The far-ultraviolet continuum slope as a Lyman Continuum escape estimator at high redshift-Reference-Cited by-同舟云学术

The far-ultraviolet continuum slope as a Lyman Continuum escape estimator at high redshift

Published:2022-10-07 Issue:4 Volume:517 Page:5104-5120
ISSN:0035-8711
Container-title:Monthly Notices of the Royal Astronomical Society
language:en
Short-container-title:

Author:

Chisholm J¹^ORCID,Saldana-Lopez A²^ORCID,Flury S³,Schaerer D²⁴,Jaskot A⁵,Amorín R⁶⁷^ORCID,Atek H⁸,Finkelstein S L¹,Fleming B⁹,Ferguson H¹⁰,Fernández V⁶,Giavalisco M³,Hayes M¹¹^ORCID,Heckman T¹²,Henry A¹⁰,Ji Z³,Marques-Chaves R²,Mauerhofer V¹³,McCandliss S¹²,Oey M S¹⁴,Östlin G¹¹,Rutkowski M¹⁵,Scarlata C¹⁶^ORCID,Thuan T¹⁷,Trebitsch M¹³^ORCID,Wang B¹⁸^ORCID,Worseck G¹⁹^ORCID,Xu X¹²^ORCID

Affiliation:

1. Department of Astronomy, The University of Texas at Austin , 2515 Speedway, Stop C1400, Austin, TX 78712-1205, USA

2. Department of Astronomy, University of Geneva , 51 Chemin Pegasi, CH-1290 Versoix, Switzerland

3. Department of Astronomy, University of Massachusetts Amherst , Amherst, MA 01002, USA

4. CNRS , IRAP, 14 Avenue E. Belin, F-31400 Toulouse, France

5. Department of Astronomy, Williams College , Williamstown, MA 01267, USA

6. Departamento de Astronomía, Universidad de La Serena , Av. Juan Cisternas 1200 Norte, La Serena, Chile

7. Instituto de Investigación Multidisciplinar en Ciencia y Tecnología, Universidad de La Serena , Raul Bitran 1305 La Serena, Chile

8. Institut d’astrophysique de Paris, CNRS UMR7095 , Sorbonne Université, 98bis Boulevard Arago, F-75014 Paris, France

9. Laboratory for Atmospheric and Space Physics , Boulder, Colorado 80303, USA

10. Space Telescope Science Institute , 3700 San Martin Drive Baltimore, MD 21218, USA

11. The Oskar Klein Centre, Department of Astronomy, Stockholm University , AlbaNova, SE-10691 Stockholm, Sweden

12. Department of Physics and Astronomy, Johns Hopkins University , Baltimore, MD 21218, USA

13. Kapteyn Astronomical Institute, University of Groningen , PO Box 800, NL-9700 AV Groningen, the Netherlands

14. Department of Astronomy, University of Michigan , Ann Arbor, MI 48109, USA

15. Department of Physics and Astronomy, Minnesota State University , Mankato, MN, 56001, USA

16. Minnesota Institute for Astrophysics, School of Physics and Astronomy, University of Minnesota , 316 Church Street SE, Minneapolis, MN 55455, USA

17. Astronomy Department, University of Virginia , Charlottesville, VA 22904, USA

18. Department of Astronomy & Astrophysics, The Pennsylvania State University , University Park, PA 16802, USA

19. Institut für Physik und Astronomie, Universität Potsdam , Karl-Liebknecht-Str 24/25, D-14476 Potsdam, Germany

Abstract

ABSTRACT Most of the hydrogen in the intergalactic medium (IGM) was rapidly ionized at high redshifts. While observations have established that reionization occurred, observational constraints on the high-redshift ionizing emissivity remain elusive. Here, we present a new analysis of the Low-redshift Lyman Continuum Survey (LzLCS) and literature observations, a combined sample of 89 star-forming galaxies at redshifts near 0.3 with Hubble Space Telescope observations of their ionizing continua (or Lyman Continuum, LyC). We find a strong (6σ significant) inverse correlation between the continuum slope at 1550 Å (defined as F$_\lambda \propto \lambda ^{\beta ^{1550}_{\rm obs}}$) and both the LyC escape fraction (fesc, LyC) and fesc, LyC times the ionizing photon production efficiency (ξion). On average, galaxies with redder continuum slopes have smaller fesc, LyC than galaxies with bluer slopes mainly due to higher dust attenuation. More than 5 per cent (20 per cent) of the LyC emission escapes galaxies with $\beta _{\rm obs}^{1550}$ <−2.1 (−2.6). We find strong correlations between $\beta _{\rm obs}^{1550}$ and the [O iii]/[O ii] flux ratio (at 7.5σ significance), galaxy stellar mass (at 5.9σ), the gas-phase metallicity (at 4.6σ), and the observed far-ultraviolet absolute magnitude (at 3.4σ). Using previous observations of $\beta _{\rm obs}^{1550}$ at high redshift, we estimate the evolution of fesc, LyC with both redshift and galaxy magnitude. The LzLCS observations suggest that fainter and lower mass galaxies dominate the ionizing photon budget at higher redshift, possibly due to their rapidly evolving metal and dust content. Finally, we use our correlation between $\beta _{\rm obs}^{1550}$ and fesc, LyC × ξion to predict the ionizing emissivity of galaxies during the epoch of reionization. Our estimated emissivities match IGM observations, and suggest that star-forming galaxies emit sufficient LyC photons into the IGM to exceed recombinations near redshifts of 7–8.

Funder

University of Texas at Austin

NASA

Space Telescope Science Institute

ESA

STScI

ASL

Swiss National Science Foundation

ANID

FONDECYT

Knut and Alice Wallenberg Foundation

Publisher