximity effect in DLA N v 9 is that the expected QSO sphere-of-influence (the region in which the QSO radiation density exceeds the extragalactic background density) extends over only ∼1500−2500 km s −1 at z ≈ 2.5, not 5000 km s −1 .…”

Section: The N V Detection Rate In Dlasmentioning

confidence: 99%

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Metal-enriched plasma in protogalactic halos

Fox¹,

Prochaska

Ledoux³

et al. 2009

A&A

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We continue our recent work of characterizing the plasma content of high-redshift damped and sub-damped Lyman-α systems (DLAs/sub-DLAs), which represent multi-phase gaseous (proto)galactic disks and halos seen toward a background source. We survey N v absorption in a sample of 91 DLAs and 18 sub-DLAs in the redshift range 1.67 < z abs < 4.28 with unblended coverage of the N v doublet. Our dataset includes high-resolution (6−8 km s are required to keep the cloud sizes physically reasonable. The nature of the remaining ≈80% of (broad) N v components is unclear; models of radiatively-cooling collisionally-ionized plasma at log (T /K) = 5.2−5.4 are fairly successful in reproducing the observed integrated high-ion column density ratios and the component line widths, but we cannot rule out photoionization by local sources.Finally, we identify several unusual DLAs with extremely low metallicity (<0.01 solar) but strong high-ion absorption (log N(N v) > 14 or log N(O vi) > 14.2), which present challenges to either galactic inflow or outflow models.

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Section: Discussionmentioning

confidence: 65%

Section: Discussionmentioning

confidence: 99%

Section: Relationship Between N V and Other High Ionsmentioning

confidence: 99%

Section: The N V Detection Rate In Dlasmentioning

confidence: 99%

See 2 more Smart Citations

Metal-enriched plasma in protogalactic halos

Fox¹,

Prochaska

Ledoux³

et al. 2009

A&A

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“…Carbon -Previous studies of intervening absorbers with achievable carbon measurements have observed an underabundance of carbon compared to α-elements (Fechner & Richter 2009;Pettini et al 2008;Erni et al 2006;Richter et al 2005). This is expected from modelling (e.g.…”

Section: Abundances From Ion Ratiosmentioning

confidence: 86%

VLT/UVES observations of peculiarαabundances in a sub-DLA atz≈ 1.8 towards the quasar B1101−26

Fox¹,

Richter²,

Fechner³

2014

A&A

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We present a detailed analysis of chemical abundances in a sub-damped Lyman α absorber at z = 1.839 towards the quasar B1101−26, based on a very-high-resolution (R ∼ 75 000) and high-signal-to-noise (S /N > 100) spectrum observed with the UV Visual Echelle spectrograph (UVES) installed on the ESO Very Large Telescope (VLT). The absorption line profiles are resolved into a maximum of eleven velocity components spanning a rest-frame velocity range of ≈200 km s −1 . Detected ions include C , We calculate detailed photoionisation models for two subcomponents with Cloudy, and can rule out that ionisation effects alone are responsible for the high S/O ratio. We instead speculate that the high S/O ratio is caused by the combination of several effects, such as specific ionisation conditions in multi-phase gas, unusual relative abundances of heavy elements, and/or dust depletion in a local gas environment that is not well mixed and/or that might be related to star-formation activity in the host galaxy. We discuss the implications of our findings for the interpretation of α-element abundances in metal absorbers at high redshift.

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Metal-rich absorbers at high redshifts: abundance patterns

Levshakov

Agafonova²,

Molaro

et al. 2009

A&A

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Aims. To study chemical composition of metal-rich absorbers at high redshifts in order to understand their nature and to determine sources of their metal enrichment. Methods. From six spectra of high-z QSOs, we select eleven metal-rich, Z > ∼ Z , and optically-thin to the ionizing radiation, N(H i) < 10 17 cm −2 , absorption systems ranging between z = 1.5 and z = 2.9 and revealing lines of different ions in subsequent ionization stages. Computations are performed using the Monte Carlo inversion (MCI) procedure complemented with the adjustment of the spectral shape of the ionizing radiation. This procedure along with selection criteria for the absorption systems guarantee the accuracy of the ionization corrections and of the derived element abundances (C, N, O, Mg, Al, Si, Fe).Results. The majority of the systems (10 from 11) show abundance patterns which relate them to outflows from low and intermediate mass stars. One absorber is enriched prevalently by SNe II, however, a low percentage of such systems in our sample is conditioned by the selection criteria. All systems have sub-kpc linear sizes along the line-of-sight with many less than ∼20 pc. In several systems, silicon is deficient, presumably due to the depletion onto dust grains in the envelopes of dust-forming stars and the subsequent gasdust separation. At any value of [C/H], nitrogen can be either deficient, [N/C] < 0, or enhanced, [N/C] > 0, which supposes that the nitrogen enrichment occurs irregularly. In some cases, the lines of Mg ii λλ2796, 2803 appear to be shifted, probably as a result of an enhanced content of heavy isotopes 25 Mg and 26 Mg in the absorbing gas relative to the solar isotopic composition. Seven absorbers are characterized by low mean ionization parameter U, log U < −2.3, among them only one system has a redshift z > 2 (z abs = 2.5745) whereas all others are found at z ∼ 1.8. This statistics is not affected by any selection criteria and reflects the real rise in number of such systems at z < 2.0. Comparing the space number density of metal-rich absorbers with the comoving density of star-forming galaxies at z ∼ 2, we estimate that the circumgalactic volume of each galaxy is populated by ∼10 7 −10 8 such absorbers with total mass < ∼ 1/100th of the stellar galactic mass. Possible effects of high metal content on the peak values of star-forming and AGN activities at z ∼ 2 are discussed.

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The nature of $\ion{N}{v}$ absorbers at high redshift

Cited by 20 publications

References 106 publications

Metal-enriched plasma in protogalactic halos

Metal-enriched plasma in protogalactic halos

VLT/UVES observations of peculiarαabundances in a sub-DLA atz≈ 1.8 towards the quasar B1101−26

Metal-rich absorbers at high redshifts: abundance patterns

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