Constraining the temperature–density relation of the intergalactic medium with the Lyman α and β forests

Boera, Elisa; Murphy, Michael T.; Becker, George D.; Bolton, James S.

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.

Citation

Boera, E., Murphy, M. T., Becker, G. D., & Bolton, J. S. (2016). Constraining the temperature–density relation of the intergalactic medium with the Lyman α and β forests. Monthly Notices of the Royal Astronomical Society, 456(1), L79-L83. https://doi.org/10.1093/mnrasl/slv172

• Journal Article Type: Article
• Acceptance Date: Oct 28, 2015
• Online Publication Date: Dec 10, 2015
• Publication Date: Feb 11, 2016
• Deposit Date: May 5, 2017
• Publicly Available Date: May 5, 2017
• Journal: Monthly Notices of the Royal Astronomical Society
• Print ISSN: 0035-8711
• Electronic ISSN: 1365-2966
• Publisher: Oxford University Press
• Peer Reviewed: Peer Reviewed
• Volume: 456
• Issue: 1
• Pages: L79-L83
• DOI: https://doi.org/10.1093/mnrasl/slv172
• Keywords: intergalactic medium, quasar: absorption lines, cosmology: observations
• Public URL: https://nottingham-repository.worktribe.com/output/776495
• Publisher URL: https://academic.oup.com/mnrasl/article-lookup/doi/10.1093/mnrasl/slv172
• Contract Date: May 5, 2017