SPECTROSCOPIC CONFIRMATION OF TWO LYMAN BREAK GALAXIES AT REDSHIFT BEYOND 7

By E. Vanzella, L. Pentericci, A. Fontana, A. Grazian, M. Castellano, K. Boutsia, S. Cristiani, Mark Dickinson, S. Gallozzi, E. Giallongo and 5 more. 2010

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We report the spectroscopic confirmation of two Lyman break galaxies at redshift >7. The galaxies were observed as part of an ultra-deep spectroscopic campaign with FORS2 at the ESO/VLT for the confirmation of z ≃ 7 “z-band dropout” candidates selected from our VLT/Hawk-I imaging survey. Both galaxies show a prominent emission line at 9735 Å and 9858 Å, respectively: the lines have fluxes of ∼(1.6–1.2) × 10−17 erg s−1 cm−2 and exhibit a sharp decline on the blue side and a tail on the red side. The asymmetry is quantitatively comparable to the observed asymmetry in z ∼ 6 Lyα lines, where absorption by neutral hydrogen in the intergalactic medium (IGM) truncates the blue side of the emission-line profile. We carefully evaluate the possibility that the galaxies are instead at lower redshift and we are observing either [O ii], [O iii], or Hα emission: however from the spectroscopic and the photometric data we conclude that there are no other plausible identifications, except for Lyα at redshift >7, implying that these are two of the most robust redshift determination for galaxies in the reionization epoch. Based on their redshifts and broadband photometry, we derive limits on the star formation rate and on the ultraviolet spectral slopes of the two galaxies. We argue that these two galaxies alone are unlikely to have ionized the IGM in their surroundings.

Subfields: Astronomy and Astrophysics, Electrical and Electronic Engineering, Instrumentation

View Paper: https://www.semanticscholar.org/paper/2b8da9023647125609b212fc5bc2ef7d6aa1a220

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Citations in the corpus

CONNECTING THE GAMMA RAY BURST RATE AND THE COSMIC STAR FORMATION HISTORY: IMPLICATIONS FOR REIONIZATION AND GALAXY EVOLUTION (2011, background): “Recent spectroscopic campaigns have begun to confirm that many of these sources do indeed lie atz & 7 (e.g., Iye et al. 2006; Stark et al. 2010; Lehnert et al. 2010; Fontana et al. 2010; Vanzella et al. 2011; Schenker et al. 2011; Pentericci et al. 2011; Ono et al. 2011).”
NEW OBSERVATIONS OF z ∼ 7 GALAXIES: EVIDENCE FOR A PATCHY REIONIZATION (2014, result): “…works, a lack of Lyα emission was found at z ∼ 7 compared to z ∼ 6 by several independent teams: in our previous observations (Pentericci et al. 2011; Vanzella et al. 2011; Fontana et al. 2010; P11, V11 and F10 from here on) we found 4 Lyα emitting galaxies (plus another object with a tentative…”
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, result): “Some evidence for this is seen in the recent studies of Fontana et al. (2010) and Vanzella et al. (2011).”
Inferences on the timeline of reionization at z ∼ 8 from the KMOS Lens-Amplified Spectroscopic Survey (2019, methodology): “…resolution) for current detections of Lyα in z > 7 LBGs (Oesch et al. 2015; Roberts-Borsani et al. 2016; Stark et al. 2017; Zitrin et al. 2015; Song et al. 2016a; Finkelstein et al. 2013; Shibuya et al. 2012; Ono et al. 2012; Schenker et al. 2012; Vanzella et al. 2011; Laporte et al. 2017a).”
The Universe Is Reionizing at z ∼ 7: Bayesian Inference of the IGM Neutral Fraction Using Lyα Emission from Galaxies (2017, background): “…spanning UV magnitudes −22.75∼<Muv∼< − 17.8 and include 10 intrinsically faint objects gravitationally lensed behind the Bullet Cluster (Bradač et al. 2012) as well as observations in deep HST legacy fields (Fontana et al. 2010; Vanzella et al. 2011; Ono et al. 2012; Schenker et al. 2012).”
SPECTROSCOPIC CONFIRMATION OF z ∼ 7 LYMAN BREAK GALAXIES: PROBING THE EARLIEST GALAXIES AND THE EPOCH OF REIONIZATION (2011, methodology): “The first results were published in F10 where we reported the confirmation of a weak Lyα emission line at z = 6.97 in the GOODS-South field, and in Vanzella et al. 2011 (V11) were we presented two galaxies in the BDF-4 field, showing bright Lyα emission at z ≈ 7.1.”
Ionization state of inter-stellar medium in galaxies: evolution, SFR-M * -Z dependence, and ionizing photon escape (2013, background): “This could be due to the Lyα damping absorption of partly neutral IGM (Pentericci et al. 2011; Vanzella et al. 2011; Ono et al. 2012; Schenker et al. 2012) or optically thick systems in the intervening IGM (Bolton & Haehnelt 2013).”
An extreme [O III] emitter at z = 3.2: a low metallicity Lyman continuum source (2015, methodology): “Reduction has been done as described in Balestra et al. (2010) as well as adopting the AB-BA method described in Vanzella et al. (2011, 2014b).”
Lyα and C iii] emission in z = 7–9 Galaxies: accelerated reionization around luminous star-forming systems? (2016, background): “…a large investment has been devoted to searches for Lyα emission in the reionization era, resulting in only nine robust detections of Lyα at z > 7 (Vanzella et al. 2011; Ono et al. 2012; Schenker et al. 2012; Shibuya et al. 2012; Finkelstein et al. 2013; Oesch et al. 2015; Zitrin et al. 2015;…”
CANDELS: THE COSMIC ASSEMBLY NEAR-INFRARED DEEP EXTRAGALACTIC LEGACY SURVEY (2011, unknown): “Current attempts have already yielded plausible single-line detections (Lehnert et al. 2010; Vanzella et al. 2011) and useful upper limits (Fontana et al. 2010).”
SPECTROSCOPIC CONFIRMATION OF THREE z-DROPOUT GALAXIES AT z = 6.844–7.213: DEMOGRAPHICS OF Lyα EMISSION IN z ∼ 7 GALAXIES (2011, methodology): “We estimate the Lyα fraction of z-dropout galaxies from Vanzella et al. (2011) and Pentericci et al. (2011) to be X25Lyα = 22 +18 −17% (2/9) and X55Lyα = 11 +12 −11% (1/9) for UV-bright galaxies at z ∼ 7.”
A critical analysis of the ultraviolet continuum slopes (β) of high-redshift galaxies: no evidence (yet) for extreme stellar populations at z > 6 (2011, methodology): “…hasnow been successfully used to discover galaxies atz ≃ 6.5 − 8.5 (e.g. McLure et al. 2010; Oesch et al. 2010; Bouwens et al. 2010a; Bunker et al. 2010; Finkelstein et al. 2010; Vanzella et al. 2011) can actually be used to establish the rest-frame continuum slope f the highest redshift galaxies.”
The galaxy stellar mass function at 3.5 ≤z ≤ 7.5 in the CANDELS/UDS, GOODS-South, and HUDF fields (2015, result): “Additional spectroscopic redshifts were added to the present sample by a collection of high-redshift LBGs from Fontana et al. (2010), Vanzella et al. (2011), Pentericci et al. (2011) and preliminary results of the ESO Large Programme (PI L. Pentericci) with 140 expected A96, page 4 of 25 hours of…”
The assembly of ‘normal’ galaxies at z ∼ 7 probed by ALMA (2015, background): “This is probably significantly in excess (even by a few 100 km/s) with respect to the real systemic redshift of the sources, because of IGM absorption of the blue side of Lyα.”
A SPECTROSCOPIC REDSHIFT MEASUREMENT FOR A LUMINOUS LYMAN BREAK GALAXY AT z = 7.730 USING KECK/MOSFIRE (2015, background): “Currently, only a handful of normal galaxies have reliably measured redshifts at z > 7 (see, e.g., Vanzella et al. 2011; Pentericci et al. 2011; Ono et al. 2012; Schenker et al. 2012; Shibuya et al. 2012; Finkelstein et al. 2013), with most 1 Yale Center for Astronomy and Astrophysics, Physics…”
Spectroscopic detections of C iii] λ1909 Å at z ≃ 6–7: a new probe of early star-forming galaxies and cosmic reionization (2014, background): “At the time of writing there are fewer than 10 spectroscopically-confirmed galaxies beyond z ' 7 (Vanzella et al. 2011; Ono et al. 2012; Schenker et al. 2012; Finkelstein et al. 2013; Schenker et al. 2014). and no convincing example beyond z = 7.62.”