A SPECTROSCOPIC REDSHIFT MEASUREMENT FOR A LUMINOUS LYMAN BREAK GALAXY AT z = 7.730 USING KECK/MOSFIRE

By P. Oesch, P. V. van Dokkum, G. Illingworth, R. Bouwens, Ivelina G. Momcheva, B. Holden, G. Roberts-Borsani, R. Smit, M. Franx, I. Labbé and 2 more. 2015

145 citations recorded by the source corpus.

We present a spectroscopic redshift measurement of a very bright Lyman break galaxy at z = 7.7302 ± 0.0006 ?> using the Keck/Multi-Object Spectrometer for Infra-Red Exploration. The source was pre-selected photometrically in the EGS field as a robust z ∼ 8 candidate with H = 25.0 mag based on optical non-detections and a very red Spitzer/IRAC [3.6]–[4.5] broad-band color driven by high equivalent width [O iii]+Hβ line emission. The Lyα line is reliably detected at 6.1 &sgr; ?> and shows an asymmetric profile as expected for a galaxy embedded in a relatively neutral intergalactic medium near the Planck peak of cosmic reionization. The line has a rest-frame equivalent width of EW 0 = 21 ± 4 ?> Å and is extended with V FWHM = 360 − 70 + 90 ?> km s−1. The source is perhaps the brightest and most massive z ∼ 8 Lyman break galaxy in the full CANDELS and BoRG/HIPPIES surveys, having already assembled 10 9.9 ± 0.2 M ⊙ ?> of stars at only 650 Myr after the Big Bang. The spectroscopic redshift measurement sets a new redshift record for galaxies. This enables reliable constraints on the stellar mass, star formation rate, and formation epoch, as well as combined [O iii]+Hβ line equivalent widths. The redshift confirms that the IRAC [4.5] photometry is very likely dominated by line emission with EW0([O iii]+Hβ) = 720 − 150 + 180 ?> Å. This detection thus adds to the evidence that extreme rest-frame optical emission lines are a ubiquitous feature of early galaxies promising very efficient spectroscopic follow-up in the future with infrared spectroscopy using the James Webb Space Telescope and, later, ELTs.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/693d85f5c063fda87c752504d242bdd4ab20580c

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In Astronomy and Astrophysics

1. P. V. van Dokkum
2. Richard S. Ellis
3. M. Franx
4. P. Oesch
5. R. Bouwens
6. G. Illingworth
7. I. Labbé
8. M. Ouchi

In Instrumentation

1. P. V. van Dokkum
2. M. Franx
3. Richard S. Ellis
4. R. Bouwens
5. I. Labbé
6. P. Oesch
7. G. Illingworth
8. J. Dunlop

Citations in the corpus

• Lyα and C iii] emission in z = 7–9 Galaxies: accelerated reionization around luminous star-forming systems? (2016, background): “…IRAC flux excess, in the same manner as earlier studies (Shim et al. 2011; Stark et al. 2013; Smit et al. 2014, 2015a; Roberts-Borsani et al. 2016), The spectroscopic redshift was confirmed by Oesch et al. (2015) through detection of a strong Lyα emission line using MOSFIRE (see Figure 1a).”
• The Universe Is Reionizing at z ∼ 7: Bayesian Inference of the IGM Neutral Fraction Using Lyα Emission from Galaxies (2017, background): “…galaxies at z > 7.5 with strong Spitzer/IRAC excesses have recently been observed with Lyα (Finkelstein et al. 2013; Roberts-Borsani et al. 2016; Oesch et al. 2015; Zitrin et al. 2015; Stark et al. 2017), at a redshift when the IGM is expected to be significantly neutral (Planck Collaboration…”
• CONTRASTING GALAXY FORMATION FROM QUANTUM WAVE DARK MATTER, ψDM, WITH ΛCDM, USING PLANCK AND HUBBLE DATA (2015, background): “Exceptions have been found with strong Lyα emission at ~z 7.7 (Oesch et al. 2015), and also the currently highest redshift galaxy established by spectroscopy at ~z 8.7 (Zitrin et al. 2015).”
• FORMING COMPACT MASSIVE GALAXIES (2015, methodology): “The data reduction used the standard MOSFIRE pipeline DRP,11 with small modifications (see Oesch et al. 2015).”
• Systematic Identification of LAEs for Visible Exploration and Reionization Research Using Subaru HSC (SILVERRUSH). I. Program strategy and clustering properties of ∼2000 Lyα emitters at z = 6–7 over the 0.3–0.5 Gpc2 survey area (2017, background): “Recent deep spectroscopy also detected strong Lyα emission of ∼10 LAEs at z = 7.0–8.7, pushing the redshift frontier of LAEs to-date (e.g., Pentericci et al. 2011; Ono et al. 2012; Shibuya et al. 2012; Finkelstein et al. 2013; Schenker et al. 2014; Oesch et al. 2015; Zitrin et al. 2015).”
• EVIDENCE FOR PopIII-LIKE STELLAR POPULATIONS IN THE MOST LUMINOUS Lyα EMITTERS AT THE EPOCH OF REIONIZATION: SPECTROSCOPIC CONFIRMATION (2015, background): “…handful of galaxies and quasars at z > 6.5 (e.g. Mortlock et al. 2011; Ono et al. 2012; Schenker et al. 2014; Finkelstein et al. 2013; Pentericci et al. 2014; Oesch et al. 2015), for both physical (galaxies becoming increasingly fainter) and observational reasons (the need for deep near-infrared…”
• Observational evidence for intermediate-mass black holes (2017, unknown): “…a strong Ly α emission line, virtually the only line available to confirm high redshifts, has been commonly used to detect galaxies at z > 6 (e.g., Ouchi et al. 2009, 2010; Finkelstein et al. 2013; Oesch et al. 2015) and has recently emerged as another powerful tool to discover seed BHs at high-z.”
• The assembly of ‘normal’ galaxies at z ∼ 7 probed by ALMA (2015, background): “We also note that z∼7.7 is the maximum redshift at which galaxies are spectroscopically confirmed (Oesch et al. 2015) and we recall that, even with the broad ALMA band, a spectroscopic redshift is needed to observe far-IR transitions redshifted into the millimeter band.”
• Inferences on the timeline of reionization at z ∼ 8 from the KMOS Lens-Amplified Spectroscopic Survey (2019, methodology): “In Figure 5 we plot the posterior distribution for xhi obtained using our observations of the 29 z ∼ 8 KLASS targets, as well as Keck/MOSFIRE observations of 8 z ∼ 8 LBGs from the Brightest of Reionizing Galaxies survey (BoRG, Trenti et al. 2011; Bradley et al. 2012; Schmidt et al. 2014b) described ”
• Big Three Dragons: A z = 7.15 Lyman-break galaxy detected in [O iii] 88 μm, [C ii] 158 μm, and dust continuum with ALMA (2018, background): “• We have investigated the IRX-β relation at z≈ 6.5−9.1 based on eleven spectroscopically identified objects including five LBGs with dust continuum detections.”
• An extreme [O III] emitter at z = 3.2: a low metallicity Lyman continuum source (2015, background): “From the very large EW([O iii]λλ4959, 5007+Hβ) observed at high-redshift (Oesch et al. 2015; Zitrin et al. 2015; Roberts-Borsani et al. 2015; Smit et al. 2015), we can speculate that these galaxies have a leakage of ionizing photons.”
• Stellar population effects on the inferred photon density at reionization (2015, background): “…redshift galaxies are typically limited to their broadband colours in the rest-frame ultraviolet (and sometimes optical) and perhaps a measurement of particularly strong emission lines (such as Lyman-α at 1216Å; e.g. Labbé et al. 2013; Caruana et al. 2014; Oesch et al. 2015; Smit et al. 2015).”
• SILVERRUSH. IV. Lyα luminosity functions at z = 5.7 and 6.6 studied with ∼1300 Lyα emitters on the 14–21 deg2 sky (2017, background): “…et al. 2010; Shibuya et al. 2012; Yamada et al. 2012; Konno et al. 2014) and spectroscopic observations (e.g., Deharveng et al. 2008; Adams et al. 2011; Finkelstein et al. 2013; Schenker et al. 2014; Cassata et al. 2015; Oesch et al. 2015; Zitrin et al. 2015; Song et al. 2016; Stark et al. 2017).”