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Towards a unified description of the intergalactic medium at redshift z ≈ 2.5

Prochaska, J.X.; Madau, P.; O'Meara, J.M.; Fumagalli, M.

Towards a unified description of the intergalactic medium at redshift z ≈ 2.5 Thumbnail


Authors

J.X. Prochaska

P. Madau

J.M. O'Meara



Abstract

We examine recent measurements of the z ≈ 2.5 intergalactic medium (IGM) which constrain the H I frequency distribution f(NHI) and the mean free path λ912mfp to ionizing radiation. We argue that line-blending and the clustering of strong absorption-line systems have led previous authors to systematically overestimate the effective Lyman limit opacity, yielding too small of a λ912mfp for the IGM. We further show that recently published measurements of f(NHI) at NHI≈1016cm−2 lie in strong disagreement, implying underestimated uncertainty from sample variance and/or systematics like line-saturation. Allowing for a larger uncertainty in the f(NHI) measurements, we provide a new cubic Hermite spline model for f(NHI) which reasonably satisfies all of the observational constraints under the assumption of randomly distributed absorption systems. We caution, however, that this formalism is invalid in the light of absorber clustering and use a toy model to estimate the effects. Future work must properly account for the non-Poissonian nature of the IGM.

Citation

Prochaska, J., Madau, P., O'Meara, J., & Fumagalli, M. (2014). Towards a unified description of the intergalactic medium at redshift z ≈ 2.5. Monthly Notices of the Royal Astronomical Society, 438(1), 476-486. https://doi.org/10.1093/mnras/stt2218

Journal Article Type Article
Publication Date Feb 11, 2014
Deposit Date Apr 6, 2014
Publicly Available Date Jun 20, 2014
Journal Monthly Notices of the Royal Astronomical Society
Print ISSN 0035-8711
Electronic ISSN 1365-2966
Publisher Royal Astronomical Society
Peer Reviewed Peer Reviewed
Volume 438
Issue 1
Pages 476-486
DOI https://doi.org/10.1093/mnras/stt2218
Keywords Intergalactic medium.

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Copyright Statement
This article has been accepted for publication in Monthly notices of the Royal Astronomical Society © 2013 The Authors Published by Oxford University Press on behalf of Royal Astronomical Society. All rights reserved.







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