Spectroscopic properties of the z ≈ 4.5 Lyα emitters

Steve Dawson, James E. Rhoads, Sangeeta Malhotra, Daniel Stern, Arjun Dey, Hyron Spinrad, Buell Tomasson Jannuzi, Junxian Wang, Emily Landes

Research output: Contribution to journalArticle

111 Citations (Scopus)

Abstract

We present Keck Low Resolution Imaging Spectrometer optical spectra of 17 Lyα-emitting galaxies and one Lyman break galaxy at z ≈ 4.5 discovered in the Large Area Lyman Alpha survey. The survey has identified a sample of ∼350 candidate Lyα-emitting galaxies at z ≈ 4.5 in a search volume of 1.5 × 106 comoving Mpc3. We targeted 25 candidates for spectroscopy; hence, the 18 confirmations presented herein suggest a selection reliability of 72%. The large equivalent widths (median Wλrest ≈ 80 Å) but narrow physical widths (Δv < 500 km s-1) of the Lyα emission lines, along with the lack of accompanying high-ionization state emission lines, suggest that these galaxies are young systems powered by star formation rather than by active galactic nucleus activity. Theoretical models of galaxy formation in the primordial universe suggest that a small fraction of Lyα-emitting galaxies at z ≈ 4.5 may still be nascent, metal-free objects. Indeed, we find with 90% confidence that three to five of the confirmed sources show W λrest > 240 Å, exceeding the maximum Lyα equivalent width predicted for normal stellar populations. Nonetheless, we find no evidence for He II λ1640 emission in either individual or composite spectra, indicating that although these galaxies are young, they are not truly primitive, Population III objects.

Original languageEnglish (US)
Pages (from-to)707-717
Number of pages11
JournalAstrophysical Journal
Volume617
Issue number2 I
DOIs
StatePublished - Dec 20 2004
Externally publishedYes

Fingerprint

emitters
galaxies
spectrometer
spectroscopy
imaging spectrometers
optical spectrum
composite materials
young

Keywords

  • Galaxies: evolution
  • Galaxies: high-redshift

ASJC Scopus subject areas

  • Space and Planetary Science

Cite this

Dawson, S., Rhoads, J. E., Malhotra, S., Stern, D., Dey, A., Spinrad, H., ... Landes, E. (2004). Spectroscopic properties of the z ≈ 4.5 Lyα emitters. Astrophysical Journal, 617(2 I), 707-717. https://doi.org/10.1086/425572

Spectroscopic properties of the z ≈ 4.5 Lyα emitters. / Dawson, Steve; Rhoads, James E.; Malhotra, Sangeeta; Stern, Daniel; Dey, Arjun; Spinrad, Hyron; Jannuzi, Buell Tomasson; Wang, Junxian; Landes, Emily.

In: Astrophysical Journal, Vol. 617, No. 2 I, 20.12.2004, p. 707-717.

Research output: Contribution to journalArticle

Dawson, S, Rhoads, JE, Malhotra, S, Stern, D, Dey, A, Spinrad, H, Jannuzi, BT, Wang, J & Landes, E 2004, 'Spectroscopic properties of the z ≈ 4.5 Lyα emitters', Astrophysical Journal, vol. 617, no. 2 I, pp. 707-717. https://doi.org/10.1086/425572
Dawson S, Rhoads JE, Malhotra S, Stern D, Dey A, Spinrad H et al. Spectroscopic properties of the z ≈ 4.5 Lyα emitters. Astrophysical Journal. 2004 Dec 20;617(2 I):707-717. https://doi.org/10.1086/425572
Dawson, Steve ; Rhoads, James E. ; Malhotra, Sangeeta ; Stern, Daniel ; Dey, Arjun ; Spinrad, Hyron ; Jannuzi, Buell Tomasson ; Wang, Junxian ; Landes, Emily. / Spectroscopic properties of the z ≈ 4.5 Lyα emitters. In: Astrophysical Journal. 2004 ; Vol. 617, No. 2 I. pp. 707-717.
@article{8a79d3e0f0f14a3baba87722d75d9777,
title = "Spectroscopic properties of the z ≈ 4.5 Lyα emitters",
abstract = "We present Keck Low Resolution Imaging Spectrometer optical spectra of 17 Lyα-emitting galaxies and one Lyman break galaxy at z ≈ 4.5 discovered in the Large Area Lyman Alpha survey. The survey has identified a sample of ∼350 candidate Lyα-emitting galaxies at z ≈ 4.5 in a search volume of 1.5 × 106 comoving Mpc3. We targeted 25 candidates for spectroscopy; hence, the 18 confirmations presented herein suggest a selection reliability of 72{\%}. The large equivalent widths (median Wλrest ≈ 80 {\AA}) but narrow physical widths (Δv < 500 km s-1) of the Lyα emission lines, along with the lack of accompanying high-ionization state emission lines, suggest that these galaxies are young systems powered by star formation rather than by active galactic nucleus activity. Theoretical models of galaxy formation in the primordial universe suggest that a small fraction of Lyα-emitting galaxies at z ≈ 4.5 may still be nascent, metal-free objects. Indeed, we find with 90{\%} confidence that three to five of the confirmed sources show W λrest > 240 {\AA}, exceeding the maximum Lyα equivalent width predicted for normal stellar populations. Nonetheless, we find no evidence for He II λ1640 emission in either individual or composite spectra, indicating that although these galaxies are young, they are not truly primitive, Population III objects.",
keywords = "Galaxies: evolution, Galaxies: high-redshift",
author = "Steve Dawson and Rhoads, {James E.} and Sangeeta Malhotra and Daniel Stern and Arjun Dey and Hyron Spinrad and Jannuzi, {Buell Tomasson} and Junxian Wang and Emily Landes",
year = "2004",
month = "12",
day = "20",
doi = "10.1086/425572",
language = "English (US)",
volume = "617",
pages = "707--717",
journal = "Astrophysical Journal",
issn = "0004-637X",
publisher = "IOP Publishing Ltd.",
number = "2 I",

}

TY - JOUR

T1 - Spectroscopic properties of the z ≈ 4.5 Lyα emitters

AU - Dawson, Steve

AU - Rhoads, James E.

AU - Malhotra, Sangeeta

AU - Stern, Daniel

AU - Dey, Arjun

AU - Spinrad, Hyron

AU - Jannuzi, Buell Tomasson

AU - Wang, Junxian

AU - Landes, Emily

PY - 2004/12/20

Y1 - 2004/12/20

N2 - We present Keck Low Resolution Imaging Spectrometer optical spectra of 17 Lyα-emitting galaxies and one Lyman break galaxy at z ≈ 4.5 discovered in the Large Area Lyman Alpha survey. The survey has identified a sample of ∼350 candidate Lyα-emitting galaxies at z ≈ 4.5 in a search volume of 1.5 × 106 comoving Mpc3. We targeted 25 candidates for spectroscopy; hence, the 18 confirmations presented herein suggest a selection reliability of 72%. The large equivalent widths (median Wλrest ≈ 80 Å) but narrow physical widths (Δv < 500 km s-1) of the Lyα emission lines, along with the lack of accompanying high-ionization state emission lines, suggest that these galaxies are young systems powered by star formation rather than by active galactic nucleus activity. Theoretical models of galaxy formation in the primordial universe suggest that a small fraction of Lyα-emitting galaxies at z ≈ 4.5 may still be nascent, metal-free objects. Indeed, we find with 90% confidence that three to five of the confirmed sources show W λrest > 240 Å, exceeding the maximum Lyα equivalent width predicted for normal stellar populations. Nonetheless, we find no evidence for He II λ1640 emission in either individual or composite spectra, indicating that although these galaxies are young, they are not truly primitive, Population III objects.

AB - We present Keck Low Resolution Imaging Spectrometer optical spectra of 17 Lyα-emitting galaxies and one Lyman break galaxy at z ≈ 4.5 discovered in the Large Area Lyman Alpha survey. The survey has identified a sample of ∼350 candidate Lyα-emitting galaxies at z ≈ 4.5 in a search volume of 1.5 × 106 comoving Mpc3. We targeted 25 candidates for spectroscopy; hence, the 18 confirmations presented herein suggest a selection reliability of 72%. The large equivalent widths (median Wλrest ≈ 80 Å) but narrow physical widths (Δv < 500 km s-1) of the Lyα emission lines, along with the lack of accompanying high-ionization state emission lines, suggest that these galaxies are young systems powered by star formation rather than by active galactic nucleus activity. Theoretical models of galaxy formation in the primordial universe suggest that a small fraction of Lyα-emitting galaxies at z ≈ 4.5 may still be nascent, metal-free objects. Indeed, we find with 90% confidence that three to five of the confirmed sources show W λrest > 240 Å, exceeding the maximum Lyα equivalent width predicted for normal stellar populations. Nonetheless, we find no evidence for He II λ1640 emission in either individual or composite spectra, indicating that although these galaxies are young, they are not truly primitive, Population III objects.

KW - Galaxies: evolution

KW - Galaxies: high-redshift

UR - http://www.scopus.com/inward/record.url?scp=13944271075&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=13944271075&partnerID=8YFLogxK

U2 - 10.1086/425572

DO - 10.1086/425572

M3 - Article

AN - SCOPUS:13944271075

VL - 617

SP - 707

EP - 717

JO - Astrophysical Journal

JF - Astrophysical Journal

SN - 0004-637X

IS - 2 I

ER -