The Lyman alpha forest opacity and the metagalactic hydrogen ionization rate at z~ 2-4

By J. Bolton, M. Haehnelt, M. Viel, Volker Springel. 2004

171 citations recorded by the source corpus.

Estimates of the metagalactic hydrogen ionization rate from the Lya forest opacity in QSO absorption spectra depend on the complex density distribution of neutral hydrogen along the line of sight. We use a large suite of high-resolution hydrodynamical simulations to investigate in detail the dependence of such estimates on physical and numerical parameters in the context of ACDM models. Adopting fiducial values for cosmological parameters together with published values of the temperature of the IGM and the effective optical depth, the metagalactic ionization rates that reproduce the Lya effective optical depth at z = [2, 3, 4] are Γ HI = [1.3± 0.8 0.5 , 0.9 ± 0.3, 1.0± 0.5 0.3 ] × 10 -12 s -1 , respectively. The errors include estimates of uncertainties in the relevant physical parameters and the numerical accuracy of the simulations. We find the errors are dominated by the uncertainty in the temperature of the low-density IGM. The estimated metagalactic hydrogen ionization rate for the neutral hydrogen distribution in the current concordance ACDM model is more than four times the value inferred for that in an Einstein-de Sitter model of the same rms-density-fluctuation amplitude σ 8 . The estimated ionization rate is also more than double that expected from updated estimates of the emissivity of observed QSOs alone. A substantial contribution from galaxies appears to be required at all redshifts.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

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Citations in the corpus

He ii REIONIZATION AND ITS EFFECT ON THE INTERGALACTIC MEDIUM (2008, methodology): “Bolton et al. (2005), Becker et al. (2007), and especially Faucher-Giguère et al. (2008b) measured the hydrogen photoionization rate (ΓHI) to be flat as a function of redshift using the flux decrement method on 2 < z < 4 HI Lyα forest data and to within a factor of ∼ 2 given by ΓHI(z) = 10 −12 s−1.”
Faint AGNs at z > 4 in the CANDELS GOODS-S field: looking for contributors to the reionization of the Universe (2015, methodology): “Some values depend on the UV background adopted in numerical simulations to reproduce the mean flux decrement observed in the Lyman-α forest of QSO spectra (Faucher-Giguere et al. (2008), Bolton et al. (2005), Becker & Bolton (2013), Fan et al. (2006), Wyithe & Bolton (2011)).”
The physics of the intergalactic medium (2007, methodology): “43 Results from Meiksin and White (2004), Bolton et al. (2005) and Bolton and Haehnelt (2007) are shown in Table V.”
Evidence of patchy hydrogen reionization from an extreme Lyα trough below redshift six (2014, background): “6 stands in stark contrast to its nearly constant value over 2 < z < 5 (e.g., Bolton et al. 2005; Faucher-Giguère et al. 2008; Becker & Bolton 2013).”
A DEEP HUBBLE SPACE TELESCOPE SEARCH FOR ESCAPING LYMAN CONTINUUM FLUX AT z ∼ 1.3: EVIDENCE FOR AN EVOLVING IONIZING EMISSIVITY (2010, background): “Recent investigations of the ionizing background at high redshift (Bolton et al. 2005; Becker et al. 2007) note that the Hi–photoionization rate is fairly flat between 2 < z < 4, which implies an increase in the ionizing emissitivity at higher redshifts (Faucher-Giguère et al. 2008).”
The Direct Detection of Lyman Continuum Emission from Star-forming Galaxies at z~3 (2006, background): “…for the contribution from LBGs to the ionizing background does not exceed the Lyα forest-inferred result, and, furthermore, the new sum of the contributions from galaxies and QSOs (Hunt et al. 2004) is roughly consistent with the total H I ionizing radiation field presented in Bolton et al. (2005).”
A refined measurement of the mean transmitted flux in the Lyα forest over 2 < z < 5 using composite quasar spectra (2012, background): “The mean flux, which is often expressed in terms of an effective optical depth, τeff(z) = − lnF (z), directly constrains, for example, the intensity of the metagalactic ionizing background (e.g., Rauch et al. 1997; McDonald & Miralda-Escudé 2001; Bolton et al. 2005).”
An Observational Determination of the Bolometric Quasar Luminosity Function (2006, methodology): “We compare with several observational estimates of the total 12 from Scott et al. (2000), McDonald & Miralda-Escudé (2001, 2003), Tytler et al. (2004), Bolton et al. (2005), Rollinde et al. (2005), and Fan et al. (2006b) using various methods (for a review see Fan et al. 2006a).”
Measurements of the UV background at 4.6 < z < 6.4 using the quasar proximity effect (2010, methodology): “The UVB in the simulation is adjusted until the mean flux in artificial Lyα forest spectra is equal to that in the real data (see e.g., Rauch et al. 1997; Songaila et al. 1999; Tytler et al. 2004; Bolton et al. 2005; Kirkman et al. 2005; Jena et al. 2005).”
DIFFUSE Lyα EMITTING HALOS: A GENERIC PROPERTY OF HIGH-REDSHIFT STAR-FORMING GALAXIES (2011, background): “The radiation field intensity is usually expressed as Jν ≃ 2 − 10 × 10 −22 ergs s−1 cm−2 Hz−1 sr−1, where the quoted range indicates the dispersion among published observational or theoretical estimates (e.g., Shapley et al. 2006; Bolton et al. 2005; Scott et al. 2000; Faucher-Giguère et al. 2008).”
Population III stars: hidden or disappeared? (2007, background): “…and heating rates are calculated at equilibrium with a background ionizing radiation due to the combined contribution of galaxies and quasars, taken from Haardt & Madau (1996), shifted so that the intensity at 1 Ryd is Jν = 0.3 × 10 −21 erg s−1 Hz−1, in agreement with Bolton et al. (2005).”
New Measurements of the Ionizing Ultraviolet Background over 2 < z < 5 and Implications for Hydrogen Reionization (2013, methodology): “As discussed in Bolton et al. (2005) and Bolton & Haehnelt (2007), however, the calibration of H i ionization rate as a function of Lyα opacity will depend on cosmology.”
Cosmic dynamics in the era of Extremely Large Telescopes (2008, unknown): “7 of Bolton et al. (2005): d /dz = −0.3 .”
The Evolution of the Intergalactic Medium (2015, methodology): “A byproduct of this adjustment is a “flux decrement” measurement of Γ, with Becker & Bolton (2013) finding a remarkably constant Γ ≈ 10−12±0.3 s−1 over 2 < z < 5 (see also Rauch et al. 1997; Meiksin & White 2003; Bolton et al. 2005; Faucher-Giguère et al. 2008a).”
Reionization and Cosmology with 21-cm Fluctuations (2009, background): “The ionization fraction in the low density regime is controlled by the balance between the ionization rate owing to the UV background and the recombination rate at the local gas density (e.g. Bolton et al. 2005).”
An improved measurement of the flux distribution of the Lyα forest in QSO absorption spectra: the effect of continuum fitting, metal contamination and noise properties (2007, background): “…effective optical depth is the quantity which directly goes into measurements of the amplitude of the metagalactic UV background (Rauch et al. 1997; Bolton et al. 2005) and plays a crucial role in calibrating measurements of the matter power spectrum from Lyα forest data based on the flux power…”
Escape of Ionizing Radiation from High-Redshift Galaxies (2007, background): “The ionizing radiation from galaxies is thought to be responsible for the re-ionization of the universe (e.g., Madau et al. 1999; Bolton et al. 2005), altering the thermal state of the IGM (Gnedin & Hui 1998; Gnedin 2000; Ricotti et al. 2000; Schaye et al. 2000; McDonald et al. 2001; Fechner &…”
GeV gamma-ray attenuation and the high-redshift UV background (2009, methodology): “…one searches for the decrease in Lyα emissions near an AGN (Dall’Aglio, Wisotzki & Worseck 2008; Liske & Williger 2001), and flux decrement analysis, which utilizes hydrodynamic simulations to model the distribution of Lyα absorption along the line of sight to an AGN (e.g. Bolton et al. 2005).”
Evolution of the Intergalactic Opacity: Implications for the Ionizing Background, Cosmic Star Formation, and Quasar Activity (2008, background): “Bolton et al. (2005), in particular, inferred Γ from the Lyα opacity measurement of Schaye et al. (2003) and also found its evolution to be consistent with being constant at 2 ≤ z ≤ 4.”
New insights into the stellar content and physical conditions of star-forming galaxies at z = 2-3 from spectral modelling (2008, background): “Nevertheless, there have been claims that fesc does evolve in the sense that it was higher at earlier times (Inoue, Iwata & Deharveng 2006 – see also Bolton et al. 2005 for less direct arguments), and therefore this could also be an important factor contributing to the offset of the high-z galaxies…”