Testing an indirect method for identifying galaxies with high levels of Lyman continuum leakage

Satoshi Yamanaka*, Akio K. Inoue, Toru Yamada, Erik Zackrisson, Ikuru Iwata, Genoveva Micheva, Ken Mawatari, Takuya Hashimoto, Mariko Kubo

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

6 Citations (Scopus)


Using a sample of galaxies at z ≈ 3 with detected Lyman Continuum (LyC) leakage in the SSA22 field, we attempt to verify a proposed indirect method for identifying cases with high LyC escape fraction fesc based on measurements of the H β equivalent width (EW) and the β slope of the UV continuum. To this end, we present Keck/MOSFIRE H β emission line flux measurements of LyC galaxies (LCGs) at spectroscopic redshifts zspec ∼3.3, Lyman break galaxies (LBGs) at photometric redshifts zphot = 2.7-3.7, and Ly α emitters at zphot = 3.1. We also reconfirm the spectroscopic redshifts and measure the H β emission-line fluxes from two LCGs and six LBGs. For the LCG in our sample with the most extreme fesc, as revealed by the direct detection of LyC photons, we find that the EW(H β)-β method gives a broadly consistent estimate for fesc, although the error bars remain very large. We also discuss how a combination of fesc measurements based on direct and indirect methods can shed light on the LyC escape mechanism and the anisotropy of the leakage.

Original languageEnglish
Pages (from-to)3095-3114
Number of pages20
JournalMonthly Notices of the Royal Astronomical Society
Issue number3
Publication statusPublished - 2020 Nov 1


  • galaxies: ISM
  • galaxies: high-redshift
  • galaxies: starburst

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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