Spectroscopy of z ∼ 7 candidate galaxies: using Lyman α to constrain the neutral fraction of hydrogen in the high-redshift universe★

Caruana, Joseph; Bunker, Andrew J.; Wilkins, Stephen M.; Stanway, Elizabeth R.; Lorenzoni, Silvio; Jarvis, Matt J.; Ebert, Holly

doi:10.1093/mnras/stu1341

Cited by 166 publications

(150 citation statements)

References 53 publications

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“…In both models, however, the low-velocity offset is a consequence of the presence of low HI-column density escape routes for Lyα photons, which may also allow ionizing photons to escape (see Verhamme et al 2015Verhamme et al , 2017Dijkstra et al 2016 for more detailed discussions). For a more general conclusion, a larger sample is needed, but if future observations systematically show smaller velocity offsets, this would imply that the observed drop in LAE fraction between z∼6 and 7 (e.g., Schenker et al 2012Schenker et al , 2014Caruana et al 2014;Pentericci et al 2014;Tilvi et al 2014;Schmidt et al 2016) is more easily explained by changes in the IGM than in the circumgalactic medium or galactic intrinsic properties (Dijkstra 2014;Choudhury et al 2015;Mesinger et al 2015).…”

Section: Resultsmentioning

confidence: 99%

ALMA [C ii] 158 μm Detection of a Redshift 7 Lensed Galaxy behind RX J1347.1−1145*

Bradač

Garcia‐Appadoo

Huang

et al. 2017

ApJL

107

129

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We present the results of ALMA spectroscopic follow-up of a z=6.766 Lyα emitting galaxy behind the cluster RX J1347.1−1145. We report the detection of [C II] 158 μm line fully consistent with the Lyα redshift and with the peak of the optical emission. Given the magnification of μ=5.0±0.3, the intrinsic (corrected for lensing) luminosity of the, roughly ∼5 times fainter than other detections of z∼7 galaxies. The result indicates that low L [C II] in z∼7 galaxies compared to the local counterparts might be caused by their low metallicities and/or feedback. ) between the Lyα and [C II] line is unusual, and may be indicative of ionizing photons escaping.

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Section: Resultsmentioning

confidence: 99%

ALMA [C ii] 158 μm Detection of a Redshift 7 Lensed Galaxy behind RX J1347.1−1145*

Bradač

Garcia‐Appadoo

Huang

et al. 2017

ApJL

107

129

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“…In addition to the large amount of telescope time needed to reach the required depth, the absence of Lyα emission does not exclude the high-redshift nature of the associated objects. Indeed, the increasing neutral hydrogen fraction at z > 6 easily absorbs and diffuses Lyα photons (Atek et al 2009;Stark et al 2010;Caruana et al 2014;Schenker et al 2014). Therefore, one must rely on simulated colors based on galaxy spectral templates to estimate the contamination rate of low-redshift galaxies, which thus has been found to be less than 10% in most studies (e.g., Oesch et al 2010;Bouwens et al 2015b).…”

Section: Sources Of Contaminationmentioning

confidence: 99%

ARE ULTRA-FAINT GALAXIES ATz= 6–8 RESPONSIBLE FOR COSMIC REIONIZATION? COMBINED CONSTRAINTS FROM THE HUBBLE FRONTIER FIELDS CLUSTERS AND PARALLELS

Atek

Richard

Jauzac

et al. 2015

ApJ

211

229

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We use deep Hubble Space Telescope imaging of the Frontier Fields to accurately measure the galaxy rest-frame ultraviolet luminosity function (UV LF) in the redshift range z ∼ 6-8. We combine observations in three lensing clusters, A2744, MACS 0416, and MACS 0717, and their associated parallelfields to select high-redshift dropout candidates. We use the latest lensing models to estimate the flux magnification and the effective survey volume in combination with completeness simulations performed in the source plane. We report the detection of 227 galaxy candidates at z = 6-7 and 25 candidates at z ∼ 8. While the total survey area is about 4 arcmin 2 in each parallel field, it drops to about 0.6-1 arcmin 2 in the cluster core fields because of the strong lensing. We compute the UV LF at z ∼ 7 using the combined galaxy sample and perform Monte Carlo simulations to determine the best-fit Schechter parameters. We are able to reliably constrain the LF down to an absolute magnitude of M UV = −15.25, which corresponds to 0.005 L å . More importantly, we find that the faint-end slope remains steep down to this magnitude limit with 2.04 . Our results confirm the most recent results in deep blank fields but extend the LF measurements more than two magnitudes deeper. The UV LF at z ∼ 8 is not very well constrained below M UV = −18 owing to the small number statistics and incompleteness uncertainties. To assess the contribution of galaxies to cosmic reionization, we derive the UV luminosity density at z ∼ 7 by integrating the UV LF down to an observational limit of M UV = −15. We show that our determination of log(ρ UV ) = 26.2 ± 0.13 (erg s −1 Hz −1 Mpc −3 ) can be sufficient to maintain reionization with an escape fraction of ionizing radiation of f esc = 10%-15%. Future Hubble Frontier Fields observations will certainly improve the constraints on the UV LF at the epoch of reionization, paving the way to more ambitious programs using cosmic telescopes with the next generation of large aperture telescopes such as the James Webb Space Telescope and the European Extremely Large Telescope.

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“…Even if the detection of Lyman α at very high-redshift is challenging (e.g., Caruana et al 2014), the continuum of the brightest objects should be observable with extremely deep observations using current facilities, such as KMOS/VLT (Sharples et al 2004), FLAMINGOS-2/Gemini (Eikenberry et al 2006) and NIRSPEC/Keck (McLean et al 1998). …”

Section: Opticalmentioning

confidence: 99%

Frontier Fields: Combining HST, VLT, andSpitzerdata to explore thez~ 8 Universe behind the lensing cluster MACSJ0416.1−2403

Laporte

Streblyanska

Kim

et al. 2015

A&A

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Context. The Hubble Space Telescope (HST) Frontier Fields (HFFs) project started at the end of 2013 with the aim of providing extremely deep images of six massive galaxy clusters. One of the main goals of this program is to push several telescopes to their limits to provide the best current view of the earliest stages of the Universe. The analysis of the initial data has already demonstrated the huge capabilities of the program. Aims. We present a detailed analysis of z ∼ 8 objects behind the HFFs lensing cluster, MACSJ0416.1-2403, combining 0.3−1.6 µm imaging from HST, ground-based K s imaging from VLT HAWK-I, and 3.6 µm and 4.5 µm Spitzer Space Telescope. The images probe to 5σ depths of ≈29 AB for HST, 25.6 AB for HAWK-I, and ≈0.310 and 0.391 µJy at 3.6 and 4.5 µm, respectively. With these datasets, we assess the photometric properties of z ∼ 8 galaxies in this field, as well as their distribution in luminosity, to unprecedented sensitivity. Methods. We applied the classical Lyman break (LB) technique, which combines non detection criteria in bands blueward of the Lyman break at z ∼ 8 and color-selection in bands redward of the break. To avoid contamination by mid-z interlopers, we required a strong break between optical and near-infrared data. We determined the photometric properties of z ∼ 8 selected candidates using spectral energy distribution (SED)-fitting with standard library templates. The luminosity function at z ∼ 8 is computed using a Monte-Carlo method taking advantage of the SED-fitting results. A piece of cautionary information is gleaned from new deep optical photometry of a previously identified z ∼ 8 galaxy in this cluster, which is now firmly detected as a mid-z interloper with a strong ≈1.5 mag Balmer break (between F606W and F125W). Using the SED of this interloper, we estimated the contamination rate of our MACSJ0416.1−2403 sample, and that of previous samples in Abell 2744 that were based on HFF data, we highlight the dangers of pushing the LB technique too close to the photometry limits. Results. Our selection reliably recovers four objects with m F160W ranging from 26.0 to 27.9 AB that are located in modestamplification regions (µ < 2.4). Two of the objects display a secondary break between the IRAC 3.6 µm and 4.5 µm bands, which could be associated to the Balmer break or emission lines at z ∼ 8. The SED-fitting analysis suggests that all of these objects favor high-z solutions with no reliable secondary solutions. The candidates generally have star formation rates around ∼10 M /yr and sizes ranging from 0.2 to 0.5 kpc, which agrees well with previous observations and expectations for objects in the early Universe. The sample size and luminosity distribution are consistent with previous findings.

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Spectroscopy of z ∼ 7 candidate galaxies: using Lyman α to constrain the neutral fraction of hydrogen in the high-redshift universe★

Cited by 166 publications

References 53 publications

ALMA [C ii] 158 μm Detection of a Redshift 7 Lensed Galaxy behind RX J1347.1−1145*

ALMA [C ii] 158 μm Detection of a Redshift 7 Lensed Galaxy behind RX J1347.1−1145*

ARE ULTRA-FAINT GALAXIES ATz= 6–8 RESPONSIBLE FOR COSMIC REIONIZATION? COMBINED CONSTRAINTS FROM THE HUBBLE FRONTIER FIELDS CLUSTERS AND PARALLELS

Frontier Fields: Combining HST, VLT, andSpitzerdata to explore thez~ 8 Universe behind the lensing cluster MACSJ0416.1−2403

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