IGM constraints from the SDSS-III/BOSS DR9 Lyα forest transmission probability distribution function

Lee, K.-G. and Hennawi, J.P. and Spergel, D.N. and Weinberg, D.H. and Hogg, D.W. and Viel, Matteo and Bolton, James S. and Bailey, S. and Pieri, M.M. and Carithers, W. and Schlegel, D.J. and Lundgren, B. and Palanque-Delabrouille, N. and Suzuki, N. and Schneider, D.P. and Yeche, C. (2015) IGM constraints from the SDSS-III/BOSS DR9 Lyα forest transmission probability distribution function. Astrophysical Journal, 799 (2). 196/1-196/32. ISSN 1538-4357

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The Lyα forest transmission probability distribution function (PDF) is an established probe of the intergalactic medium (IGM) astrophysics, especially the temperature-density relationship of the IGM. We measure the transmission PDF from 3393 Baryon Oscillations Spectroscopic Survey (BOSS) quasars from Sloan Digital Sky Survey Data Release 9, and compare with mock spectra that include careful modeling of the noise, continuum, and astrophysical uncertainties. The BOSS transmission PDFs, measured at langzrang = [2.3, 2.6, 3.0], are compared with PDFs created from mock spectra drawn from a suite of hydrodynamical simulations that sample the IGM temperature-density relationship, γ, and temperature at mean density, T 0, where T(Δ) = T 0Δγ – 1. We find that a significant population of partial Lyman-limit systems (LLSs) with a column-density distribution slope of βpLLS ~ – 2 are required to explain the data at the low-transmission end of transmission PDF, while uncertainties in the mean Lyα forest transmission affect the high-transmission end. After modeling the LLSs and marginalizing over mean transmission uncertainties, we find that γ = 1.6 best describes the data over our entire redshift range, although constraints on T 0 are affected by systematic uncertainties. Within our model framework, isothermal or inverted temperature-density relationships (γ ≤ 1) are disfavored at a significance of over 4σ, although this could be somewhat weakened by cosmological and astrophysical uncertainties that we did not model.

Item Type: Article
Additional Information: C 2015. The American Astronomical Society. All rights reserved.
Keywords: intergalactic medium; large-scale structure of universe; methods: data analysis; quasars: absorption lines; quasars: emission lines; techniques: spectroscopic
Schools/Departments: University of Nottingham, UK > Faculty of Science > School of Physics and Astronomy
Identification Number: 10.1088/0004-637X/799/2/196
Depositing User: Bolton, James
Date Deposited: 04 May 2017 14:16
Last Modified: 06 May 2017 22:34
URI: http://eprints.nottingham.ac.uk/id/eprint/42509

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