The Redshift Evolution of Rest-UV Spectroscopic Properties in Lyman-break Galaxies at z ∼ 2-4

Xinnan Du, Alice E. Shapley, Naveen A. Reddy, Tucker Jones, Daniel P Stark, Charles C. Steidel, Allison L. Strom, Gwen C. Rudie, Dawn K. Erb, Richard S. Ellis, Max Pettini

Research output: Contribution to journalArticle

8 Citations (Scopus)

Abstract

We present the first comprehensive evolutionary analysis of the rest-frame UV spectroscopic properties of star-forming galaxies at z ∼ 2-4. We match samples at different redshifts in UV luminosity and stellar mass, and perform systematic measurements of spectral features and stellar population modeling. By creating composite spectra grouped according to Lyα equivalent width (EW) and various galaxy properties, we study the evolutionary trends among Lyα, low- and high-ionization interstellar (LIS and HIS) absorption features, and integrated galaxy properties. We also examine the redshift evolution of Lyα and LIS absorption kinematics, and fine-structure emission EWs. The connections among the strengths of Lyα, LIS lines, and dust extinction are redshift independent, as is the decoupling of the Lyα and HIS line strengths, and the bulk outflow kinematics as traced by the LIS lines. Stronger Lyα emission is observed at higher redshift at fixed UV luminosity, stellar mass, SFR, and age. Much of this variation in the average Lyα strength with redshift, and the variation in Lyα strength at fixed redshift, can be explained in terms of variations in the neutral gas covering fraction and/or dust content in the ISM and CGM. However, based on the connection between Lyα and C iii] emission strengths, we additionally find evidence for variations in the intrinsic production rate of Lyα photons at the highest Lyα EWs. The challenge now is to understand the observed evolution of the neutral gas covering fraction and dust extinction within a coherent model for galaxy formation, and make robust predictions for the escape of ionizing radiation at z > 6.

Original languageEnglish (US)
Article number75
JournalAstrophysical Journal
Volume860
Issue number1
DOIs
StatePublished - Jun 10 2018

Fingerprint

land information system
galaxies
dust
neutral gases
stellar mass
ionization
kinematics
extinction
population modeling
coverings
luminosity
gas
galactic evolution
outflow
ionizing radiation
decoupling
escape
fine structure
trends
stars

Keywords

  • galaxies: evolution
  • galaxies: high-redshift
  • galaxies: ISM

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this

The Redshift Evolution of Rest-UV Spectroscopic Properties in Lyman-break Galaxies at z ∼ 2-4. / Du, Xinnan; Shapley, Alice E.; Reddy, Naveen A.; Jones, Tucker; Stark, Daniel P; Steidel, Charles C.; Strom, Allison L.; Rudie, Gwen C.; Erb, Dawn K.; Ellis, Richard S.; Pettini, Max.

In: Astrophysical Journal, Vol. 860, No. 1, 75, 10.06.2018.

Research output: Contribution to journalArticle

Du, X, Shapley, AE, Reddy, NA, Jones, T, Stark, DP, Steidel, CC, Strom, AL, Rudie, GC, Erb, DK, Ellis, RS & Pettini, M 2018, 'The Redshift Evolution of Rest-UV Spectroscopic Properties in Lyman-break Galaxies at z ∼ 2-4', Astrophysical Journal, vol. 860, no. 1, 75. https://doi.org/10.3847/1538-4357/aabfcf
Du, Xinnan ; Shapley, Alice E. ; Reddy, Naveen A. ; Jones, Tucker ; Stark, Daniel P ; Steidel, Charles C. ; Strom, Allison L. ; Rudie, Gwen C. ; Erb, Dawn K. ; Ellis, Richard S. ; Pettini, Max. / The Redshift Evolution of Rest-UV Spectroscopic Properties in Lyman-break Galaxies at z ∼ 2-4. In: Astrophysical Journal. 2018 ; Vol. 860, No. 1.
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AB - We present the first comprehensive evolutionary analysis of the rest-frame UV spectroscopic properties of star-forming galaxies at z ∼ 2-4. We match samples at different redshifts in UV luminosity and stellar mass, and perform systematic measurements of spectral features and stellar population modeling. By creating composite spectra grouped according to Lyα equivalent width (EW) and various galaxy properties, we study the evolutionary trends among Lyα, low- and high-ionization interstellar (LIS and HIS) absorption features, and integrated galaxy properties. We also examine the redshift evolution of Lyα and LIS absorption kinematics, and fine-structure emission EWs. The connections among the strengths of Lyα, LIS lines, and dust extinction are redshift independent, as is the decoupling of the Lyα and HIS line strengths, and the bulk outflow kinematics as traced by the LIS lines. Stronger Lyα emission is observed at higher redshift at fixed UV luminosity, stellar mass, SFR, and age. Much of this variation in the average Lyα strength with redshift, and the variation in Lyα strength at fixed redshift, can be explained in terms of variations in the neutral gas covering fraction and/or dust content in the ISM and CGM. However, based on the connection between Lyα and C iii] emission strengths, we additionally find evidence for variations in the intrinsic production rate of Lyα photons at the highest Lyα EWs. The challenge now is to understand the observed evolution of the neutral gas covering fraction and dust extinction within a coherent model for galaxy formation, and make robust predictions for the escape of ionizing radiation at z > 6.

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