Spectroscopic detections of C III] λ1909 Å at z ≃ 6-7: A new probe of early star-forming galaxies and cosmic reionization

Daniel P Stark, Johan Richard, Stéphane Charlot, Benjamin Clément, Richard Ellis, Brian Siana, Brant E Robertson, Matthew Schenker, Julia Gutkin, Aida Wofford

Research output: Contribution to journalArticle

92 Citations (Scopus)

Abstract

Deep spectroscopic observations of z ≳ 6.5 galaxies have revealed a marked decline with increasing redshift in the detectability of Ly α emission. While this may offer valuable insight into the end of the reionization process, it presents a challenge to the detailed spectroscopic study of bright photometrically-selected distant sources now being found via deep Hubble Space Telescope imaging, and particularly those highly magnified sources viewed through foreground lensing clusters. In this paper,we demonstrate the validity of a newway forward via the detection of an alternative diagnostic line, CIII] λ1909 Å, seen in spectroscopic exposures of a star-forming galaxy at z<inf>Lyα</inf> = 6.029. We also report tentative detection of CIII] λ1909 Å in a galaxy at z<inf>Lyα</inf> = 7.213. The former 3.3σ detection is based on a 3.5 h XShooter spectrum of a bright (J<inf>125</inf> = 25.2) gravitationally-lensed galaxy behind the cluster Abell 383. The latter 2.8σ detection is based on a 4.2 h MOSFIRE spectra of one of the most distant spectroscopically confirmed galaxies, GN-108036, with J<inf>140</inf> = 25.2. Both targets were chosen for their continuum brightness and previously-known redshift (based on Ly α), ensuring that any C III] emission would be located in a favourable portion of the near-infrared sky spectrum. Since the availability of secure Ly α redshifts significantly narrows the wavelength range where CIII] is sought, this increases confidence in these, otherwise, low-signal-to-noise ratio detections. We compare our CIII] and Ly α equivalent widths in the context of those found at z ≃ 2 from earlier work and discuss the motivation for using lines other than Ly α to study galaxies in the reionization era.

Original languageEnglish (US)
Pages (from-to)1846-1855
Number of pages10
JournalMonthly Notices of the Royal Astronomical Society
Volume450
Issue number2
DOIs
StatePublished - Apr 10 2015

Fingerprint

early stars
probe
galaxies
probes
signal-to-noise ratio
near infrared
Hubble Space Telescope
availability
sky
detection
confidence
brightness
wavelength
signal to noise ratios
continuums
stars
wavelengths

Keywords

  • Cosmology: observations
  • Galaxies: evolution
  • Galaxies: formation
  • Galaxies: high-redshift

ASJC Scopus subject areas

  • Space and Planetary Science
  • Astronomy and Astrophysics

Cite this

Spectroscopic detections of C III] λ1909 Å at z ≃ 6-7 : A new probe of early star-forming galaxies and cosmic reionization. / Stark, Daniel P; Richard, Johan; Charlot, Stéphane; Clément, Benjamin; Ellis, Richard; Siana, Brian; Robertson, Brant E; Schenker, Matthew; Gutkin, Julia; Wofford, Aida.

In: Monthly Notices of the Royal Astronomical Society, Vol. 450, No. 2, 10.04.2015, p. 1846-1855.

Research output: Contribution to journalArticle

Stark, Daniel P ; Richard, Johan ; Charlot, Stéphane ; Clément, Benjamin ; Ellis, Richard ; Siana, Brian ; Robertson, Brant E ; Schenker, Matthew ; Gutkin, Julia ; Wofford, Aida. / Spectroscopic detections of C III] λ1909 Å at z ≃ 6-7 : A new probe of early star-forming galaxies and cosmic reionization. In: Monthly Notices of the Royal Astronomical Society. 2015 ; Vol. 450, No. 2. pp. 1846-1855.
@article{f765db000a2a46488db073ba88c5af91,
title = "Spectroscopic detections of C III] λ1909 {\AA} at z ≃ 6-7: A new probe of early star-forming galaxies and cosmic reionization",
abstract = "Deep spectroscopic observations of z ≳ 6.5 galaxies have revealed a marked decline with increasing redshift in the detectability of Ly α emission. While this may offer valuable insight into the end of the reionization process, it presents a challenge to the detailed spectroscopic study of bright photometrically-selected distant sources now being found via deep Hubble Space Telescope imaging, and particularly those highly magnified sources viewed through foreground lensing clusters. In this paper,we demonstrate the validity of a newway forward via the detection of an alternative diagnostic line, CIII] λ1909 {\AA}, seen in spectroscopic exposures of a star-forming galaxy at zLyα = 6.029. We also report tentative detection of CIII] λ1909 {\AA} in a galaxy at zLyα = 7.213. The former 3.3σ detection is based on a 3.5 h XShooter spectrum of a bright (J125 = 25.2) gravitationally-lensed galaxy behind the cluster Abell 383. The latter 2.8σ detection is based on a 4.2 h MOSFIRE spectra of one of the most distant spectroscopically confirmed galaxies, GN-108036, with J140 = 25.2. Both targets were chosen for their continuum brightness and previously-known redshift (based on Ly α), ensuring that any C III] emission would be located in a favourable portion of the near-infrared sky spectrum. Since the availability of secure Ly α redshifts significantly narrows the wavelength range where CIII] is sought, this increases confidence in these, otherwise, low-signal-to-noise ratio detections. We compare our CIII] and Ly α equivalent widths in the context of those found at z ≃ 2 from earlier work and discuss the motivation for using lines other than Ly α to study galaxies in the reionization era.",
keywords = "Cosmology: observations, Galaxies: evolution, Galaxies: formation, Galaxies: high-redshift",
author = "Stark, {Daniel P} and Johan Richard and St{\'e}phane Charlot and Benjamin Cl{\'e}ment and Richard Ellis and Brian Siana and Robertson, {Brant E} and Matthew Schenker and Julia Gutkin and Aida Wofford",
year = "2015",
month = "4",
day = "10",
doi = "10.1093/mnras/stv688",
language = "English (US)",
volume = "450",
pages = "1846--1855",
journal = "Monthly Notices of the Royal Astronomical Society",
issn = "0035-8711",
publisher = "Oxford University Press",
number = "2",

}

TY - JOUR

T1 - Spectroscopic detections of C III] λ1909 Å at z ≃ 6-7

T2 - A new probe of early star-forming galaxies and cosmic reionization

AU - Stark, Daniel P

AU - Richard, Johan

AU - Charlot, Stéphane

AU - Clément, Benjamin

AU - Ellis, Richard

AU - Siana, Brian

AU - Robertson, Brant E

AU - Schenker, Matthew

AU - Gutkin, Julia

AU - Wofford, Aida

PY - 2015/4/10

Y1 - 2015/4/10

N2 - Deep spectroscopic observations of z ≳ 6.5 galaxies have revealed a marked decline with increasing redshift in the detectability of Ly α emission. While this may offer valuable insight into the end of the reionization process, it presents a challenge to the detailed spectroscopic study of bright photometrically-selected distant sources now being found via deep Hubble Space Telescope imaging, and particularly those highly magnified sources viewed through foreground lensing clusters. In this paper,we demonstrate the validity of a newway forward via the detection of an alternative diagnostic line, CIII] λ1909 Å, seen in spectroscopic exposures of a star-forming galaxy at zLyα = 6.029. We also report tentative detection of CIII] λ1909 Å in a galaxy at zLyα = 7.213. The former 3.3σ detection is based on a 3.5 h XShooter spectrum of a bright (J125 = 25.2) gravitationally-lensed galaxy behind the cluster Abell 383. The latter 2.8σ detection is based on a 4.2 h MOSFIRE spectra of one of the most distant spectroscopically confirmed galaxies, GN-108036, with J140 = 25.2. Both targets were chosen for their continuum brightness and previously-known redshift (based on Ly α), ensuring that any C III] emission would be located in a favourable portion of the near-infrared sky spectrum. Since the availability of secure Ly α redshifts significantly narrows the wavelength range where CIII] is sought, this increases confidence in these, otherwise, low-signal-to-noise ratio detections. We compare our CIII] and Ly α equivalent widths in the context of those found at z ≃ 2 from earlier work and discuss the motivation for using lines other than Ly α to study galaxies in the reionization era.

AB - Deep spectroscopic observations of z ≳ 6.5 galaxies have revealed a marked decline with increasing redshift in the detectability of Ly α emission. While this may offer valuable insight into the end of the reionization process, it presents a challenge to the detailed spectroscopic study of bright photometrically-selected distant sources now being found via deep Hubble Space Telescope imaging, and particularly those highly magnified sources viewed through foreground lensing clusters. In this paper,we demonstrate the validity of a newway forward via the detection of an alternative diagnostic line, CIII] λ1909 Å, seen in spectroscopic exposures of a star-forming galaxy at zLyα = 6.029. We also report tentative detection of CIII] λ1909 Å in a galaxy at zLyα = 7.213. The former 3.3σ detection is based on a 3.5 h XShooter spectrum of a bright (J125 = 25.2) gravitationally-lensed galaxy behind the cluster Abell 383. The latter 2.8σ detection is based on a 4.2 h MOSFIRE spectra of one of the most distant spectroscopically confirmed galaxies, GN-108036, with J140 = 25.2. Both targets were chosen for their continuum brightness and previously-known redshift (based on Ly α), ensuring that any C III] emission would be located in a favourable portion of the near-infrared sky spectrum. Since the availability of secure Ly α redshifts significantly narrows the wavelength range where CIII] is sought, this increases confidence in these, otherwise, low-signal-to-noise ratio detections. We compare our CIII] and Ly α equivalent widths in the context of those found at z ≃ 2 from earlier work and discuss the motivation for using lines other than Ly α to study galaxies in the reionization era.

KW - Cosmology: observations

KW - Galaxies: evolution

KW - Galaxies: formation

KW - Galaxies: high-redshift

UR - http://www.scopus.com/inward/record.url?scp=84929638221&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84929638221&partnerID=8YFLogxK

U2 - 10.1093/mnras/stv688

DO - 10.1093/mnras/stv688

M3 - Article

AN - SCOPUS:84929638221

VL - 450

SP - 1846

EP - 1855

JO - Monthly Notices of the Royal Astronomical Society

JF - Monthly Notices of the Royal Astronomical Society

SN - 0035-8711

IS - 2

ER -