Probing reionization using quasar near-zones at redshift z ~ 6

Abstract

Using hydrodynamical simulations coupled to a radiative transfer code, we study the additional heating effects in the intergalactic medium (IGM) produced by $z\sim 6$ quasars in their near-zones. If helium is predominantly in HeII to begin with, both normalization ($T_0$) and slope ($\gamma$) of the IGM effective equation-of-state get modified by the excess ionization from the quasars. Using the available constraints on $T_0$ at $z\sim 6$, we discuss implications for the nature and epoch of HI and HeII reionization. We study the extent of the HeIII region as a function of quasar age and show, for a typical inferred age of $z\sim 6$ quasars (i.e. $\sim 10^8$ yrs), it extends up to 80% of the HI proximity region. For these long lifetimes, the heating effects can be detected even when all the HI lines from the proximity region are used. Using the flux and curvature probability distribution functions (PDFs), we study the statistical detectability of heating effects as a function of initial physical conditions in the IGM. For the present sample size, cosmic variance dominates the flux PDF. The curvature statistics is more suited to capturing the heating effects beyond the cosmic variance, even if the sample size is half of what is presently available.

20 pages, 15 figures, 3 tables; version accepted for publication in MNRAS

References in corpus (15)

• A luminous quasar at a redshift of z = 7.085
• Cosmology at Low Frequencies: The 21 cm Transition and the High-Redshift Universe
• Observational constraints on Cosmic Reionization
• The End of the Reionization Epoch Probed by Ly-alpha Emitters at z=6.5 in the Subaru Deep Field
• The observed ionization rate of the intergalactic medium and the ionizing emissivity at z >5: Evidence for a photon starved and extended epoch of reionization
• Four quasars above redshift 6 discovered by the Canada-France High-z Quasar Survey
• Population III stars: hidden or disappeared ?
• Evolution of the Intergalactic Opacity: Implications for the Ionizing Background, Cosmic Star Formation, and Quasar Activity
• The nature and evolution of the highly ionized near-zones in the absorption spectra of z~6 quasars
• The End of Helium Reionization at z~2.7 Inferred from Cosmic Variance in HST/COS HeII Lyman Alpha Absorption Spectra
• Significant primordial star formation at redshifts z ~ 3-4
• The Lyman-alpha forest and WMAP year three
• Updating reionization scenarios after recent data
• Inhomogeneous Helium Reionization and the Equation of State of the Intergalactic Medium
• Fluctuations in the Ionizing Background During and After Helium Reionization

Cited by in corpus (11)

• New synthesis models of consistent extragalactic background light over cosmic time
• Reionization and high-redshift galaxies: the view from quasar absorption lines
• The redshift evolution of escape fraction of hydrogen ionizing photons from galaxies
• A consistent and robust measurement of the thermal state of the IGM at $2\le z\le 4$ from a large sample of Ly$\alpha$ forest spectra: Evidence for late and rapid HeII reionization
• Cosmic reionization after Planck II: contribution from quasars
• A Short Introduction to Reionization Physics
• First study of reionization in the Planck 2015 normalized closed $\Lambda$CDM inflation model
• Probing the thermal history during reionization using a semi-numerical photon-conserving code SCRIPT
• Efficient adiabatic hydrodynamical simulations of the high-redshift intergalactic medium
• Measuring the equation of state of the high-z intergalactic medium using curvature statistics
• Recovering Density Fields inside Quasar Proximity Zones at $z\sim 6$