Spectroscopic Confirmation of Three Redshift z ≈ 5.7 Lyα Emitters from the Large-Area Lyman Alpha Survey

By J. Rhoads, A. Dey, S. Malhotra, Daniel Stern, H. Spinrad, B. Jannuzi, S. Dawson, Michael J. I. Brown, Emily Landes. 2002

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Narrowband searches for Lyα emission are an efficient way of identifying star-forming galaxies at high redshifts. We present Keck Telescope spectra confirming redshifts z ≈ 5.7 for three objects discovered in the Large-Area Lyman Alpha (LALA) survey at Kitt Peak National Observatory. All three spectra show strong, narrow emission lines with the asymmetric profile that is characteristically produced in high-redshift Lyα emitters by preferential H I absorption in the blue wing of the line. These objects are undetected in deep BW, V, R, and λ ≈ 6600 Å narrowband images from the NOAO Deep Wide-Field Survey and from LALA, as expected from Lyman break and Lyα forest absorption at redshift z ≈ 5.7. All three objects show large equivalent widths (≳150 Å in the rest frame), suggesting at least one of the following: a top-heavy initial mass function, very low stellar metallicity, or the presence of an active nucleus. We consider the case for an active nucleus to be weak in all three objects due to the limited width of the Lyα emission line (less than 500 km s-1) and the absence of any other indicator of quasar activity. The three confirmed high-redshift objects were among four spectroscopically observed targets drawn from the sample of 18 candidates presented by Rhoads & Malhotra. Thus, these spectra support the Lyα emitter population statistics from our earlier photometric study, which imply little evolution in number density from z = 5.7 to 4.5 and provide strong evidence that the reionization redshift is zr > 5.7.

Subfields: Astronomy and Astrophysics, Instrumentation

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Citations in the corpus

Luminosity Functions of Lyα Emitters at Redshifts z = 6.5 and z = 5.7: Evidence against Reionization at z ≤ 6.5 (2004, methodology): “THE Lya LUMINOSITY FUNCTIONz p 5.7 We base our LF fit on a combination of four surveys:z p 5.7 The Large-Area Lyman Alpha (LALA) survey (RM01; Rhoads et al. 2003), Hu et al. (2004), Ajiki et al. (2004), and Santos et al. (2004), summarized in Table 1.”
Identification of the brightest Lyα emitters at z = 6.6 : Implications for the evolution of the luminosity function in the reionization era (2015, background): “Samples of LAEs have now been established from z ∼ 2 − 7 through narrow-band surveys (e.g. Cowie & Hu 1998; Rhoads et al. 2000; Fynbo et al. 2001; Rhoads et al. 2003; Malhotra & Rhoads 2004; Taniguchi et al. 2005; Shimasaku et al. 2006; Westra et al. 2006; Nilsson et al. 2007; Ouchi et al. 2008,…”
Lyα Emitters at z = 5.7 in the Subaru Deep Field (2006, methodology): “…expected to be small (SW is measured for the doublet as a whole); for all resolved [Oii] emitters in our sample, the λ3726 line is weaker than the λ3729 line, 1 This pipeline was developed at UC Berkeley with support from NSF grant AST-0071048. meaning a negative SW (See also Rhoads et al. 2003).”
The End of the Reionization Epoch Probed by Lyα Emitters at z = 6.5 in the Subaru Deep Field (2006, methodology): “This statistic is free from fitting procedures such as the aλ and af presented by Rhoads et al. (2003).”
Observational Constraints on Cosmic Reionization (2006, background): “Malhotra & Rhoads (2004) and Stern et al. (2004) combined the LALA survey of Lyα galaxies (Rhoads et al. 2003) with other Lyα surveys in the literature to determine the luminosity function of Lyα galaxies at z = 6.5 and 5.7.”
The SUBARU Deep Field Project: Lymanα Emitters at a Redshift of 6.6 (2004, background): “Rhoads and Malhotra (2001) also carried out a similar survey for z=5.7 LAEs; the limiting luminosity of their survey, ≈ 5.3× 1042 h−20.7 erg s −1, is brighter than ours (see also Rhoads et al. 2003) .”
Unusually Large Fluctuations in the Statistics of Galaxy Formation at High Redshift (2003, background): “For example, there are a large number of programs searching for galaxies at the highest accessible redshifts (6.5 and beyond) using their strong Lyα emission (Hu et al. 2002; Rhoads et al. 2003; Maier et al. 2003; Kodaira et al. 2003).”
SPECTROSCOPIC CONFIRMATION OF THREE z-DROPOUT GALAXIES AT z = 6.844–7.213: DEMOGRAPHICS OF Lyα EMISSION IN z ∼ 7 GALAXIES (2011, background): “When the [Oii] line is not resolved, its Sw value is expected to be small, since the [Oii]λ3726 line is weaker than [Oii]λ3729 (e.g., Rhoads et al. 2003).”
Protoclusters associated with z > 2 radio galaxies - I. Characteristics of high redshift protoclusters (2006, methodology): “What makes this test extra useful is that a blended [Oii] doublet would appear as a single line withexcessemission on the blue side, because the redder line of the doublet is stronger in star forming galaxies (Rhoads et al., 2003).”