Searching for candidates of Lyman continuum sources – revisiting the SSA22 field

We present the largest to date sample of hydrogen Lyman continuum (LyC) emitting galaxy candidates at any redshift, with 18 Lyman alpha emitters (LAEs) and seven Lyman break galaxies (LBGs), obtained from the SSA22 field with Subaru/Suprime-Cam. The sample is based on the 159 LAEs and 136 LBGs obser...

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Bibliographic Details
Published in:Monthly notices of the Royal Astronomical Society 2017-02, Vol.465 (1), p.316-316
Main Authors: Micheva, Genoveva, Iwata, Ikuru, Inoue, Akio K, Matsuda, Yuichi, Yamada, Toru, Hayashino, Tomoki
Format: Article
Language:English
Subjects:
Atoms & subatomic particles
Contamination
Continuums
Emitters
Galaxies
Hydrogen
Red shift
Samples
Stacking
Stars & galaxies
Statistical analysis
Statistical methods
Ultraviolet radiation
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Summary:We present the largest to date sample of hydrogen Lyman continuum (LyC) emitting galaxy candidates at any redshift, with 18 Lyman alpha emitters (LAEs) and seven Lyman break galaxies (LBGs), obtained from the SSA22 field with Subaru/Suprime-Cam. The sample is based on the 159 LAEs and 136 LBGs observed in the field, all with spectroscopically confirmed redshifts, and these LyC candidates are selected as galaxies with counterparts in a narrow-band filter image which traces LyC at z greater than or equal to 3.06. Many LyC candidates show a spatial offset between the rest-frame non-ionizing ultraviolet (UV) detection and the LyC-emitting substructure or between the Ly alpha emission and LyC. The possibility of foreground contamination complicates the analysis of the nature of LyC emitters, although statistically it is highly unlikely that all candidates in our sample are contaminated by foreground sources. Many viable LyC LAE candidates have flux density ratios inconsistent with standard models, while also having too blue UV slopes to be foreground contaminants. Stacking reveals no significant LyC detection, suggesting that there is a dearth of objects with marginal LyC signal strength, perhaps due to a bimodality in the LyC emission. The foreground contamination corrected 3 sigma upper limits of the observed average flux density ratios are f sub( LyC)/f sub( UV) < 0.08 from stacking LAEs and f sub( LyC)/f sub( UV) < 0.02 from stacking LBGs. There is a sign of a positive correlation between LyC and Ly alpha , suggesting that both types of photons escape via a similar mechanism. The LyC detection rate among protocluster LBGs is seemingly lower compared to the field.
ISSN:0035-8711
1365-2966
DOI:10.1093/mnras/stw2700