Galaxies in the first billion years after the big bang

Research output: Contribution to journalArticle

57 Citations (Scopus)

Abstract

In the past five years, deep imaging campaigns conducted with the Hubble Space Telescope (HST) and ground-based observatories have delivered large samples of galaxies at 6.5<z<10, providing our first glimpse of the census of star formation activity in what is thought to be the heart of the reionization era. The space density of luminous galaxies has been shown to decrease by 15-20× over 4<z<8. Over this same redshift interval, the faint-end slope of the UV luminosity function becomes steeper (α≃-2.0 at z≃7-8), revealing a dominant population of low-luminosity galaxies. Analysis of multiwavelength imaging from HST and the Spitzer Space Telescope demonstrates that z>6 UV-selected galaxies are relatively compact with blue UV continuum slopes, low stellar masses, and large specific star formation rates. In the last year, ALMA (the Atacama Large Millimeter Array) and ground-based infrared spectrographs have begun to complement this picture, revealing minimal dust obscuration and hard radiation fields, and providing evidence for metal-poor ionized gas. Weak low-ionization absorption lines suggest a patchy distribution of neutral gas surrounds O and B stars, possibly aiding in the escape of ionizing radiation. Gamma ray burst afterglows and Lyman-α surveys have provided evidence that the intergalactic medium (IGM) evolves from mostly ionized at z≃6-6.5 () to considerably neutral at z≃7-8 (). The reionization history that emerges from considering the UV output of galaxies over 6<z<10 is consistent with these constraints on the IGM ionization state. The latest measurements suggest that galaxies can complete reionization by z≃6 and reproduce the Thomson scattering optical depth faced by cosmic microwave background photons if the luminosity function extends ≃4 mag below current surveys and a moderate fraction () of ionizing radiation escapes from galaxies.

Original languageEnglish (US)
Pages (from-to)761-803
Number of pages43
JournalAnnual Review of Astronomy and Astrophysics
Volume54
DOIs
StatePublished - Sep 19 2016

Fingerprint

ionization
galaxies
gas
intergalactic media
optical depth
observatory
ionizing radiation
scattering
escape
dust
metal
history
O stars
B stars
Thomson scattering
neutral gases
occultation
ionized gases
star formation rate
stellar mass

Keywords

  • Cosmology
  • Galaxy evolution
  • Galaxy formation
  • Reionization

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this

Galaxies in the first billion years after the big bang. / Stark, Daniel P.

In: Annual Review of Astronomy and Astrophysics, Vol. 54, 19.09.2016, p. 761-803.

Research output: Contribution to journalArticle

@article{7cdadd0f108f4af8a188ba65642a7563,
title = "Galaxies in the first billion years after the big bang",
abstract = "In the past five years, deep imaging campaigns conducted with the Hubble Space Telescope (HST) and ground-based observatories have delivered large samples of galaxies at 6.56 UV-selected galaxies are relatively compact with blue UV continuum slopes, low stellar masses, and large specific star formation rates. In the last year, ALMA (the Atacama Large Millimeter Array) and ground-based infrared spectrographs have begun to complement this picture, revealing minimal dust obscuration and hard radiation fields, and providing evidence for metal-poor ionized gas. Weak low-ionization absorption lines suggest a patchy distribution of neutral gas surrounds O and B stars, possibly aiding in the escape of ionizing radiation. Gamma ray burst afterglows and Lyman-α surveys have provided evidence that the intergalactic medium (IGM) evolves from mostly ionized at z≃6-6.5 () to considerably neutral at z≃7-8 (). The reionization history that emerges from considering the UV output of galaxies over 6",
keywords = "Cosmology, Galaxy evolution, Galaxy formation, Reionization",
author = "Stark, {Daniel P}",
year = "2016",
month = "9",
day = "19",
doi = "10.1146/annurev-astro-081915-023417",
language = "English (US)",
volume = "54",
pages = "761--803",
journal = "Annual Review of Astronomy and Astrophysics",
issn = "0066-4146",
publisher = "Annual Reviews Inc.",

}

TY - JOUR

T1 - Galaxies in the first billion years after the big bang

AU - Stark, Daniel P

PY - 2016/9/19

Y1 - 2016/9/19

N2 - In the past five years, deep imaging campaigns conducted with the Hubble Space Telescope (HST) and ground-based observatories have delivered large samples of galaxies at 6.56 UV-selected galaxies are relatively compact with blue UV continuum slopes, low stellar masses, and large specific star formation rates. In the last year, ALMA (the Atacama Large Millimeter Array) and ground-based infrared spectrographs have begun to complement this picture, revealing minimal dust obscuration and hard radiation fields, and providing evidence for metal-poor ionized gas. Weak low-ionization absorption lines suggest a patchy distribution of neutral gas surrounds O and B stars, possibly aiding in the escape of ionizing radiation. Gamma ray burst afterglows and Lyman-α surveys have provided evidence that the intergalactic medium (IGM) evolves from mostly ionized at z≃6-6.5 () to considerably neutral at z≃7-8 (). The reionization history that emerges from considering the UV output of galaxies over 6

AB - In the past five years, deep imaging campaigns conducted with the Hubble Space Telescope (HST) and ground-based observatories have delivered large samples of galaxies at 6.56 UV-selected galaxies are relatively compact with blue UV continuum slopes, low stellar masses, and large specific star formation rates. In the last year, ALMA (the Atacama Large Millimeter Array) and ground-based infrared spectrographs have begun to complement this picture, revealing minimal dust obscuration and hard radiation fields, and providing evidence for metal-poor ionized gas. Weak low-ionization absorption lines suggest a patchy distribution of neutral gas surrounds O and B stars, possibly aiding in the escape of ionizing radiation. Gamma ray burst afterglows and Lyman-α surveys have provided evidence that the intergalactic medium (IGM) evolves from mostly ionized at z≃6-6.5 () to considerably neutral at z≃7-8 (). The reionization history that emerges from considering the UV output of galaxies over 6

KW - Cosmology

KW - Galaxy evolution

KW - Galaxy formation

KW - Reionization

UR - http://www.scopus.com/inward/record.url?scp=84988851062&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84988851062&partnerID=8YFLogxK

U2 - 10.1146/annurev-astro-081915-023417

DO - 10.1146/annurev-astro-081915-023417

M3 - Article

AN - SCOPUS:84988851062

VL - 54

SP - 761

EP - 803

JO - Annual Review of Astronomy and Astrophysics

JF - Annual Review of Astronomy and Astrophysics

SN - 0066-4146

ER -