Evidence of a fast evolution of the UV luminosity function beyond redshift 6 from a deep HAWK-I survey of the GOODS-S field

Castellano, M.; Fontana, A.; Boutsia, K.; Grazian, A.; Pentericci, L.; Bouwens, Rychard; Dickinson, Mark; Giavalisco, Mauro; Santini, P.; Cristiani, S.; Fiore, F.; Gallozzi, S.; Giallongo, E.; Maiolino, R.; Mannucci, F.; Menci, Nicola; Moorwood, A. F. M.; Nonino, M.; Paris, D.; Renzini, A.; Rosati, P.; Salimbeni, S.; Testa, V.; Vanzella, E.

doi:10.1051/0004-6361/200913300

Cited by 71 publications

(64 citation statements)

References 75 publications

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“…3), although the detection in the z 850 band excludes it as a genuine z ∼ 9 candidate. In addition, two of the five candidates detected in the Y-band (z1 and Y3) fulfil the rough selection defined by Ouchi et al (2009) for z ∼ 7 candidates, but they are not included when applying the selections proposed by Wilkins et al (2010) or Castellano et al (2010), namely z − Y > 1.2(1.0) and Y − J < 2.0. Our candidates are indeed slightly redder in Y − J, which is consistent with all our sources having photometric redshifts z > ∼ 7.5.…”

Section: Comparison With Previous Resultsmentioning

confidence: 99%

Optical dropout galaxies lensed by the cluster A2667

Laporte

Pelló

Schaerer

et al. 2011

A&A

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Context. We investigate the nature and the physical properties of ten z, Y, and J-dropout galaxies selected in the field of the lensing cluster A2667. Aims. This cluster is part of our project aimed at obtaining deep photometry at ∼0.8-2.5 microns with ESO/VLT HAWK-I and FORS2 on a representative sample of lensing clusters extracted from our multi-wavelength combined surveys with Spitzer, HST, and Herschel. The goal is to identify a sample of redshift z ∼ 7-10 candidates accessible to detailed spectroscopic studies. Methods. Our selection is performed using the usual dropout technique based on deep I, z, Y, J, H, and Ks-band images (AB ∼ 26-27, 3σ), targeting z 7.5 galaxy candidates. We also include IRAC data between 3.6 and 8 μm, and MIPS 24 μm when available. In this paper, we concentrate on the complete Y and J-dropout sample among the sources detected with a high signal-to-noise ratio in both H and Ks bands, as well as the bright z-dropout sources fulfilling the color and magnitude selection criteria adopted by Capak and collaborators. SED-fitting and photometric redshifts were used to constrain the nature and the properties of these candidates. Results. Ten photometric candidates are selected within the ∼7 × 7 HAWK-I field of view (∼33 arcmin 2 of effective area once corrected for contamination and lensing dilution at z ∼ 7-10). All of these are detected in H and Ks bands in addition to J and/or IRAC 3.6 μm/4.5 μm images, with H AB ranging from 23.4 to 25.2, and have modest magnification factors between 1.1 and 1.4. Although best-fit photometric redshifts are obtained at high-z for all these candidates, the contamination by low-z interlopers is expected to be in the range ∼50-75% based on previous studies, and on comparison with the blank-field WIRCAM Ultra-Deep Survey (WUDS). The same result is obtained when photometric redshifts are computed using a luminosity prior, allowing us to remove half of the original sample. Among the remaining galaxies, two additional sources could be identified as low-z interlopers based on a detection at 24 μm and the HST z 850 band. These low-z interlopers are not accurately described by current spectral templates given the large break, and cannot be easily identified based on broad-band photometry in the optical and near-IR domains alone. A good fit at z ∼ 1.7-3 is obtained when assuming a young stellar population together with a strong extinction. Given the estimated dust extinction and high SFRs, some of them could also be detected in the IR or sub-mm bands. Conclusions. After correction for contaminants, the observed number counts at z 7.5 seem to agree with expectations for an evolving LF, and be inconsistent with a constant LF since z ∼ 4. At least one and up to three candidates in this sample are expected to be genuine high-z sources, although spectroscopy is still needed to confirm this.

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Section: Comparison With Previous Resultsmentioning

confidence: 99%

Optical dropout galaxies lensed by the cluster A2667

Laporte

Pelló

Schaerer

et al. 2011

A&A

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“…1) as part of a Large ESO Programme (Prog-Id: 181.A-0485, PI: Cuby) and a HAWK-I science verification programme (Prog-Id: 60.A-9284(B), PI: Fontana). For details on the observations and data reduction we refer to Castellano et al (2010) and Clément et al (2012). The field is in the northern half of the GOODS-S field (centred at RA, Dec = 03 h 32 m 29 s , −27 d 44 m 42 s , J2000).…”

Section: Imaging Observationsmentioning

confidence: 99%

Emission-line-selected galaxies atz= 0.6–2 in GOODS South: Stellar masses, SFRs, and large-scale structure

Kochiashvili

Møller

Milvang-Jensen

et al. 2015

A&A

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We have obtained deep NIR narrow and broad (J and Y) band imaging data of the GOODS-South field. The narrow band filter is centered at 1060 nm corresponding to redshifts z = 0.62, 1.15, 1.85 for the strong emission lines Hα, [Oiii]/Hβ and [Oii], respectively. From those data we extract a well defined sample (M(AB) = 24.8 in the narrow band) of objects with large emission line equivalent widths in the narrow band. Via SED fits to published broad band data we identify which of the three lines we have detected and assign redshifts accordingly. This results in a well defined, strong emission line selected sample of galaxies down to lower masses than can easily be obtained with only continuum flux limited selection techniques. We compare the (SED fitting-derived) main sequence of star-formation (MS) of our sample to previous works and find that it has a steeper slope than that of samples of more massive galaxies. We conclude that the MS steepens at lower (below M = 10 9.4 M ) galaxy masses. We also show that the SFR at any redshift is higher in our sample. We attribute this to the targeted selection of galaxies with large emission line equivalent widths, and conclude that our sample forms the upper boundary of the MS. We briefly investigate and outline how samples with accurate redshifts down to those low stellar masses open a new window to study the formation of large scale structure in the early universe. In particular we report on the detection of a young galaxy cluster at z = 1.85 which features a central massive galaxy which is the candidate of an early stage cD galaxy, and we identify a likely filament mapped out by [Oiii] and Hβ emitting galaxies at z = 1.15.

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“…The last object is detected in the Y-band but does not satisfy criterion #3 above; interestingly, it is identified with reference G2 1408 as a z ∼ 7 object in Castellano et al (2010, and references therein). This object has been followed up in spectroscopy (Fontana et al 2010), yielding a tentative detection of the Lyα line at a redshift z = 6.97. This object therefore appears to be an LBG, caught by its strong UV continuum emission detected in the NB1060 filter.…”

Section: Goods-smentioning

confidence: 99%

“…SuprimeCam on the Subaru Telescope has revolutionized the field by enabling large samples of LAEs to be furnished at z = 5.7 and z = 6.5 (Ouchi et al 2010;Hu et al 2010, and references therein). The largest samples of LBGs have been recently assembled (Bouwens et al 2011) from HST observations after the successful installation of the Wide Field Camera3 (WFC3) in May 2009, but LBGs can also be found from the ground with 8-10 m telescopes equipped with efficient near infrared (NIR) cameras (Castellano et al 2010). Quasars at high-redshift are also found using the Lyman break technique in multi-colour datasets over very wide fields.…”

Section: Introductionmentioning

confidence: 99%

Evolution of the observed Lyαluminosity function fromz= 6.5 toz= 7.7: evidence for the epoch of reionization?

Clément¹,

Cuby²,

Courbin³

et al. 2012

A&A

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Aims. Lyα emitters (LAEs) can be detected out to very high redshifts during the epoch of reionization. The evolution of the LAE luminosity function with redshift is a direct probe of the Lyα transmission of the intergalactic medium (IGM), and therefore of the IGM neutral-hydrogen fraction. Measuring the Lyα luminosity function (LF) of Lyα emitters at redshift z = 7.7 therefore allows us to constrain the ionizing state of the Universe at this redshift. Methods. We observed three 7. ′ 5×7. ′ 5 fields with the HAWK-I instrument at the VLT with a narrow band filter centred at 1.06 µm and targeting Lyα emitters at redshift z ∼ 7.7. The fields were chosen for the availability of multiwavelength data. One field is a galaxy cluster, the Bullet Cluster, which allowed us to use gravitational amplification to probe luminosities that are fainter than in the field. The two other fields are subareas of the GOODS Chandra Deep Field South and CFHTLS-D4 deep field. We selected z = 7.7 LAE candidates from a variety of colour criteria, in particular from the absence of detection in the optical bands. Results. We do not find any LAE candidates at z = 7.7 in ∼ 2.4 × 10 4 Mpc 3 down to a narrow band AB magnitude of ∼ 26, which allows us to infer robust constraints on the Lyα LAE luminosity function at this redshift. Conclusions. The predicted mean number of objects at z = 6.5, derived from somewhat different luminosity functions of Hu et al. (2010), Ouchi et al. (2010), and Kashikawa et al. (2011. Depending on which of these luminosity functions we refer to, we exclude a scenario with no evolution from z = 6.5 to z = 7.7 at 85% confidence without requiring a strong change in the IGM Lyα transmission, or at 99% confidence with a significant quenching of the IGM Lyα transmission, possibly from a strong increase in the high neutral-hydrogen fraction between these two redshifts.

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Evidence of a fast evolution of the UV luminosity function beyond redshift 6 from a deep HAWK-I survey of the GOODS-S field

Cited by 71 publications

References 75 publications

Optical dropout galaxies lensed by the cluster A2667

Optical dropout galaxies lensed by the cluster A2667

Emission-line-selected galaxies atz= 0.6–2 in GOODS South: Stellar masses, SFRs, and large-scale structure

Evolution of the observed Lyαluminosity function fromz= 6.5 toz= 7.7: evidence for the epoch of reionization?

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