---
_id: '11519'
abstract:
- lang: eng
text: 'Faint Lyα emitters become increasingly rarer toward the reionization epoch
(z ∼ 6–7). However, observations from a very large (∼5 deg2) Lyα narrow-band survey
at z = 6.6 show that this is not the case for the most luminous emitters, capable
of ionizing their own local bubbles. Here we present follow-up observations of
the two most luminous Lyα candidates in the COSMOS field: “MASOSA” and “CR7.”
We used X-SHOOTER, SINFONI, and FORS2 on the Very Large Telescope, and DEIMOS
on Keck, to confirm both candidates beyond any doubt. We find redshifts of z =
6.541 and z = 6.604 for “MASOSA” and “CR7,” respectively. MASOSA has a strong
detection in Lyα with a line width of 386 ± 30 km s−1 (FWHM) and with very high
EW0 (>200 Å), but undetected in the continuum, implying very low stellar mass
and a likely young, metal-poor stellar population. “CR7,” with an observed Lyα
luminosity of 1043.92±0.05 erg s−1 is the most luminous Lyα emitter ever found
at z > 6 and is spatially extended (∼16 kpc). “CR7” reveals a narrow Lyα line
with 266 ± 15 km s−1 FWHM, being detected in the near-infrared (NIR) (rest-frame
UV; β = −2.3 ± 0.1) and in IRAC/Spitzer. We detect a narrow He II 1640 Å emission
line (6σ, FWHM = 130 ± 30 km s−1 ) in CR7 which can explain the clear excess seen
in the J-band photometry (EW0 ∼ 80 Å). We find no other emission lines from the
UV to the NIR in our X-SHOOTER spectra (He II/O III] 1663 Å > 3 and He II/C III]
1908 Å > 2.5). We conclude that CR7 is best explained by a combination of a PopIII-like
population, which dominates the rest-frame UV and the nebular emission, and a
more normal stellar population, which presumably dominates the mass. Hubble Space
Telescope/WFC3 observations show that the light is indeed spatially separated
between a very blue component, coincident with Lyα and He II emission, and two
red components (∼5 kpc away), which dominate the mass. Our findings are consistent
with theoretical predictions of a PopIII wave, with PopIII star formation migrating
away from the original sites of star formation.'
acknowledgement: We thank the anonymous reviewer for useful and constructive comments
and suggestions which greatly improved the quality and clarity of our work. D.S.
acknowledges financial support from the Netherlands Organisation for Scientific
research (NWO) through a Veni fellowship, from FCT through a FCT Investigator Starting
Grant and Start-up Grant (IF/01154/2012/CP0189/CT0010), from FCT grant UID/FIS/04434/2013,
and from LSF and LKBF. J.M. acknowledges the award of a Huygens PhD fellowship.
H.R. acknowledges support from the ERC Advanced Investigator program NewClusters
321271. The authors thank Mark Dijkstra, Bhaskar Agarwal, Jarrett Johnson, Andrea
Ferrara, Jarle Brinchmann, Rebecca Bowler, George Becker, Emma Curtis-Lake, Milos
Milosavljevic, Raffaella Schneider, Paul Shapiro, and Erik Zackrisson for interesting,
stimulating and helpful discussions. The authors are extremely grateful to ESO for
the award of ESO DDT time (294.A-5018 and 294.A-5039) which allowed the spectroscopic
confirmation of both sources and the detailed investigation of their nature. Observations
are also based on data from W.M. Keck Observatory. The W.M. Keck Observatory is
operated as a scientific partnership of Caltech, the University of California and
the National Aeronautics and Space Administration. Based on observations obtained
with MegaPrime/Megacam, a joint project of CFHT and CEA/IRFU, at the Canada–France–Hawaii
Telescope (CFHT) which is operated by the National Research Council (NRC) of Canada,
the Institut National des Science de lUnivers of the Centre National de la Recherche
Scientifique (CNRS) of France, and the University of Hawaii. This work is based
in part on data products produced at Terapix available at the Canadian Astronomy
Data Centre as part of the Canada–France–Hawaii Telescope Legacy Survey, a collaborative
project of NRC and CNRS. Based on data products from observations made with ESO
Telescopes at the La Silla Paranal Observatory under ESO programme IDs 294.A-5018,
294.A-5039, and 179.A-2005, and on data products produced by TERAPIX and the Cambridge
Astronomy Survey Unit on behalf of the UltraVISTA consortium. The authors acknowledge
the award of service time (SW2014b20) on the William Herschel Telescope (WHT). WHT
and its service programme are operated on the island of La Palma by the Isaac Newton
Group in the Spanish Observatorio del Roque de los Muchachos of the Instituto de
Astrofisica de Canarias.
article_processing_charge: No
article_type: original
arxiv: 1
author:
- first_name: David
full_name: Sobral, David
last_name: Sobral
- first_name: Jorryt J
full_name: Matthee, Jorryt J
id: 7439a258-f3c0-11ec-9501-9df22fe06720
last_name: Matthee
orcid: 0000-0003-2871-127X
- first_name: Behnam
full_name: Darvish, Behnam
last_name: Darvish
- first_name: Daniel
full_name: Schaerer, Daniel
last_name: Schaerer
- first_name: Bahram
full_name: Mobasher, Bahram
last_name: Mobasher
- first_name: Huub
full_name: Röttgering, Huub
last_name: Röttgering
- first_name: Sérgio
full_name: Santos, Sérgio
last_name: Santos
- first_name: Shoubaneh
full_name: Hemmati, Shoubaneh
last_name: Hemmati
citation:
ama: 'Sobral D, Matthee JJ, Darvish B, et al. Evidence for PopIII-like stellar populations
in the most luminous Lyα emitters at the epoch of reionisation: Spectroscopic
confirmation. The Astrophysical Journal. 2015;808(2):139. doi:10.1088/0004-637X/808/2/139'
apa: 'Sobral, D., Matthee, J. J., Darvish, B., Schaerer, D., Mobasher, B., Röttgering,
H., … Hemmati, S. (2015). Evidence for PopIII-like stellar populations in the
most luminous Lyα emitters at the epoch of reionisation: Spectroscopic confirmation.
The Astrophysical Journal. IOP Publishing. https://doi.org/10.1088/0004-637X/808/2/139'
chicago: 'Sobral, David, Jorryt J Matthee, Behnam Darvish, Daniel Schaerer, Bahram
Mobasher, Huub Röttgering, Sérgio Santos, and Shoubaneh Hemmati. “Evidence for
PopIII-like Stellar Populations in the Most Luminous Lyα Emitters at the Epoch
of Reionisation: Spectroscopic Confirmation.” The Astrophysical Journal.
IOP Publishing, 2015. https://doi.org/10.1088/0004-637X/808/2/139.'
ieee: 'D. Sobral et al., “Evidence for PopIII-like stellar populations in
the most luminous Lyα emitters at the epoch of reionisation: Spectroscopic confirmation,”
The Astrophysical Journal, vol. 808, no. 2. IOP Publishing, p. 139, 2015.'
ista: 'Sobral D, Matthee JJ, Darvish B, Schaerer D, Mobasher B, Röttgering H, Santos
S, Hemmati S. 2015. Evidence for PopIII-like stellar populations in the most luminous
Lyα emitters at the epoch of reionisation: Spectroscopic confirmation. The Astrophysical
Journal. 808(2), 139.'
mla: 'Sobral, David, et al. “Evidence for PopIII-like Stellar Populations in the
Most Luminous Lyα Emitters at the Epoch of Reionisation: Spectroscopic Confirmation.”
The Astrophysical Journal, vol. 808, no. 2, IOP Publishing, 2015, p. 139,
doi:10.1088/0004-637X/808/2/139.'
short: D. Sobral, J.J. Matthee, B. Darvish, D. Schaerer, B. Mobasher, H. Röttgering,
S. Santos, S. Hemmati, The Astrophysical Journal 808 (2015) 139.
date_created: 2022-07-07T09:00:58Z
date_published: 2015-07-28T00:00:00Z
date_updated: 2022-08-18T10:30:13Z
day: '28'
doi: 10.1088/0004-637X/808/2/139
extern: '1'
external_id:
arxiv:
- '1504.01734'
intvolume: ' 808'
issue: '2'
keyword:
- Space and Planetary Science
- Astronomy and Astrophysics
- dark ages
- reionization
- 'first stars – early universe – galaxies: evolution'
language:
- iso: eng
main_file_link:
- open_access: '1'
url: https://arxiv.org/abs/1504.01734
month: '07'
oa: 1
oa_version: Preprint
page: '139'
publication: The Astrophysical Journal
publication_identifier:
eissn:
- 1538-4357
issn:
- 0004-637X
publication_status: published
publisher: IOP Publishing
quality_controlled: '1'
scopus_import: '1'
status: public
title: 'Evidence for PopIII-like stellar populations in the most luminous Lyα emitters
at the epoch of reionisation: Spectroscopic confirmation'
type: journal_article
user_id: 2DF688A6-F248-11E8-B48F-1D18A9856A87
volume: 808
year: '2015'
...