The Ly<i>α</i>forest at $\mathsf{1.5 &lt; {\vec z} &lt; 4}$

Kim, T.-S.; Cristiani, S.; D’Odorico, S.

doi:10.1051/0004-6361:20010650

Cited by 119 publications

(211 citation statements)

References 82 publications

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“…The values of the K-S probability show that the power law is an excellent approximation of the distribution of lines at the redshift range covered in our sample. Note that this disagrees with the result of Kim, Cristiani, & D'Odorico (2001), who found that the break in dN=dz slope occurred around z $ 1:2.…”

Section: The Methodscontrasting

confidence: 99%

“…Analyses of high-redshift data (Petitjean et al 1993;Press & Rybicki 1993;Hu et al 1995;Dobrzycki & Bechtold 1996;Kim et al 2001) showed that the value of is in the 1.4-1.7 range. Analysis of low-redshift data from HST/GHRS (Penton et al 2000) indicated near the high end of this range, at 1.7-1.8.…”

Section: Line Equivalent Width and Neutral Hydrogen Column Density DImentioning

confidence: 99%

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A Uniform Analysis of the Lyα Forest atz= 0–5. IV. The Clustering and Evolution of Clouds atz≤ 1.7

Dobrzycki

Bechtold

Scott

et al. 2002

ApJ

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We present results on the evolution and clustering of Ly lines at low redshift as part of our series '' A Uniform Analysis of the Ly Forest at z ¼ 0 5.'' The sample analyzed in this paper contains 1298 Ly absorption lines from 165 quasar spectra mined from the archives of the Faint Object Spectrograph on the Hubble Space Telescope (HST). Our sample extends to z % 1:7, slightly higher than the sample analyzed by the HST Quasar Absorption Line Key Project. We confirm the result from the Key Project that the number density evolution of Ly lines at low redshifts can be described by a power law that is significantly flatter than that found at high z. We find that the evolution is somewhat steeper than obtained previously. Specifically, we find ¼ 0:54 AE 0:21 for lines with equivalent widths greater than 0.24 Å and ¼ 0:60 AE 0:14 using a variable equivalent width threshold. We find that the difference between our and Key Project results is likely attributable to different redshift coverage of the two samples. The results concerning the number density evolution are not significantly affected if one includes Ly lines which are members of metal systems. Object-to-object fluctuations in the number of lines detected are small, indicating a high degree of uniformity in the intergalactic medium on large scales. We find marginal evidence that weak and strong lines undergo different evolution. We find weak clustering for Ly lines at velocity separations DV 500 km s À1 , weaker than the level predicted from an earlier analysis by Ulmer of a small subsample of the Key Project data. We see no correlations for metal system-Ly forest or extensive metal system-Ly forest combinations.

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Section: The Methodscontrasting

confidence: 99%

Section: Line Equivalent Width and Neutral Hydrogen Column Density DImentioning

confidence: 99%

A Uniform Analysis of the Lyα Forest atz= 0–5. IV. The Clustering and Evolution of Clouds atz≤ 1.7

Dobrzycki

Bechtold

Scott

et al. 2002

ApJ

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“…The result from the HST/FOS Quasar Absorption Line Key project shows such a slow change in the dn/dz evolution at z < 1.5 (Weymann et al 1998), compared to a much steeper dn/dz evolution shown at z > 2 ( Kim et al 1997Kim et al , 2001Kim et al , 2002. Cosmic variance also seems to increase at lower z .…”

Section: Introductionmentioning

confidence: 91%

The evolution of H i and C iv quasar absorption line systems at 1.9 <z< 3.2

Kim

Partl

Carswell

et al. 2013

A&A

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104

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We have investigated the distribution and evolution of ∼3100 intergalactic neutral hydrogen (H i) absorbers with H i column densities log N H i = [12.75, 17.0] at 1.9 < z < 3.2, using 18 high resolution, high signal-to-noise quasar spectra obtained from the ESO VLT/UVES archive. We used two sets of Voigt profile fitting analysis, one including all the available high-order Lyman lines to obtain reliable H i column densities of saturated lines, and another using only the Lyα transition. There is no significant difference between the Lyα-only fit and the high-order Lyman fit results. Combining our Lyα-only fit results at 1.7 < z < 3.6 with high-quality literature data, the mean number density at 0 < z < 4 is not well described by a single power law and strongly suggests that its evolution slows down at z ≤ 1.5 at the high and low column density ranges. We also divided our entire H i absorbers at 1.9 < z < 3.2 into two samples, the unenriched forest and the C iv-enriched forest, depending on whether H i lines are associated with C iv at log N C iv ≥ 12.2 within a given velocity range. The entire H i column density distribution function (CDDF) can be described as the combination of these two well-characterised populations which overlap at log N H i ∼ 15. At log N H i ≤ 15, the unenriched forest dominates, showing a similar power-law distribution to the entire forest. The C iv-enriched forest dominates at log N H i ≥ 15, with its distribution function as ∝N ∼−1.45. However, it starts to flatten out at lower N H i , since the enriched forest fraction decreases with decreasing N H i . The deviation from the power law at log N H i = [14, 17] shown in the CDDF for the entire H i sample is a result of combining two different H i populations with a different CDDF shape. The total H i mass density relative to the critical density is Ω H i ∼ 1.6 × 10 −6 h −1 , where the enriched forest accounts for ∼40% of Ω H i .

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“…The data reduction and analysis for HE 2217À2818 have been described by Kim, Cristiani, & D'Odorico (2001), who also show part of the spectrum. Some spectral regions and results for HE 1122À1648 are described by Kim et al (2002).…”

Section: Observations and Absorption Line Fitsmentioning

confidence: 99%

The Enrichment History of the Intergalactic Medium: Oviin Lyα Forest Systems at Redshiftz ∼ 2

Carswell

Schaye

Kim

2002

ApJ

140

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A search for O vi 1031.93, 1037.62 Å at redshifts corresponding to Ly lines in the z em $ 2:4 QSOs HE 1122À1648 and HE 2217À2818 reveals that a substantial fraction of those with H i column densities log NðH iÞ > 14:0 (cm À2 ) are highly ionized and show some heavy-element enrichment. If these two sight lines are typical, then the O vi systems contain a cosmologically significant fraction of the baryons and the metals in the universe. For most systems the temperatures derived from the line widths are too low for collisional ionization to be responsible for the O vi lines. Photoionization models with a substantial hard UV flux can reproduce observations for densities that are in good agreement with a model assuming local, hydrostatic equilibrium and heavy-element abundances in the range $10 À3 to 10 À2 solar. Photoionization by a UV flux much softer than that predicted by Haardt & Madau for a background dominated by quasars can be ruled out. Finally, we find one system with a very low H i column density for which both photoionization and collisional ionization models yield a metallicity close to solar and a density that is inconsistent with gravitational confinement, unless the gas fraction is negligible.

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The Lyαforest at $\mathsf{1.5 < {\vec z} < 4}$

Cited by 119 publications

References 82 publications

A Uniform Analysis of the Lyα Forest atz= 0–5. IV. The Clustering and Evolution of Clouds atz≤ 1.7

A Uniform Analysis of the Lyα Forest atz= 0–5. IV. The Clustering and Evolution of Clouds atz≤ 1.7

The evolution of H i and C iv quasar absorption line systems at 1.9 <z< 3.2

The Enrichment History of the Intergalactic Medium: Oviin Lyα Forest Systems at Redshiftz ∼ 2

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