A DEFINITIVE SURVEY FOR LYMAN LIMIT SYSTEMS AT z ∼ 3.5 WITH THE SLOAN DIGITAL SKY SURVEY

By J. Xavier Prochaska, John M. O’Meara, G. Worseck. 2009

142 citations recorded by the source corpus.

We perform a semi-automated survey for τ912 ⩾ 2 Lyman limit systems (LLSs) in quasar spectra from the Sloan Digital Sky Survey, Data Release 7. From a starting sample of 2473 quasars with z em = 3.6–5.0, we analyze 429 spectra meeting strict selection criteria for a total redshift path Δz = 93.8 and identify 190 intervening systems at z LLS ⩾ 3.3. The incidence of τ912 ⩾ 2 LLSs per unit redshift, ℓτ⩾2(z), is well described by a single power law at these redshifts: , with z * ≡ 3.7, C LLS = 1.9 ± 0.2, and γLLS = 5.1 ± 1.5 (68% c.l.). These values are systematically lower than previous estimates (especially at z < 4) but are consistent with recent measurements of the mean free path to ionizing radiation. Extrapolations of this power law to z = 0 are inconsistent with previous estimations of ℓ(z) at z < 1 and may indicate a break at z ≈ 2, similar to that observed for the Lyα forest. Our results also indicate that the systems giving rise to LLS absorption decrease by ≈50% in comoving number density and/or physical size from z = 4 to 3.3, perhaps due to an enhanced extragalactic ultraviolet background. The observations place an integral constraint on the H i frequency distribution f(N H i , X) and indicate that the power-law slope is likely shallower than β = −1 at . Including other constraints on f(N H i , X) from the literature, we infer that β is steeper than β = −1.7 at , implying at least two inflections in f(N H i , X). We also perform a survey for proximate LLSs (PLLSs) and find that ℓPLLS(z) is systematically lower (≈25%) than intervening systems. Finally, we estimate that systematic effects impose an uncertainty of 10%–20% in the ℓ(z) measurements; these effects may limit the precision of all future surveys.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/229f7fd2a5e2b109572f420f39b926b7670b4ca0

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

In Astronomy and Astrophysics

Citations in the corpus

Absorption-line systems in simulated galaxies fed by cold streams (2011, methodology): “10, we report the preferred model from Prochaska et al. (2010).”
THE EVOLUTION OF LYMAN LIMIT ABSORPTION SYSTEMS TO REDSHIFT SIX (2010, unknown): “(5) 3.3 – 4.4 469 192 5.2± 1.5 1.5± 0.2 · · · a References: (1) Péroux (2001); (2) Stengler-Larrea et al. (1995); (3) Storrie-Lombardi et al. (1994); (4) SSB (1989); (5) Prochaska et al. (2010). b Refers to number of LLS with τ > 1, except for Ref.”
Inhomogeneous recombinations during cosmic reionization (2014, methodology): “Radiative transfer calculations (McQuinn et al. 2011; Rahmati et al. 2013), together with observations of quasar Lyα spectra (e.g. Prochaska et al. 2010; Songaila & Cowie 2010), confirm that the general properties of LLSs can be understood in terms of the local Jeans length (Schaye 2001), although…”
The Giant Gemini GMOS survey of zem > 4.4 quasars – I. Measuring the mean free path across cosmic time (2014, background): “In fact, one measures a lower incidence of optically thick LLSs within the proximity zones of zem ∼ 4 quasars (Prochaska et al. 2010).”
ON LYMAN-LIMIT SYSTEMS AND THE EVOLUTION OF THE INTERGALACTIC IONIZING BACKGROUND (2011, background): “1017.5 cm−2 as the observations of Prochaska et al. (2010) suggest, collisional ionization is likely the only means to significantly weaken the dependence of Γ on ǫ from the scaling in equation (4).”
The Neutral Hydrogen Cosmological Mass Density at z = 5 (2015, background): “The remnants of such regions may be observable as Lyman limit systems however, and so one might expect an increase in their incidence rate towards z ∼ 5, which observations already hint may be the case (Prochaska et al. 2010; Fumagalli et al. 2013).”
Evolution of the AGN UV luminosity function from redshift 7.5 (2018, background): “We note, however, that at z >∼ 3.5 all UV background synthesis models are based on brazen extrapolations of f (NH i, z), whose detailed shape for (partial) Lyman limit systems is not well constrained at these redshifts (Prochaska et al. 2010).”
An updated analytic model for attenuation by the intergalactic medium (2014, background): “However, recent observations suggest a break of the column density distribution around NHI ∼ 1017 cm−2 (Prochaska et al. 2005, 2010; O’Meara et al. 2013); the slope changes from a steeper at a lower column density to a shallower at a higher column density.”
New Measurements of the Ionizing Ultraviolet Background over 2 < z < 5 and Implications for Hydrogen Reionization (2013, background): “1020 cm−2) (e.g., O’Meara et al. 2007; Prochaska et al. 2010).”
Stellar population gradients in galaxy discs from the CALIFA survey - The influence of bars (2014, background): “…gradients have mainly Article published by EDP Sciences A6, page 1 of 85 been investigated using colours (e.g., de Jong 1996; Peletier & Balcells 1996; Jansen et al. 2000; Bell & de Jong 2000; MacArthur et al. 2004; Taylor et al. 2005; Muñoz-Mateos et al. 2007, 2009; Prochaska et al. 2010).”
Concordance models of reionization: implications for faint galaxies and escape fraction evolution (2012, background): “(10)) is valid at least up to z ∼ 4, where the column density distribution has been measured to be well approximated by a series of power laws (Prochaska et al. 2010).”
Measurements of the UV background at 4.6 < z < 6.4 using the quasar proximity effect (2010, background): “Indeed Prochaska et al. (2010) note that both of those papers are subject to biases that they claim have notbeen adequately compensated for, and so they may have overestimated N(z) by up to a factor of 3.”
RADIATIVE TRANSFER IN A CLUMPY UNIVERSE. IV. NEW SYNTHESIS MODELS OF THE COSMIC UV/X-RAY BACKGROUND (2011, background): “The procedure yields the slopes β = 0.47, 0.61, 0.72, 0.82 at redshifts z = 2, 3, 4, 5, respectively, in agreement with Prochaska et al. (2010) who find for the LSSs β = 0.8+0.4−0.2 at z ≈ 3.5.”
A refined measurement of the mean transmitted flux in the Lyα forest over 2 < z < 5 using composite quasar spectra (2012, methodology): “We use the broken powerlaw column density distribution at z ∼ 3.7 compiled by Prochaska et al. (2010), and adopt 1019 cm−2 and 1022 cm−2 as our limits of integration.”