On Modeling and Measuring the Temperature of the z~5 IGM

Abstract

The temperature of the low-density intergalactic medium (IGM) at high redshift is sensitive to the timing and nature of hydrogen and HeII reionization, and can be measured from Lyman-alpha forest absorption spectra. Since the memory of intergalactic gas to heating during reionization gradually fades, measurements as close as possible to reionization are desirable. In addition, measuring the IGM temperature at sufficiently high redshifts should help to isolate the effects of hydrogen reionization since HeII reionization starts later, at lower redshift. Motivated by this, we model the IGM temperature at z>5 using semi-numeric models of patchy reionization. We construct mock Lyman-alpha forest spectra from these models and consider their observable implications. We find that the small-scale structure in the Lyman-alpha forest is sensitive to the temperature of the IGM even at redshifts where the average absorption in the forest is as high as 90%. We forecast the accuracy at which the z~5 IGM temperature can be measured using existing samples of high resolution quasar spectra, and find that interesting constraints are possible. For example, an early reionization model in which reionization ends at z~10 should be distinguishable -- at high statistical significance -- from a lower redshift model where reionization completes at z~6. We discuss improvements to our modeling that may be required to robustly interpret future measurements.

20 pages, 15 figures

References in corpus (10)

• A New Calculation of the Ionizing Background Spectrum and the Effects of HeII Reionization
• The morphology of HII regions during reionization
• HeII Reionization and its Effect on the IGM
• Studying Reionization with Ly-alpha Emitters
• Keeping the Universe ionised: Photo-heating and the clumping factor of the high-redshift intergalactic medium
• A Direct Precision Measurement of the Intergalactic Lyman-alpha Opacity at 2<z<4.2
• Imprint of Inhomogeneous Hydrogen Reionization on the Temperature Distribution of the Intergalactic Medium
• Quasar Proximity Zones and Patchy Reionization
• The End of Helium Reionization at z~2.7 Inferred from Cosmic Variance in HST/COS HeII Lyman Alpha Absorption Spectra
• Probing the Epoch of Reionization with the Lyman Alpha Forest at z~4-5

Cited by in corpus (11)

• The Sherwood-Relics simulations: overview and impact of patchy reionization and pressure smoothing on the intergalactic medium
• Small-scale structure and the Lyman-$\alpha$ forest baryon acoustic oscillation feature
• Thermal Instabilities and Shattering in the High-Redshift WHIM: Convergence Criteria and Implications for Low-Metallicity Strong HI Absorbers
• How to Search for Islands of Neutral Hydrogen in the $z\sim 5.5$ IGM
• The effect of inhomogeneous reionisation on the Lyman-$\alpha$ forest power spectrum at redshift $z>4$: implications for thermal parameter recovery
• Constraints on Dark Matter-Baryon Scattering from the Temperature Evolution of the Intergalactic Medium
• Impact of inhomogeneous reionization on the Lyman-α forest
• Constraining reionization with the first measurement of the cross-correlation between the CMB optical-depth fluctuations and the Compton y-map
• The impact of temperature fluctuations on the large-scale clustering of the Ly$\alpha$ forest
• Improving IGM temperature constraints using wavelet analysis on high-redshift quasars
• The Lyman-beta forest as a cosmic thermometer