Constraining the temperature–density relation of the intergalactic medium with the Lyman-alpha and beta forests

Boera, Elisa and Murphy, Michael T. and Becker, George D. and Bolton, James S. (2016) Constraining the temperature–density relation of the intergalactic medium with the Lyman-alpha and beta forests. Monthly Notices of the Royal Astronomical Society, 456 (1). L79-L83. ISSN 1365-2966

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Abstract

The post-reionization thermal state of the intergalactic medium is characterized by a power-law relationship between temperature and density, with a slope determined by the parameter γ. We describe a new method to measure γ using the ratio of flux curvature in the Lyman α and β forests. At a given redshift, this curvature ratio incorporates information from the different gas densities traced by Lyman α and β absorption. It is relatively simple and fast to compute and appears robust against several observational uncertainties. We apply this technique to a sample of 27 high-resolution quasar spectra from the Very Large Telescope. While promising statistical errors on γ appear to be achievable with these spectra, to reach its full potential, the dependence of the curvature ratio on the thermal state of the gas in the foreground Lyman α forest will require further, detailed forward modelling.

Item Type: Article
Keywords: intergalactic medium, quasar: absorption lines, cosmology: observations
Schools/Departments: University of Nottingham, UK > Faculty of Science > School of Physics and Astronomy
Identification Number: 10.1093/mnrasl/slv172
Depositing User: Bolton, James
Date Deposited: 05 May 2017 11:04
Last Modified: 05 May 2017 16:38
URI: http://eprints.nottingham.ac.uk/id/eprint/42516

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