A Near‐Solar Metallicity, Nitrogen‐deficient Lyman Limit Absorber Associated with Two S0 Galaxies

Jenkins, Edward B.; Bowen, David V.; Tripp, Todd M.; Sembach, Kenneth R.

doi:10.1086/428878

Cited by 60 publications

(92 citation statements)

References 131 publications

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“…Hamann & Ferland 1999), but at Z ∼ Z still deficit of nitrogen, [N/C] < 0, is measured (e.g. Srianand & Petitjean 2001;Reimers et al 2005a;Jenkins et al 2005). In principle, we cannot exclude a possibility that the present system is out of equilibrium and N v is still overionized (i.e.…”

Section: Absorption Systems Towards Hs 1700+6416mentioning

confidence: 86%

Spectral shape of the UV ionizing background and He II absorption at redshifts 1.8 < z < 2.9

Agafonova

Levshakov

Reimers

et al. 2006

A&A

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Aims. The shape of the UV ionizing background is reconstructed from optically thin metal absorption-line systems identified in spectra of HE 2347-4342, Q 1157+3143, and HS 1700+6416 in the redshift interval 1.8 < z < 2.9. Methods. The systems are analyzed by means of the Monte Carlo Inversion method completed with the spectral shape recovering procedure.Results. The UVB spectral shape fluctuates at 2.4 < z < 2.9 mostly due to radiative transfer processes in the clumpy IGM. At z < ∼ 1.8, the IGM becomes almost transparent both in the H i and He ii Lyman continua and the variability of the spectral shape comes from diversity of spectral indices describing the QSO/AGN intrinsic radiation. At z > 2.4, the recovered spectral shapes show intensity depression between 3 and 4 Ryd due to He ii Lyα absorption in the IGM clouds (line blanketing) and continuous medium (true Gunn-Petersen effect). The mean He ii Lyα opacity estimated from the depth of this depression corresponds within 1−2σ to the values directly measured from the H i/He ii Lyα forest towards the quasars studied. The observed scatter in η = N(He ii)/N(H i) and anti-correlation between N(H i) and η can be explained by the combined action of variable spectral softness and differences in the mean gas density between the absorbing clouds. Neither of the recovered spectral shapes show features which can be attributed to the putative input of radiation from soft sources like starburst galaxies.

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Section: Absorption Systems Towards Hs 1700+6416mentioning

confidence: 86%

Spectral shape of the UV ionizing background and He II absorption at redshifts 1.8 < z < 2.9

Agafonova

Levshakov

Reimers

et al. 2006

A&A

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“…However, nitrogen measurements in planetary nebulae show that even at high metallicities nitrogen can be both under-and overabundant (Aller & Czyzak 1983;Perinotto 1991;Richer & McCall 2008). Low ratios [N/C] < 0 at near-solar metallicities were reported also for intergalactic absorbers by Reimers et al (2005) and Jenkins et al (2005).…”

Section: Analysis Of Individual Systemsmentioning

confidence: 99%

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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“…Thus, Ly absorbers in a single quasar spectrum probe density perturbations across a wide range of scales, from voids to groups of galaxies. Metal absorbers provide complementary information about the abundances, kinematics, and ionization conditions near galaxy halos and in the intergalactic medium (IGM; e.g., Bowen et al 1995;Davé et al 1998;Chen & Prochaska 2000;Tripp et al 2001Tripp et al , 2002Tripp et al , 2005Rosenberg et al 2003;Shull et al 2003;Tumlinson et al 2005;Keeney et al 2005;Jenkins et al 2005). Metal systems also give indications about the strength of feedback from supernovae in galaxies and, in the case of O vi absorbers, can contain large reservoirs of baryons at both low and high redshift (e.g., Tripp et al 2000;Savage et al 2002;Carswell et al 2002;Simcoe et al 2004;cf.…”

Section: à2mentioning

confidence: 99%

The Low‐Redshift Lyα Forest toward PKS 0405−123

Williger

Heap

Weymann³

et al. 2006

ApJ

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We present results for Ly forest and metal absorbers from $7 km s À1 resolution Space Telescope Imaging Spectrograph data for QSO PKS 0405À123 (z ¼ 0:574). We analyze strong and weak samples of Ly forest lines, containing 60 absorbers with column density log N H i ! 13:3 over 0:002 < z < 0:423 and 44 with log N H i ! 13:1 over 0:020 < z < 0:234, respectively. Seven absorbers contain metals, all with associated O vi and often offset in velocity from Ly. The strong and weak Doppler parameter distributions have hbi ¼ 47 AE 22 and 44 AE 21 km s À1 , respectively. Simulated spectra suggest that line blending and signal-to-noise ratio effects inflate b. For absorbers with 13:1 < log N H i < 14:0, we find a redshift overdensity of $0.2-0.3 dex at 0:127 < z < 0:234, which we attribute to cosmic variance. There is a void in the strong sample at 0:0320 < z < 0:0814 with probability of random occurrence P < 0:0004. We detect Ly-Ly clustering in our sample on a scale of Áv 250 km s À1 for log N H i ! 13:3, consistent with a numerical model of structure evolution. We detect velocity correlations of up to 250 km s À1 between Ly absorbers and 39 galaxies at z < 0:43 out to a transverse distance of 1.6 h À1 70 local frame Mpc. The Ly-galaxy two-point correlation function is significant out to Áv < 250 km s À1 and grows with minimum H i column density. The strongest signal occurs for log N H i k13:5 14:0 absorbers and is similar to the galaxy-galaxy correlation, implying that such Ly absorbers have masses log (M /M ) ¼ 11:3 þ1:0 À0:6 . We find a correlation between local galaxy counts and local summed H i column density, with peak significance on scales of 4000-6000 km s À1 and probability of random occurrence P ¼ 0:0009. Finally, we present column densities for a number of Galactic species.

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A Near‐Solar Metallicity, Nitrogen‐deficient Lyman Limit Absorber Associated with Two S0 Galaxies

Cited by 60 publications

References 131 publications

Spectral shape of the UV ionizing background and He II absorption at redshifts 1.8 < z < 2.9

Spectral shape of the UV ionizing background and He II absorption at redshifts 1.8 < z < 2.9

Metal-rich absorbers at high redshifts: abundance patterns

The Low‐Redshift Lyα Forest toward PKS 0405−123

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