HST UV imaging of ionizing flux escaping from high-redshift galaxies
Abstract
During cosmic reionization (z~14-6), the universe went from being entirely neutral to almost completely ionized. The main contributors to the ionizing ultraviolet (UV) flux during reionization are likely to be young star-forming galaxies, as active galactic nuclei alone appear to be insufficient. Neutral gas along the line of sight to distant galaxies acts as an opaque veil to this ionizing radiation, preventing us from measuring it directly at z >~5. Therefore, identifying galaxies as close to this redshift as possible that exhibit escaping ionizing flux, observed as continuum below the Lyman break at λ<912 A, is imperative to understanding cosmic reionization. We present one of the largest high-redshift samples (z = 3-4) of these Lyman continuum galaxies (LCGs). This elusive population has been missed in searches for high-redshift star-forming galaxies typically selected with the classic Lyman break technique, due to the non-zero flux where a break is expected. We developed a novel and less biased selection method to identify this rare population, and spectroscopic redshifts have confirmed its reliability. We present extremely deep Wide Field Camera 3 rest-frame far-UV Hubble Space Telescope images of a subset of these sources. Their properties, morphologies, escape fractions and distribution reveal vital clues for understanding the role of LCGs in reionizing the universe.
- Publication:
-
American Astronomical Society Meeting Abstracts #235
- Pub Date:
- January 2020
- Bibcode:
- 2020AAS...23514703P