Lyman Continuum Escape Fraction of Star-forming Dwarf Galaxies at z∼1

Authors

Michael Rutkowski, Minnesota State University, Mankato
Claudia Scarlata, University of MinnesotaFollow
Francesco Haardt, Università dell’InsubriaFollow
Brian Siana, University of California, RiversideFollow
Alaina Henry, Goddard Space Flight CenterFollow
Marc Rafelski, Goddard Space Flight CenterFollow
Matthew Hayes, Stockholm UniversityFollow
Mara Salvato, Max Planck Society
Anthony Pahl, University of MinnesotaFollow
Vihang Mehta, University of MinnesotaFollow
Melanie Beck, University of MinnesotaFollow
Matthew Malkan, University of California, Los AngelesFollow
Harry Teplitz, California Institute of TechnologyFollow

Document Type

Article

Publication Date

2016

Abstract

To date, no direct detection of Lyman continuum emission has been measured for intermediate-redshift () star-forming galaxies. We combine Hubble Space Telescope grism spectroscopy with GALEX UV and ground-based optical imaging to extend the search for escaping Lyman continuum to a large (∼600) sample of low-mass ( 9.3), moderately star-forming ( ≲ 10 yr−1) galaxies selected initially on Hα emission. The characteristic escape fraction of LyC from star-forming galaxies (SFGs) that populate this parameter space remains weakly constrained by previous surveys, but these faint (sub-L⋆) SFGs are assumed to play a significant role in the reionization of neutral hydrogen in the intergalactic medium (IGM) at high redshift . We do not make an unambiguous detection of escaping LyC radiation from this sample, individual non-detections to constrain the absolute Lyman continuum escape fraction, (3σ). We measure an upper limit of from a sample of SFGs selected on high Hα equivalent width (EW ), which are thought to be close analogs of high redshift sources of reionization. For reference, we also present an emissivity-weighted escape fraction that is useful for measuring the general contribution SFGs to the ionizing UV background. In the discussion, we consider the implications of these intermediate redshift constraints for the reionization of hydrogen in the IGM at high () redshift. If we assume our SFGs, for which we measure this emissivity-weighted , are analogs to the high redshift sources of reionization, we find it is difficult to reconcile reionization by faint () SFGs with a low escape fraction (), with constraints from independent high redshift observations. If evolves with redshift, reionization by SFGs may be consistent with observations from Planck.

Department

Physics and Astronomy

Print ISSN

0004-637X

Online ISSN

1538-4357

Publication Title

The Astrophysical Journal

Recommended Citation

Rutkowski, M., Scarlata, C., Haardt, F., Siana, B., Henry, A., Rafelski, M., Hayes, M., Salvato, M., Pahl, A., Mehta, V., Beck, M., Malkan, M., & Teplitz, H. (2016). Lyman continuum escape fraction of star-forming dwarf galaxies at z~1. The Astrophysical Journal, 819(1), Article 81. https://doi.org/10.3847/0004-637X/819/1/81

DOI

10.3847/0004-637X/819/1/81

Link to Publisher Version (DOI)

https://doi.org/10.3847/0004-637X/819/1/81

Publisher's Copyright and Source

Copyright © 2016. The American Astronomical Society. All rights reserved.