Gran Telescopio Canarias observations of an overdense region of Lyman α emitters at z = 6.5

Chanchaiworawit, K.; Guzmán, R.; Espinosa, J. M. Rodríguez; Castro-Rodríguez, N.; Salvador-Solé, E.; Calvi, Rosa; Gallego, J.; Herrero, A.; Manrique, Alberto; Marín-Franch, A.; Mas-Hesse, J. M.; Aretxaga, I.; Carrasco, E.; Terlevich, Elena; Terlevich, R.

doi:10.1093/mnras/stx782

Cited by 16 publications

(38 citation statements)

References 108 publications

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“…Here we define overdensities as regions whose overdensity significances are higher than 4σ levels. We identify overdensities previously reported in Higuchi et al (2018); z6PCC1, z6PCC3, and z6PCC4 at z = 5.7, and z7PCC24 and z7PCC26 (see also Chanchaiworawit et al 2017Chanchaiworawit et al , 2019 at z = 6.6. 1 z6PCC1 is the same structures reported in Ouchi et al (2005) and Jiang et al (2018, see Section 4.1).…”

Section: Lae Samplesupporting

confidence: 75%

SILVERRUSH. VIII. Spectroscopic Identifications of Early Large-scale Structures with Protoclusters over 200 Mpc at z ∼ 6–7: Strong Associations of Dusty Star-forming Galaxies

Harikane

Ouchi

Ono

et al. 2019

ApJ

105

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We have obtained three-dimensional maps of the universe in ∼ 200×200×80 comoving Mpc 3 (cMpc 3 ) volumes each at z = 5.7 and 6.6 based on a spectroscopic sample of 179 galaxies that achieves 80% completeness down to the Lyα luminosity of log(L Lyα /[erg s −1 ]) = 43.0, based on our Keck and Gemini observations and the literature. The maps reveal filamentary large-scale structures and two remarkable overdensities made out of at least 44 and 12 galaxies at z = 5.692 (z57OD) and z = 6.585 (z66OD), respectively, making z66OD the most distant overdensity spectroscopically confirmed to date with > 10 spectroscopically confirmed galaxies. We compare spatial distributions of submillimeter galaxies at z 4 − 6 with our z = 5.7 galaxies forming the large-scale structures, and detect a 99.97% signal of cross correlation, indicative of a clear coincidence of dusty star-forming galaxy and dust unobscured galaxy formation at this early epoch. The galaxies in z57OD and z66OD are actively forming stars with star formation rates (SFRs) 5 times higher than the main sequence, and particularly the SFR density in z57OD is 10 times higher than the cosmic average at the redshift (a.k.a. the Madau-Lilly plot). Comparisons with numerical simulations suggest that z57OD and z66OD are protoclusters that are progenitors of the present-day clusters with halo masses of ∼ 10 14 M .

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Section: Lae Samplesupporting

confidence: 75%

SILVERRUSH. VIII. Spectroscopic Identifications of Early Large-scale Structures with Protoclusters over 200 Mpc at z ∼ 6–7: Strong Associations of Dusty Star-forming Galaxies

Harikane

Ouchi

Ono

et al. 2019

ApJ

105

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“…Deriving the Lyα rest-frame equivalent widths of the LAEs could be just a simple task, if any continuum flux would have been detected. However, in our case, the UV continuum was not detected, beyond 2σ level, for any of the LAEs, not even in the photometric observations, except for 3 objects (Chanchaiworawit et al 2017). Thus, the only sound solution to estimate the rest-frame equivalent widths of the LAEs is to give lower limit values.…”

Section: Lyα Equivalent Widths and Escape Fractionscontrasting

confidence: 64%

“…We have confirmed 10 out of the 16 LAE candidates, which is a success rate of 62.5% or non detection rate of 37.2%. This percentage is slightly above 1 3 , which is the spuriousness rate previously determined in the photometry (Chanchaiworawit et al 2017).…”

Section: The Final Spectrasupporting

confidence: 48%

MOS spectroscopy of protocluster candidate galaxies at z = 6.5

Calvi

Espinosa

Más‐Hesse

et al. 2019

Monthly Notices of the Royal Astronomical Society

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The epoch corresponding to a redshift of z ∼ 6.5 is close to full re-ionisation of the Universe, and early enough to provide an intriguing environment to observe the early stage of large-scale structure formation. It is also en epoch that can be used to verify the abundance of a large population of low luminosity star-forming galaxies, that are deemed responsible for cosmic re-ionisation. Here, we present the results of follow-up multi-object spectroscopy using OSIRIS at Gran Telescopio Canarias (GTC) of 16 Lyα emitter (LAE) candidates discovered in the Subaru/XMM Newton Deep Survey. We have securely confirmed 10 LAEs with sufficient signal-to-noise ratio of the Lyα emission line. The inferred star formation rates of the confirmed LAEs are on the low side, within the range 0.9-4.7 M yr −1 . However, they show relatively high Lyα rest frame equivalent widths. Finally we have shown that the mechanical energy released by the star formation episodes in these galaxies is enough to create holes in the neutral hydrogen medium such that Lyman continuum photons can escape to the intergalactic medium, thus contributing to the re-ionisation of the Universe.

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“…We used a 0 ′′ .8 slit width that gives a spectral resolution of 1, 000 − 2, 000. We perform data reduction with the Carnegie Observatories System for MultiObject Spectroscopy (COSMOS) pipeline, and detect Lyα emission lines around 8160Å (9210Å ) for 130 (22) Ouchi et al 2010, and Hu et al 2016, we use the redshift catalogs for the spectroscopically confirmed LAEs at z = 5.7 (6.6) taken from Ouchi et al (2005), Ouchi et al (2008), Mallery et al (2012), Chanchaiworawit et al (2017), and Guzmán et al (in preparation). We make unified spectroscopic catalogs of LAEs at z = 5.7 and 6.6 Tables 4 and 5, respectively.…”

Section: Magellan/imacs Observationmentioning

confidence: 99%

SILVERRUSH. VII. Subaru/HSC Identifications of Protocluster Candidates at z ∼ 6–7: Implications for Cosmic Reionization

Higuchi

Ouchi

Ono

et al. 2019

ApJ

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We report fourteen and twenty-eight protocluster candidates at z = 5.7 and 6.6 over 14 and 19 deg 2 areas, respectively, selected from 2,230 (259) Lyα emitters (LAEs) photometrically (spectroscopically) identified with Subaru/Hyper Suprime-Cam (HSC) deep images (Keck, Subaru, and Magellan spectra and the literature data). Six out of the 42 protocluster candidates include 1 − 12 spectroscopically confirmed LAEs at redshifts up to z = 6.574. By the comparisons with the cosmological Lyα radiative transfer (RT) model reproducing LAEs with the reionization effects, we find that more than a half of these protocluster candidates are progenitors of the present-day clusters with a mass of 10 14 M ⊙ . We then investigate the correlation between LAE overdensity δ and Lyα rest-frame equivalent width EW rest Lyα , because the cosmological Lyα RT model suggests that a slope of EW rest Lyα -δ relation is steepened towards the epoch of cosmic reionization (EoR), due to the existence of the ionized bubbles around galaxy overdensities easing the escape of Lyα emission from the partly neutral intergalactic medium (IGM). The available HSC data suggest that the slope of the EW rest Lyα -δ correlation does not evolve from the post-reionization epoch z = 5.7 to the EoR z = 6.6 beyond the moderately large statistical errors. There is a possibility that we would detect the evolution of the EW rest Lyα -δ relation from z = 5.7 to 7.3 by the upcoming HSC observations providing large samples of LAEs at z = 6.6 − 7.3.

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Gran Telescopio Canarias observations of an overdense region of Lyman α emitters at z = 6.5

Cited by 16 publications

References 108 publications

SILVERRUSH. VIII. Spectroscopic Identifications of Early Large-scale Structures with Protoclusters over 200 Mpc at z ∼ 6–7: Strong Associations of Dusty Star-forming Galaxies

SILVERRUSH. VIII. Spectroscopic Identifications of Early Large-scale Structures with Protoclusters over 200 Mpc at z ∼ 6–7: Strong Associations of Dusty Star-forming Galaxies

MOS spectroscopy of protocluster candidate galaxies at z = 6.5

SILVERRUSH. VII. Subaru/HSC Identifications of Protocluster Candidates at z ∼ 6–7: Implications for Cosmic Reionization

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