---
_id: '11558'
abstract:
- lang: eng
text: We present and explore deep narrow- and medium-band data obtained with the
Subaru and the Isaac Newton Telescopes in the ∼2 deg2 COSMOS field. We use these
data as an extremely wide, low-resolution (R ∼ 20–80) Integral Field Unit survey
to slice through the COSMOS field and obtain a large sample of ∼4000 Ly α emitters
(LAEs) from z ∼ 2 to 6 in 16 redshift slices (SC4K). We present new Ly α luminosity
functions (LFs) covering a comoving volume of ∼108 Mpc3. SC4K extensively complements
ultradeep surveys, jointly covering over 4 dex in Ly α luminosity and revealing
a global (2.5 < z < 6) synergy LF with α=−1.93+0.12−0.12, log10Φ∗Lyα=−3.45+0.22−0.29 Mpc−3,
and log10L∗Lyα=42.93+0.15−0.11 erg s−1. The Schechter component of the Ly α LF
reveals a factor ∼5 rise in L∗Lyα and a ∼7 × decline in Φ∗Lyα from z ∼ 2 to 6.
The data reveal an extra power-law (or Schechter) component above LLy α ≈ 1043.3 erg s−1
at z ∼ 2.2–3.5 and we show that it is partially driven by X-ray and radio active
galactic nucleus (AGN), as their Ly α LF resembles the excess. The power-law component
vanishes and/or is below our detection limits above z > 3.5, likely linked with
the evolution of the AGN population. The Ly α luminosity density rises by a factor
∼2 from z ∼ 2 to 3 but is then found to be roughly constant (1.1+0.2−0.2×1040 erg s−1 Mpc−3)
to z ∼ 6, despite the ∼0.7 dex drop in ultraviolet (UV) luminosity density. The
Ly α/UV luminosity density ratio rises from 4 ± 1 per cent to 30 ± 6 per cent
from z ∼ 2.2 to 6. Our results imply a rise of a factor of ≈2 in the global ionization
efficiency (ξion) and a factor ≈4 ± 1 in the Ly α escape fraction from z ∼ 2 to
6, hinting for evolution in both the typical burstiness/stellar populations and
even more so in the typical interstellar medium conditions allowing Ly α photons
to escape.
acknowledgement: "We thank the anonymous referee for their constructive comments that
helped us improve the manuscript. DS acknowledges the hospitality of the IAC and
a Severo Ochoa visiting grant. SS and JC acknowledge studentships from the Lancaster
University. JM acknowledges a Huygens PhD fellowship from Leiden University. APA
acknowledges financial support from the Science and Technology Foundation (FCT,
Portugal) through research grants UID/FIS/04434/2013 and fellowship PD/BD/52706/2014.
The authors thank Alyssa Drake, Kimihiko Nakajima, Yuichi Harikane, Max Gronke,
Irene Shivaei, Helmut Dannerbauer, Huub Rottgering, ¨ Marius Eide, and Masami Ouchi
for many engaging and stimulating discussions. We also thank Sara Perez, Alex Bennett,
and Tom Rose for their involvement in the early stages of this project. Based on
data products from observations made with European Southern Observatory (ESO) Telescopes
at the La Silla Paranal Observatory under ESO programme IDs 294.A-5018, 097.A 0943,\r\n098.A-0819,
099.A-0254, and 179.A-2005 and on data products produced by TERAPIX and the Cambridge
Astronomy Survey Unit on behalf of the UltraVISTA consortium. Based on observations
using the WFC on the 2.5 m INT, as part of programmes 2013AN002, 2013BN008, 2014AC88,
2014AN002, 2014BN006, 2014BC118, and 2016AN001. The INT is 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. 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 (CFHTLS), a collaborative
project of NRC and CNRS.\r\nWe are grateful to the CFHTLS, COSMOS-UltraVISTA, and
COSMOS survey teams. We are also unmeasurably thankful to the pioneering and continuous
work from previous Ly α surveys’ teams. Without these previous Ly α and the wider
reach legacy surveys, this research would have been impossible. We also thank the
VUDS team for making available spectroscopic redshifts from data obtained with VIMOS
at the European Southern Observatory Very Large Telescope, Paranal, Chile, under
Large Programme 185.A-0791. Finally, the authors acknowledge the unique value of
the publicly available programming language PYTHON, including the NUMPY and SCIPY
(Van Der Walt, Colbert & Varoquaux 2011; Jones et al. 2001), MATPLOTLIB (Hunter
2007), ASTROPY (Astropy Collaboration et al. 2013), and the TOPCAT analysis program
(Taylor 2005). We publicly release a catalogue with all LAEs used in this paper
(SC4K), so it can be freely explored by the community (see five example entries
in Table A1)."
article_processing_charge: No
article_type: original
arxiv: 1
author:
- first_name: David
full_name: Sobral, David
last_name: Sobral
- first_name: Sérgio
full_name: Santos, Sérgio
last_name: Santos
- 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: Ana
full_name: Paulino-Afonso, Ana
last_name: Paulino-Afonso
- first_name: Bruno
full_name: Ribeiro, Bruno
last_name: Ribeiro
- first_name: João
full_name: Calhau, João
last_name: Calhau
- first_name: Ali A
full_name: Khostovan, Ali A
last_name: Khostovan
citation:
ama: 'Sobral D, Santos S, Matthee JJ, et al. Slicing COSMOS with SC4K: The evolution
of typical Ly α emitters and the Ly α escape fraction from z ∼ 2 to 6. Monthly
Notices of the Royal Astronomical Society. 2018;476(4):4725-4752. doi:10.1093/mnras/sty378'
apa: 'Sobral, D., Santos, S., Matthee, J. J., Paulino-Afonso, A., Ribeiro, B., Calhau,
J., & Khostovan, A. A. (2018). Slicing COSMOS with SC4K: The evolution of
typical Ly α emitters and the Ly α escape fraction from z ∼ 2 to 6. Monthly
Notices of the Royal Astronomical Society. Oxford University Press. https://doi.org/10.1093/mnras/sty378'
chicago: 'Sobral, David, Sérgio Santos, Jorryt J Matthee, Ana Paulino-Afonso, Bruno
Ribeiro, João Calhau, and Ali A Khostovan. “Slicing COSMOS with SC4K: The Evolution
of Typical Ly α Emitters and the Ly α Escape Fraction from z ∼ 2 to 6.” Monthly
Notices of the Royal Astronomical Society. Oxford University Press, 2018.
https://doi.org/10.1093/mnras/sty378.'
ieee: 'D. Sobral et al., “Slicing COSMOS with SC4K: The evolution of typical
Ly α emitters and the Ly α escape fraction from z ∼ 2 to 6,” Monthly Notices
of the Royal Astronomical Society, vol. 476, no. 4. Oxford University Press,
pp. 4725–4752, 2018.'
ista: 'Sobral D, Santos S, Matthee JJ, Paulino-Afonso A, Ribeiro B, Calhau J, Khostovan
AA. 2018. Slicing COSMOS with SC4K: The evolution of typical Ly α emitters and
the Ly α escape fraction from z ∼ 2 to 6. Monthly Notices of the Royal Astronomical
Society. 476(4), 4725–4752.'
mla: 'Sobral, David, et al. “Slicing COSMOS with SC4K: The Evolution of Typical
Ly α Emitters and the Ly α Escape Fraction from z ∼ 2 to 6.” Monthly Notices
of the Royal Astronomical Society, vol. 476, no. 4, Oxford University Press,
2018, pp. 4725–52, doi:10.1093/mnras/sty378.'
short: D. Sobral, S. Santos, J.J. Matthee, A. Paulino-Afonso, B. Ribeiro, J. Calhau,
A.A. Khostovan, Monthly Notices of the Royal Astronomical Society 476 (2018) 4725–4752.
date_created: 2022-07-12T10:41:08Z
date_published: 2018-06-01T00:00:00Z
date_updated: 2022-08-19T07:04:45Z
day: '01'
doi: 10.1093/mnras/sty378
extern: '1'
external_id:
arxiv:
- '1712.04451'
intvolume: ' 476'
issue: '4'
keyword:
- Space and Planetary Science
- Astronomy and Astrophysics
- 'galaxies: evolution'
- 'galaxies: formation'
- 'galaxies: high-redshift'
- 'galaxies: luminosity function'
- mass function
- 'galaxies: statistics'
language:
- iso: eng
main_file_link:
- open_access: '1'
url: https://arxiv.org/abs/1712.04451
month: '06'
oa: 1
oa_version: Preprint
page: 4725-4752
publication: Monthly Notices of the Royal Astronomical Society
publication_identifier:
eissn:
- 1365-2966
issn:
- 0035-8711
publication_status: published
publisher: Oxford University Press
quality_controlled: '1'
scopus_import: '1'
status: public
title: 'Slicing COSMOS with SC4K: The evolution of typical Ly α emitters and the Ly α
escape fraction from z ∼ 2 to 6'
type: journal_article
user_id: 2DF688A6-F248-11E8-B48F-1D18A9856A87
volume: 476
year: '2018'
...