Helium reionization and the thermal proximity effect

Abstract

We examine the temperature structure of the intergalactic medium IGM) surounding a hard radiation source, such as a Quasi-Stellar Object (QSO), as it responds to the onset of helium reionization by the source. We model the reionization using a radiative transfer (RT) code coupled to a particle-mesh (PM) N-body code. Neutral hydrogen and helium are initially ionized by a starburst spectrum, which is allowed to gradually evolve into a power law spectrum (fnu ~ nu^(-0.5)). Multiple simulations were performed with different times for the onset and dominance of the hard spectrum, with onset redshifts ranging from z = 3.5 to 5.5. The source is placed in a high-density region to mimic the expected local environment of a QSO. Simulations with the source placed in a low-density environment were also performed as control cases to explore the role of the environment on the properties of the surrounding IGM. We find in both cases that the IGM temperature within the HeIII region produced exceeds the IGM temperature before full helium reionization, resulting in a "thermal proximity effect", but that the temperature in the HeIII region increases systematically with distance from the source. With time the temperature relaxes with a reduced spread as a function of impact parameter along neighbouring lines of sight, although the trend continues to persist until z = 2. Such a trend could be detected using the widths of intervening metal absorption systems using high resolution, high signal-to-noise ratio spectra.

17 pages, 12 figures, for publication in MNRAS

References in corpus (44)

• First Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Determination of Cosmological Parameters
• Five-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Likelihoods and Parameters from the WMAP data
• Evidence for Reionization at z ~ 6: Detection of a Gunn-Peterson Trough in a z=6.28 Quasar
• Equation of State of the Photoionized Intergalactic Medium
• Radiative Transfer in a Clumpy Universe: III. The Nature of Cosmological Ionizing Sources
• The Rest-Frame Extreme Ultraviolet Spectral Properties of QSOs
• Evolution of the Ionizing Background and the Epoch of Reionization from the Spectra of z~6 Quasars
• Probing the Universe with the Lyman-alpha Forest: I. Hydrodynamics of the Low Density IGM
• The thermal history of the intergalactic medium
• Clustering of High Redshift ($z\ge 2.9$) Quasars from the Sloan Digital Sky Survey
• P3M-SPH simulations of the Lyman-alpha Forest
• Early reionization by miniquasars
• HeII Reionization and its Effect on the IGM
• Baryonic Signatures in Large-Scale Structure
• Evolution of the Intergalactic Opacity: Implications for the Ionizing Background, Cosmic Star Formation, and Quasar Activity
• The Evolution of the Effective Equation of State of the IGM
• A Composite Extreme Ultraviolet QSO Spectrum from the Far Ultraviolet Spectroscopic Explorer
• The Lyman-alpha forest opacity and the metagalactic hydrogen ionization rate at z~2-4
• Photon Conserving Radiative Transfer around Point Sources in multi-dimensional Numerical Cosmology
• Resolving the Structure of Ionized Helium in the Intergalactic Medium with the Far Ultraviolet Spectroscopic Explorer
• Physical Properties of the Lyman Alpha Forest in a Cold Dark Matter Cosmology
• A Study of the Reionization History of Intergalactic Helium with FUSE and VLT
• Measuring the Sources of the Intergalactic Ionizing Flux
• Voigt-Profile Analysis of the Lyman-alpha Forest in a Cold Dark Matter Universe
• The effects of UV background correlations on LyA forest flux statistics
• Metallicity of the intergalactic medium using pixel statistics: IV. Oxygen
• Resolving the Lyman-alpha Forest
• Cosmological parameters sigma_8, the baryon density, and the UV background intensity from a calibrated measurement of H I Lyman-alpha absorption at z = 1.9
• Constraints on the ionization sources of the high redshift intergalactic medium
• Updating reionization scenarios after recent data
• Temperature fluctuations in the intergalactic medium
• Temperature and Kinematics of CIV Absorption Systems
• Constraints on the correlation between QSO luminosity and host halo mass from high-redshift quasar clustering
• The UV spectrum of HS1700+6416 II. FUSE observations of the HeII Lyman alpha forest
• Reionisation scenarios and the temperature of the IGM
• Photo-heating and the fate of hard photons during the reionisation of HeII by quasars
• Radiative transfer through the Intergalactic Medium
• Particle-Mesh Simulations of the Lyman-Alpha Forest
• Hydrodynamical simulations of the Lyman-Alpha forest: data comparisons
• Intergalactic HeII absorption towards QSO 1157+3143
• Searching for fluctuations in the IGM temperature using the Lyman alpha forest
• The Structure and Evolution of Lyman-alpha Forest Clouds in the Minihalo Model
• Obscured Activity: AGN, Quasars, Starbursts and ULIGs observed by the Infrared Space Observatory
• The Flux Auto- and Cross-Correlation of the Lyman-alpha Forest. I. Spectroscopy of QSO Pairs with Arcminute Separations and Similar Redshifts

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• Improved measurements of the intergalactic medium temperature around quasars: possible evidence for the initial stages of He-II reionisation at z~6
• The thermal history of the intergalactic medium down to redshift z=1.5: a new curvature measurement
• Accretion onto black holes formed by direct collapse
• A first direct measurement of the intergalactic medium temperature around a quasar at z=6
• The Role of Galaxies and AGN in Reionising the IGM - I: Keck Spectroscopy of 5 < z < 7 Galaxies in the QSO Field J1148+5251
• Time-dependent behaviour of quasar proximity zones at $z\sim 6$
• Detecting and Characterizing Young Quasars II: Four Quasars at $z\sim 6$ with Lifetimes $<10^4$ years
• Helium Reionization Simulations. II. Signatures of Quasar Activity on the IGM
• He II Proximity Effect and the Lifetime of Quasars
• Evidence for Short $\sim 1$ Myr Lifetimes from the He II Proximity Zones of $z\sim 4$ Quasars
• The impact of helium reionization on the structure of the intergalactic medium
• HST/COS Observations of Thirteen New He II Quasars
• Modeling the HeII Transverse Proximity Effect: Constraints on Quasar Lifetime and Obscuration
• Mapping quasar light echoes in 3D with Lyα forest tomography
• The Thermal Proximity Effect: A New Probe of He II Reionization History and the Quasar Lifetime
• He II Lyβ Gunn-Peterson Absorption: New HST Observations, and Theoretical Expectations
• Cosmological radiative transfer for the line-of-sight proximity effect
• Reconstructing patchy helium reionization using the cosmic microwave background and large-scale structure
• High-redshift AGN population in radiation-hydrodynamics simulations
• The effect of helium reionization on the Lyman-alpha forest hydrogen flux statistics