Evidence for structure in the H I column density distribution of QSO absorbers

Petitjean, P.; Webb, John R.; Rauch, Michael; Carswell, R. F.; Lanzetta, Kenneth M.

doi:10.1093/mnras/262.2.499

Cited by 180 publications

(229 citation statements)

References 0 publications

Supporting

Mentioning

207

Contrasting

Order By: Relevance

“…Our results are in good agreement with the Petitjean et al (1993) data over the whole column density range down to log N H i ∼ 13.5, following a power law at log N H i = [12. 75,14].…”

Section: Figsupporting

confidence: 88%

“…We compare our results with the observations by Petitjean et al (1993) and Hu et al (1995). Our results are in good agreement with the Petitjean et al (1993) data over the whole column density range down to log N H i ∼ 13.5, following a power law at log N H i = [12.…”

Section: Figsupporting

confidence: 85%

“…The grey data points mark the column densities that are affected by incompleteness. The stars are the data points obtained by Petitjean et al (1993). The filled circles at log N H i > 20.1 and at 19 < log N H i < 20.1 are from the SDSS II DR7 at z = 3.02 by Noterdaeme et al (2009) dependent on the N H i column density range (Prochaska et al 2010;Altay et al 2011).…”

Section: Figmentioning

confidence: 99%

See 2 more Smart Citations

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

Self Cite

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

“…Our results are in good agreement with the Petitjean et al (1993) data over the whole column density range down to log N H i ∼ 13.5, following a power law at log N H i = [12. 75,14].…”

Section: Figsupporting

confidence: 88%

Section: Figsupporting

confidence: 85%

Section: Figmentioning

confidence: 99%

See 1 more Smart Citation

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

Self Cite

104

View full text Add to dashboard Cite

show abstract

“…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%

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

View full text Add to dashboard Cite

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.

show abstract

“…Although the technique adopted by T02 and S04 was similar, i.e. a statistical correction for the unidentified absorbers by considering an empirical parametrisation (see Petitjean et al 1993;Davé & Tripp 2001), the overall correction applied was very different as pointed out by S04. In fact, S04 noted that the correction considered by T02 was less than 1% over the whole rest-frame wavelength range, which underestimated the number of Ly α absorbers by a factor of ∼ 50 at z = 0.1.…”

Section: Introductionmentioning

confidence: 99%

The first ultraviolet quasar-stacked spectrum at z ≃ 2.4 from WFC3

Lusso

Worseck

Hennawi

et al. 2015

Monthly Notices of the Royal Astronomical Society

273

355

View full text Add to dashboard Cite

The ionising continuum from active galactic nuclei (AGN) is fundamental for interpreting their broad emission lines and understanding their impact on the surrounding gas. Furthermore, it provides hints on how matter accretes onto supermassive black holes. Using HST's Wide Field Camera 3 we have constructed the first stacked ultraviolet (rest-frame wavelengths 600-2500Å) spectrum of 53 luminous quasars at z 2.4, with a state-of-the-art correction for the intervening Lyman forest and Lyman continuum absorption. The continuum slope (f ν ∝ ν αν ) of the full sample shows a break at ∼912Å with spectral index α ν = −0.61 ± 0.01 at λ > 912Å and a softening at shorter wavelengths (α ν = −1.70 ± 0.61 at λ 912Å). Our analysis proves that a proper intergalactic medium absorption correction is required to establish the intrinsic continuum emission of quasars. We interpret our average ultraviolet spectrum in the context of photoionisation, accretion disk models, and quasar contribution to the ultraviolet background. We find that observed broad line ratios are consistent with those predicted assuming an ionising slope of α ion =−2.0, similar to the observed ionising spectrum in the same wavelength range. The continuum break and softening are consistent with accretion disk plus X-ray corona models when black hole spin is taken into account. Our spectral energy distribution yields a 30% increase to previous estimates of the specific quasar emissivity, such that quasars may contribute significantly to the total specific Lyman limit emissivity estimated from the Lyα forest at z < 3.2.

show abstract

Evidence for structure in the H I column density distribution of QSO absorbers

Cited by 180 publications

References 0 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

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

The first ultraviolet quasar-stacked spectrum at z ≃ 2.4 from WFC3

Contact Info

Product

Resources

About