The Evolution of the Intergalactic Medium Transmission to Redshift 6

By A. Songaila. 2004

170 citations recorded by the source corpus.

We have measured the transmission of the Lyα forest produced by neutral hydrogen scattering in the intergalactic medium between redshifts 2 and 6.3 using high signal-to-noise, high-resolution (R ≥ 5000) observations of 50 quasars spread over the redshift range. We use a uniform set of 15 Å intervals covering Lyα, Lyβ, and Lyγ absorption regions to tabulate the forest transmission as a function of redshift. The transmitted fractions show a relatively smooth evolution over the entire range of redshifts, which can be modeled with a smoothly decreasing ionization rate. Previous claims of an abrupt change at z ∼ 6 appear in part to be a consequence of an incorrect conversion of Lyβ to Lyα optical depths. The tabulated transmissions can be used to calculate the colors of objects with a specified input spectrum as a function of redshift. We calculate the colors of a flat-fν galaxy with a large intrinsic continuum break as an important example.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/63ad8e647a56775ac2ea7c128234687e76204cb7

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Citations in the corpus

Four Quasars above Redshift 6 Discovered by the Canada-France High-z Quasar Survey (2007, background): “We note, as emphasized by Songaila (2004), that if flux is detected at all at Lyα, it is better to adopt this measurement than to trust the apparently higher S/N Lyβ measurement because of uncertainty in the foreground subtraction.”
A strong redshift dependence of the broad absorption line quasar fraction (2010, methodology): “The model results in an excellent match to the observed median ugr colours of the SDSS quasars over the redshift range 1.7 z 5.0, representing a significant improvement over the parametrization based on the results of Songaila (2004) that was employed previously.”
A Survey of z > 5.7 Quasars in the Sloan Digital Sky Survey. IV. Discovery of Seven Additional Quasars (2004, methodology): “The effective Lyα optical depth in this dark gap is τeff > 5.5, comparable to the limits measured in the complete Gunn-Peterson (1965) troughs detected in quasars at z > 6.1 (Becker et al. 2001, Fan et al. 2002, White et al. 2003, Paper III, see also Songaila 2004).”
Observational Constraints on Cosmic Reionization (2006, background): “J., 600: 570-579 Sokasian et al. 2002Sokasian, A., Abel, T., Hernquist, L. 2002, MNRAS, 332, 601 Songaila 2004Songaila, A. 2004, A.J., 127: 2598-2603 Songaila 2005Songaila, A. 2005, A.J., in press (astro-ph/0507649) Songaila & Cowie 2002Songaila, A., & Cowie, L. L. 2002, A.J., 123: 2183-2196…”
Constraining the Evolution of the Ionizing Background and the Epoch of Reionization with z ∼ 6 Quasars. II. A Sample of 19 Quasars (2005, methodology): “At zabs 4.9, we plot the data from Songaila (2004), where 95% variation due to sample variance is shown for each redshift.”
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 (2007, methodology): “…beyond the putative tail end of the hydrogen reionization epoch at z 6, determining the ionization state of the IGM is still problematic (e.g. Fan et al. 2002; Santos 2004; Songaila 2004; Gallerani, Choudhury & Ferrara 2006; Fan et al. 2006; Bolton & Haehnelt 2007; Dijkstra, Wyithe & Haiman 2007).”
THE z = 5 QUASAR LUMINOSITY FUNCTION FROM SDSS STRIPE 82 (2012, unknown): “We also force continuity between the column density distribution function (dn/dNHIdz) at low and high column densities, and check the derived effective optical depth (τeff) against the measurements of Songaila (2004) and Fan et al. (2006a).”
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): “…depth and the flux PDF due to H i absorption have either removed the metal lines statistically (Tytler et al. 2004; Kirkman et al. 2005), excluded the metal-contaminated regions from the study (McDonald et al. 2000; Lidz et al. 2006) or included absorption due to metal lines (Songaila 2004).”
SPECTROSCOPIC OBSERVATIONS OF LYMAN BREAK GALAXIES AT REDSHIFTS ∼4, 5, AND 6 IN THE GOODS-SOUTH FIELD (2009, unknown): “Consistent with quasar results (e.g., Songaila 2004), the IGM transparency is estimated to be of the order of 1%.”
The Growth of H II Regions During Reionization (2004, background): “Observations of Lyα absorption in the spectra of high-redshift quasars indicate that reionization ends at z ∼ 6.5 (Becker et al. 2001; Fan et al. 2002; White et al. 2003; Wyithe & Loeb 2004), although this interpretation is controversial (Songaila 2004).”
A refined measurement of the mean transmitted flux in the Lyα forest over 2 < z < 5 using composite quasar spectra (2012, methodology): “At the highest redshifts (z > 5), F (z) measurements have generally relied on extrapolating a power-law continuum from redward of the Lyα emission line (Songaila 2004; Fan et al. 2006; Becker et al. 2007).”
The UKIRT Infrared Deep Sky Survey ZY JHK photometric system: passbands and synthetic colours (2006, methodology): “Absorption due to Lyman-α, β and γ transitions in the Lyman-α forest are included using data from Songaila (2004), which extends to a redshift of z = 6.5.”
Evidence of patchy hydrogen reionization from an extreme Lyα trough below redshift six (2014, background): “Similar data at these redshifts were obtained by Songaila (2004).”
A Direct Precision Measurement of the Intergalactic Lyα Opacity at 2 ≤ z ≤ 4.2 (2007, background): “…spectra (Press et al. 1993; Rauch et al. 1997; Songaila et al. 1999; McDonald & Miralda-Escudé 2001; Meiksin & White 2003; Tytler et al. 2004a; Songaila 2004; Bolton et al. 2005; Kirkman et al. 2005; Jena et al. 2005; Fan et al. 2006b; Becker et al. 2007; Bolton & Haehnelt 2007), as well as…”
SUBARU HIGH-z EXPLORATION OF LOW-LUMINOSITY QUASARS (SHELLQs). I. DISCOVERY OF 15 QUASARS AND BRIGHT GALAXIES AT 5.7 < z < 6.9 (2016, unknown): “The IGM H I opacity data are taken from Songaila (2004).”
Statistical Probes of Reionization with 21 Centimeter Tomography (2004, background): “Unfortunately, the optical depth of a fully neutral medium is so high that current measurements only require a mean neutral fraction x̄H & 10−3, and even this limit has been disputed (Songaila 2004).”
Taxing the rich: Recombinations and bubble growth during reionization (2005, background): “Although the optical depth only limits the global neutral fraction to be x̄H I 10−3 (Fan et al. 2002; Songaila 2004; Oh & Furlanetto 2005), its rapid evolution may be characteristic of the tail end of reionization (Gnedin 2000; Razoumov et al. 2002).”
Consistent modelling of the meta-galactic UV background and the thermal/ionization history of the intergalactic medium (2018, background): “…studies of Lyman-α absorption in the spectra of distant quasars showed that hydrogen is fully ionized at least out to z ' 5.6, while inhomogeneous reionization may be still ongoing at slightly earlier times, z ' 6 (e.g., Fan et al. 2006; Songaila 2004; Becker et al. 2015; McGreer et al. 2015).”