Keck Spectroscopy of Faint 3<z<7 Lyman Break Galaxies:- II. A High Fraction of Line Emitters at Redshift Six

By D. Stark, Richard S. Ellis, M. Ouchi. 2010

188 citations recorded by the source corpus.

As Lyman-alpha photons are scattered by neutral hydrogen, a change with redshift in the Lyman-alpha equivalent width distribution of distant galaxies offers a promising probe of the degree of ionization in the intergalactic medium and hence when cosmic reionization ended. This simple test is complicated by the fact that Lyman-alpha emission can also be affected by the evolving astrophysical details of the host galaxies. In the first paper in this series, we demonstrated both a luminosity and redshift dependent trend in the fraction of Lyman-alpha emitters seen within color-selected Lyman-break galaxies (LBGs) over the range 3<z<6; lower luminosity galaxies and those at higher redshift show an increased likelihood of strong emission. Here we present the results from much deeper 12.5 hour exposures with the Keck DEIMOS spectrograph focused primarily on LBGs at z~6 which enable us to confirm the redshift dependence of line emission more robustly and to higher redshift than was hitherto possible. We find 54+/-11% of faint z~6 LBGs show strong (W_0>25 A) emission, an increase of 1.6x from a similar sample observed at z~4. With a total sample of 74 z~6 LBGs, we determine the luminosity-dependent Lyman-alpha equivalent width distribution. Assuming continuity in these trends to the new population of z~7 sources located with the Hubble WFC3/IR camera, we predict that unless the neutral fraction rises in the intervening 200 Myr, the success rate for spectroscopic confirmation using Lyman-alpha emission should be high.

Subfields: Astronomy and Astrophysics, Electrical and Electronic Engineering, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/eb8a20a849f3dd80490638206dee68faa7919460

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Citations in the corpus

REIONIZATION AFTER PLANCK: THE DERIVED GROWTH OF THE COSMIC IONIZING EMISSIVITY NOW MATCHES THE GROWTH OF THE GALAXY UV LUMINOSITY DENSITY (2015, background): “Assuming that the prevalence of Lyα emission in star-forming galaxies at z ∼ 6.5–8 is a simple extrapolation of the observed prevalence at z ∼ 4–6 and any departures from these trends are due to an increasingly neutral IGM at z ∼ 7–8, one can use this technique to quantify the filling factor of ioni”
A SPECTROSCOPIC REDSHIFT MEASUREMENT FOR A LUMINOUS LYMAN BREAK GALAXY AT z = 7.730 USING KECK/MOSFIRE (2015, background): “…rate of spectroscopic follow-up surveys is likely caused by a decreased fraction of galaxies showing strong Lyα emission due to an increased neutral fraction in the inter-galactic medium (IGM) at z > 6 (Stark et al. 2010, 2011; Treu et al. 2013; Schenker et al. 2012, 2014; Pentericci et al. 2014).”
Ionization state of inter-stellar medium in galaxies: evolution, SFR-M * -Z dependence, and ionizing photon escape (2013, background): “…observations reveal that a fraction of LAEs to star-forming galaxies of LBGs increases with redshift (e.g. Ouchi et al. 2008; Vanzella et al. 2009; Stark et al. 2010; Stark, Ellis & Ouchi 2011), more LAEs with a high ionization parameter, i.e. a high fesc, would ease the tension of the deficit of…”
SPECTROSCOPIC CONFIRMATION OF THREE z-DROPOUT GALAXIES AT z = 6.844–7.213: DEMOGRAPHICS OF Lyα EMISSION IN z ∼ 7 GALAXIES (2011, background): “We also show, as shaded area, an extrapolation of lower-z Lyα fraction to z ∼ 7, which is derived by Stark et al. (2011).”
NEW OBSERVATIONS OF z ∼ 7 GALAXIES: EVIDENCE FOR A PATCHY REIONIZATION (2014, methodology): “In Table 2 we report the fraction of galaxies having and EW > 25 Å and > 50 Å separately for the two absolute magnitude bins that were adopted by previous works (Stark et al. 2010, P11, Ono et al. 2012).”
LINE-EMITTING GALAXIES BEYOND A REDSHIFT OF 7: AN IMPROVED METHOD FOR ESTIMATING THE EVOLVING NEUTRALITY OF THE INTERGALACTIC MEDIUM (2014, methodology): “Thus, for all other objects, we must predict EWLyα as a function of MUV from Treu et al. (2012), using the data presented in Stark et al. (2011).”
New Measurements of the Ionizing Ultraviolet Background over 2 < z < 5 and Implications for Hydrogen Reionization (2013, background): “…dependence of Lyα emission (Stark et al. 2010, 2011), but we note that if we assume c© 0000 RAS, MNRAS 000, 000–000 that zero per cent of LBGs brighter than M = −20.25 (the bright sample of Stark et al. (2011)) are LAEs, then the above value for ǫSFG912 would only decrease by 16 per cent.”
The Universe Is Reionizing at z ∼ 7: Bayesian Inference of the IGM Neutral Fraction Using Lyα Emission from Galaxies (2017, background): “Indeed we get the same results, within the uncertainties, if we use the p6(W ) truncated Gaussian distribution from Treu et al. (2012) based on the sample presented in Stark et al. (2011).”
CANDELS: THE CONTRIBUTION OF THE OBSERVED GALAXY POPULATION TO COSMIC REIONIZATION (2012, background): “Additionally, the fraction of galaxies exhibiting Lyα emission (with a rest-frame Lyα equivalent width> 20 Å) rises with redshift, from∼25% atz∼ 3 (e.g., Shapley et al. 2003) to& 60% atz∼ 6 (e.g., Stark et al. 2010, 2011).”
Inferences on the timeline of reionization at z ∼ 8 from the KMOS Lens-Amplified Spectroscopic Survey (2019, background): “…spanning opposite ends of the galaxy UV luminosity function: the IGM attenuation of Lyα from UV bright and UV faint galaxies is expected to be different due to differing Lyα escape paths through their interstellar and circumgalactic media (e.g., Stark et al. 2010, 2017; Mason et al. 2018b).”
KECK SPECTROSCOPY OF FAINT 3 < z < 8 LYMAN BREAK GALAXIES: EVIDENCE FOR A DECLINING FRACTION OF EMISSION LINE SOURCES IN THE REDSHIFT RANGE 6 < z < 8 (2011, background): “In Stark et al. (2011) (hereafter Paper II), through ultra-deep exposures with DEIMOS we significantly im- proved the line emission statistics at z ≃ 6, providing a robust measure of the rest-frame EW distribution of Lyα emission at the highest redshift when the Universe is believed to be fully…”
Ultraviolet emission lines in young low-mass galaxies at z ≃ 2: physical properties and implications for studies at z > 7 (2014, background): “With observations indicating thatLyα becomes more common in galaxies at earlier times over the redshift range3 ∼< z ∼< 6 (Stark et al. 2010, Stark et al. 2011), we may expect large equivalent width CIII] emission to become ubiqitous among the galaxy population atz ∼> 6.”
Extragalactic science, cosmology, and Galactic archaeology with the Subaru Prime Focus Spectrograph (2012, background): “25) (e.g., Ouchi et al. 2010) and the complementary measure of the fraction of galaxies with Lyα emission, with unprecedented large samples of LAEs and LBGs, respectively (Stark et al. 2011).”