SIMBAD references

2019ApJ...883..163B - Astrophys. J., 883, 163-163 (2019/October-1)

The evolution of O I over 3.2 < z < 6.5: reionization of the circumgalactic medium.

BECKER G.D., PETTINI M., RAFELSKI M., D'ODORICO V., BOERA E., CHRISTENSEN L., CUPANI G., ELLISON S.L., FARINA E.P., FUMAGALLI M., LOPEZ S., NEELEMAN M., RYAN-WEBER E.V. and WORSECK G.

Abstract (from CDS):

We present a survey for metal absorption systems traced by neutral oxygen over 3.2 < z < 6.5. Our survey uses Keck/ESI and VLT/X-Shooter spectra of 199 QSOs with redshifts up to 6.6. In total, we detect 74 O I absorbers, of which 57 are separated from the background QSO by more than 5000 km s–1. We use a maximum likelihood approach to fit the distribution of O I λ1302 equivalent widths in bins of redshift and from this determine the evolution in number density of absorbers with W1302 > 0.05 Å, of which there are 49 nonproximate systems in our sample. We find that the number density does not monotonically increase with decreasing redshift, as would naively be expected from the buildup of metal-enriched circumgalactic gas with time. The number density over 4.9 < z < 5.7 is a factor of 1.7-4.1 lower (68% confidence) than that over 5.7 < z < 6.5, with a lower value at z < 5.7 favored with 99% confidence. This decrease suggests that the fraction of metals in a low-ionization phase is larger at z ∼ 6 than at lower redshifts. Absorption from highly ionized metals traced by C IV is also weaker in higher-redshift O I systems, supporting this picture. The evolution of O I absorbers implies that metal-enriched circumgalactic gas at z ∼ 6 is undergoing an ionization transition driven by a strengthening ultraviolet background. This in turn suggests that the reionization of the diffuse intergalactic medium may still be ongoing at or only recently ended by this epoch.

Abstract Copyright: © 2019. The American Astronomical Society. All rights reserved.

Journal keyword(s): Intergalactic medium - Quasar absorption line spectroscopy - Circumgalactic medium - Reionization - High-redshift galaxies

VizieR on-line data: <Available at CDS (J/ApJ/883/163): table1.dat table2.dat>

Simbad objects: 199

goto Full paper

goto View the references in ADS

To bookmark this query, right click on this link: simbad:2019ApJ...883..163B and select 'bookmark this link' or equivalent in the popup menu


2023.01.30-23:02:58

© Université de Strasbourg/CNRS

    • Contact