The role of galaxies and agn in reionizing the IGM-I. Keck spectroscopy of 5 < z < 7 galaxies in the QSO field J1148+5251

Koki Kakiichi, Richard S. Ellis, Nicolas Laporte, Adi Zitrin, Anna Christina Eilers, Emma Ryan-Weber, Romain A. Meyer, Brant E Robertson, Daniel P Stark, Sarah E.I. Bosman

Research output: Contribution to journalArticle

8 Citations (Scopus)

Abstract

We introduce a new method for determining the influence of galaxies and active galactic nuclei (AGN) on the intergalactic medium (IGM) at high redshift and illustrate its potential via a first application to the field of the z = 6.42 QSO J1148+5251. Correlating spatial positions Lyman break galaxies (LBGs) with the Lyman alpha forest seen in the spectrum of a background QSO, we provide a statistical measure of the typical escape fraction of Lyman continuum photons. Using Keck DEIMOS spectroscopy to locate seven colour-selected LBGs in the range 5.3≲z≲6.4 we examine the spatial correlation between this sample and Lyα/Lyβ transmission fluctuations in a Keck ESI spectrum of the QSO. Interpreting the statistical HI proximity effect as arising from faint galaxies clustered around the LBGs, we translate the observed mean Lya transmitted flux into a constraint on the mean escape fraction (fesc) ≥ 0.08 at z ≃ 6. We also report individual transverse HI proximity effect for a z = 6.177 luminous LBG via a Lyβ transmission spike and two broad Lyα transmission spikes around the z = 5.701 AGN. We discuss the origin of such associations which suggest that while faint galaxies are primarily driving reionization, luminous galaxies and AGN may provide important contributions to the UV background or thermal fluctuations of the IGM at z≃6. Although a limited sample, our results demonstrate the potential of making progress using this method in resolving one of the most challenging aspects of the contribution of galaxies and AGN to cosmic reionization.

Original languageEnglish (US)
Pages (from-to)43-63
Number of pages21
JournalMonthly Notices of the Royal Astronomical Society
Volume479
Issue number1
DOIs
StatePublished - Sep 1 2018

Fingerprint

intergalactic media
quasars
spectroscopy
galaxies
active galactic nuclei
spikes
escape
effect
method
continuums
color
photons

Keywords

  • Cosmology: observations
  • Dark ages, reionization, first stars
  • Galaxies: formation
  • Galaxies: high
  • Intergalactic medium
  • Quasars: absorption lines
  • Redshift

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this

The role of galaxies and agn in reionizing the IGM-I. Keck spectroscopy of 5 < z < 7 galaxies in the QSO field J1148+5251. / Kakiichi, Koki; Ellis, Richard S.; Laporte, Nicolas; Zitrin, Adi; Eilers, Anna Christina; Ryan-Weber, Emma; Meyer, Romain A.; Robertson, Brant E; Stark, Daniel P; Bosman, Sarah E.I.

In: Monthly Notices of the Royal Astronomical Society, Vol. 479, No. 1, 01.09.2018, p. 43-63.

Research output: Contribution to journalArticle

Kakiichi, Koki ; Ellis, Richard S. ; Laporte, Nicolas ; Zitrin, Adi ; Eilers, Anna Christina ; Ryan-Weber, Emma ; Meyer, Romain A. ; Robertson, Brant E ; Stark, Daniel P ; Bosman, Sarah E.I. / The role of galaxies and agn in reionizing the IGM-I. Keck spectroscopy of 5 < z < 7 galaxies in the QSO field J1148+5251. In: Monthly Notices of the Royal Astronomical Society. 2018 ; Vol. 479, No. 1. pp. 43-63.
@article{a48fb4ab58da42bd8b2f29708498edc6,
title = "The role of galaxies and agn in reionizing the IGM-I. Keck spectroscopy of 5 < z < 7 galaxies in the QSO field J1148+5251",
abstract = "We introduce a new method for determining the influence of galaxies and active galactic nuclei (AGN) on the intergalactic medium (IGM) at high redshift and illustrate its potential via a first application to the field of the z = 6.42 QSO J1148+5251. Correlating spatial positions Lyman break galaxies (LBGs) with the Lyman alpha forest seen in the spectrum of a background QSO, we provide a statistical measure of the typical escape fraction of Lyman continuum photons. Using Keck DEIMOS spectroscopy to locate seven colour-selected LBGs in the range 5.3≲z≲6.4 we examine the spatial correlation between this sample and Lyα/Lyβ transmission fluctuations in a Keck ESI spectrum of the QSO. Interpreting the statistical HI proximity effect as arising from faint galaxies clustered around the LBGs, we translate the observed mean Lya transmitted flux into a constraint on the mean escape fraction (fesc) ≥ 0.08 at z ≃ 6. We also report individual transverse HI proximity effect for a z = 6.177 luminous LBG via a Lyβ transmission spike and two broad Lyα transmission spikes around the z = 5.701 AGN. We discuss the origin of such associations which suggest that while faint galaxies are primarily driving reionization, luminous galaxies and AGN may provide important contributions to the UV background or thermal fluctuations of the IGM at z≃6. Although a limited sample, our results demonstrate the potential of making progress using this method in resolving one of the most challenging aspects of the contribution of galaxies and AGN to cosmic reionization.",
keywords = "Cosmology: observations, Dark ages, reionization, first stars, Galaxies: formation, Galaxies: high, Intergalactic medium, Quasars: absorption lines, Redshift",
author = "Koki Kakiichi and Ellis, {Richard S.} and Nicolas Laporte and Adi Zitrin and Eilers, {Anna Christina} and Emma Ryan-Weber and Meyer, {Romain A.} and Robertson, {Brant E} and Stark, {Daniel P} and Bosman, {Sarah E.I.}",
year = "2018",
month = "9",
day = "1",
doi = "10.1093/mnras/sty1318",
language = "English (US)",
volume = "479",
pages = "43--63",
journal = "Monthly Notices of the Royal Astronomical Society",
issn = "0035-8711",
publisher = "Oxford University Press",
number = "1",

}

TY - JOUR

T1 - The role of galaxies and agn in reionizing the IGM-I. Keck spectroscopy of 5 < z < 7 galaxies in the QSO field J1148+5251

AU - Kakiichi, Koki

AU - Ellis, Richard S.

AU - Laporte, Nicolas

AU - Zitrin, Adi

AU - Eilers, Anna Christina

AU - Ryan-Weber, Emma

AU - Meyer, Romain A.

AU - Robertson, Brant E

AU - Stark, Daniel P

AU - Bosman, Sarah E.I.

PY - 2018/9/1

Y1 - 2018/9/1

N2 - We introduce a new method for determining the influence of galaxies and active galactic nuclei (AGN) on the intergalactic medium (IGM) at high redshift and illustrate its potential via a first application to the field of the z = 6.42 QSO J1148+5251. Correlating spatial positions Lyman break galaxies (LBGs) with the Lyman alpha forest seen in the spectrum of a background QSO, we provide a statistical measure of the typical escape fraction of Lyman continuum photons. Using Keck DEIMOS spectroscopy to locate seven colour-selected LBGs in the range 5.3≲z≲6.4 we examine the spatial correlation between this sample and Lyα/Lyβ transmission fluctuations in a Keck ESI spectrum of the QSO. Interpreting the statistical HI proximity effect as arising from faint galaxies clustered around the LBGs, we translate the observed mean Lya transmitted flux into a constraint on the mean escape fraction (fesc) ≥ 0.08 at z ≃ 6. We also report individual transverse HI proximity effect for a z = 6.177 luminous LBG via a Lyβ transmission spike and two broad Lyα transmission spikes around the z = 5.701 AGN. We discuss the origin of such associations which suggest that while faint galaxies are primarily driving reionization, luminous galaxies and AGN may provide important contributions to the UV background or thermal fluctuations of the IGM at z≃6. Although a limited sample, our results demonstrate the potential of making progress using this method in resolving one of the most challenging aspects of the contribution of galaxies and AGN to cosmic reionization.

AB - We introduce a new method for determining the influence of galaxies and active galactic nuclei (AGN) on the intergalactic medium (IGM) at high redshift and illustrate its potential via a first application to the field of the z = 6.42 QSO J1148+5251. Correlating spatial positions Lyman break galaxies (LBGs) with the Lyman alpha forest seen in the spectrum of a background QSO, we provide a statistical measure of the typical escape fraction of Lyman continuum photons. Using Keck DEIMOS spectroscopy to locate seven colour-selected LBGs in the range 5.3≲z≲6.4 we examine the spatial correlation between this sample and Lyα/Lyβ transmission fluctuations in a Keck ESI spectrum of the QSO. Interpreting the statistical HI proximity effect as arising from faint galaxies clustered around the LBGs, we translate the observed mean Lya transmitted flux into a constraint on the mean escape fraction (fesc) ≥ 0.08 at z ≃ 6. We also report individual transverse HI proximity effect for a z = 6.177 luminous LBG via a Lyβ transmission spike and two broad Lyα transmission spikes around the z = 5.701 AGN. We discuss the origin of such associations which suggest that while faint galaxies are primarily driving reionization, luminous galaxies and AGN may provide important contributions to the UV background or thermal fluctuations of the IGM at z≃6. Although a limited sample, our results demonstrate the potential of making progress using this method in resolving one of the most challenging aspects of the contribution of galaxies and AGN to cosmic reionization.

KW - Cosmology: observations

KW - Dark ages, reionization, first stars

KW - Galaxies: formation

KW - Galaxies: high

KW - Intergalactic medium

KW - Quasars: absorption lines

KW - Redshift

UR - http://www.scopus.com/inward/record.url?scp=85051540541&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85051540541&partnerID=8YFLogxK

U2 - 10.1093/mnras/sty1318

DO - 10.1093/mnras/sty1318

M3 - Article

AN - SCOPUS:85051540541

VL - 479

SP - 43

EP - 63

JO - Monthly Notices of the Royal Astronomical Society

JF - Monthly Notices of the Royal Astronomical Society

SN - 0035-8711

IS - 1

ER -