The Enrichment History of the Intergalactic Medium: O<scp>vi</scp>in Lyα Forest Systems at Redshift<i>z</i> ∼ 2

Carswell, Bob; Schaye, Joop; Kim, Tae-Sun

doi:10.1086/342404

Cited by 89 publications

(156 citation statements)

References 23 publications

Supporting

Mentioning

140

Contrasting

Order By: Relevance

“…In order to obtain the absorption line parameters (the redshift z, the column density N in cm −2 and the Doppler parameter b in km s −1 ), we have performed a Voigt profile fitting analysis using VPFIT 1 . Details can be found in the documentation provided with the software, Carswell, Schaye & Kim (2002) and Kim et al (2007). Here, we only give a brief description of the fitting procedure.…”

Section: Data and Voigt Profile Fittingmentioning

confidence: 99%

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

104

View full text Add to dashboard Cite

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 .

show abstract

Section: Data and Voigt Profile Fittingmentioning

confidence: 99%

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

104

View full text Add to dashboard Cite

show abstract

“…Because O vi is placed within the Ly , Ly , and higher order Lyman forests, our first step has been to follow the procedure of Carswell et al (2002), fitting the entire Ly forest region to remove high-order H i transitions from the data. Beginning at the emission redshift of the quasar, each H i line in the forest was fitted with a combination of Voigt profiles using the VPFIT 6 software package.…”

Section: Identification and Measurement Of The O VI Systemsmentioning

confidence: 99%

“…However, Schaye et al (2000) have claimed a detection of O vi even at very low densities, reaching below the cosmic mean. More recently Carswell, Schaye, & Kim (2002) and Bergeron et al (2002) have discovered evidence for O vi enrichment in a number of individual systems with N H i $ 10 14:5 at z $ 2:3. This paper expands upon these studies by using an increased number of sight lines observed at high resolution and also by incorporating the full use of nondetections in the analysis.…”

Section: Introductionmentioning

confidence: 99%

The Distribution of Metallicity in the Intergalactic Medium atz ∼ 2.5: Oviand CivAbsorption in the Spectra of Seven QSOs

Simcoe

Sargent

Rauch

2004

ApJ

224

319

View full text Add to dashboard Cite

We present a direct measurement of the metallicity distribution function for the high-redshift intergalactic medium (IGM). We determine the shape of this function using survival statistics, which incorporate both detections and nondetections of O vi and C iv absorption, associated with H i lines in high-resolution quasar spectra. The O vi sample (taken from seven QSOs at z abs $ 2:5) contains lines with N H i ! 10 13:6 , encompassing $50% of all baryons at z $ 2:5. Our survey accounts for %98.8% of the C iv mass and %90% of the O vi mass in the universe at this epoch. We find a median intergalactic abundance of ½O; C=H ¼ À2:82; the differential abundance distribution is approximately lognormal with mean ½C; O=H h i% À2:85 and ¼ 0:75 dex. We discuss the sensitivity of these results to the assumed form of the ionizing UV radiation field. Some $60%-70% of lines in the Ly forest are enriched to observable levels of ½O; C=H k À3:5, while the remaining $30% of the lines have even lower abundances. Thus we have not detected a universal metallicity floor, as has been suggested for some Population III enrichment scenarios. In fact, we argue that the bulk of the intergalactic metals formed later than the first stars that are thought to have triggered reionization. We do not observe a strong trend of decreasing metallicity toward the lower density IGM, at least within regions that would be characterized as filaments in numerical simulations. However, an [O/H] enhancement may be present at somewhat high densities. We estimate that roughly half of all baryons at these redshifts have been enriched to ½O; C=H k À3:5. Using a simple ''closed box'' model for the metallicity evolution of the IGM, we estimate the chemical yield of galaxies formed prior to z $ 2:5, finding that the typical galaxy recycled 0.1%-0.4% of its mass back into the IGM as heavy elements in the first 3 Gyr after the big bang.

show abstract

“…However, in a simple picture where O vi and C iv arise from spatially distinct volumes one would expect to find O vi shifted statistically to higher as well as lower velocities. Checking the O vi selected systems reported by Carswell et al (2002) and Simcoe et al (2002), O vi features at high redshift seem to be shifted to positive velocities with respect to C iv if they are displaced at all. At low redshift Tripp et al (2008) have recently found a displacement between H i and O vi in particular for complex O vi systems.…”

Section: Comparison To C Ivmentioning

confidence: 88%

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

Fechner

Richter

2009

A&A

View full text Add to dashboard Cite

Aims. We present a study of N v absorption systems at 1.5 z 2.5 in the spectra of 19 QSOs, based on data obtained with the VLT/UVES instrument. Our analysis includes both the absorbers arising from the intergalactic medium, as well as systems in the vicinity of the background quasar. Methods. We construct detailed photoionization models to study the physical conditions and abundances in the absorbers and to constrain the spectral hardness of the ionizing radiation.Results. The rate of incidence for intervening N v components is dN/dz = 3.38 ± 0.43, corresponding to dN/dX = 1.10 ± 0.14. The column density distribution function is fitted by the slope β = 1.89 ± 0.22, consistent with measurements of C iv and O vi. The narrow line widths (b N v ∼ 6 km s −1 ) imply photoionization rather than collisions as the dominating ionization process. The column densities of C iv and N v are correlated but show different slopes for intervening and associated absorbers, which indicates different ionizing spectra. Associated systems are found to be more metal-rich, denser, and more compact than intervening absorbers. This conclusion is independent of the adopted ionizing radiation.

show abstract

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

Cited by 89 publications

References 23 publications

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

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

The Distribution of Metallicity in the Intergalactic Medium atz ∼ 2.5: Oviand CivAbsorption in the Spectra of Seven QSOs

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

Contact Info

Product

Resources

About