ON THE DETECTION OF IONIZING RADIATION ARISING FROM STAR-FORMING GALAXIES AT REDSHIFT z {approx} 3-4: LOOKING FOR ANALOGS OF 'STELLAR RE-IONIZERS'
- INAF Osservatorio Astronomico di Trieste, Via G.B. Tiepolo 11, 34131 Trieste (Italy)
- Department of Astronomy, University of Massachusetts, 710 North Pleasant Street, Amherst, MA 01003 (United States)
- INAF Osservatorio Astronomico di Roma, Via Frascati 33, 00040 Monteporzio (RM) (Italy)
- National Optical Astronomy Observatory, P.O. Box 26732, Tucson, AZ 85726 (United States)
- UCO/Lick Observatory, University of California, Santa Cruz, CA 95064 (United States)
- Space Telescope Science Institute, Baltimore, MD 21218 (United States)
- Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, PA 15260 (United States)
We use the spatially resolved, multi-band photometry in the GOODS South field acquired by the CANDELS project to constrain the nature of candidate Lyman continuum (LyC) emitters at redshift z {approx} 3.7 identified using ultradeep imaging below the Lyman limit (1{sigma} limit of Almost-Equal-To 30 AB in a 2'' diameter aperture). In 19 candidates out of a sample of 20 with flux detected at >3{sigma} level, the light centroid of the candidate LyC emission is offset from that of the Lyman break galaxy (LBG) by up to 1.''5. We fit the spectral energy distribution of the LyC candidates to spectral population synthesis models to measure photometric redshifts and the stellar population parameters. We also discuss the differences in the UV colors between the LBG and the LyC candidates, and how to estimate the escape fraction of ionizing radiation (f{sub esc}) in cases, like in most of our galaxies, where the LyC emission is spatially offset from the host galaxy. In all but one case we conclude that the candidate LyC emission is most likely due to lower redshift interlopers. Based on these findings, we argue that the majority of similar measurements reported in the literature need further investigation before it can be firmly concluded that LyC emission is detected. Our only surviving LyC candidate is an LBG at z = 3.795, which shows the bluest (B - V) color among LBGs at similar redshift, a stellar mass of M {approx} 2 Multiplication-Sign 10{sup 9} M{sub Sun }, weak interstellar absorption lines, and a flat UV spectral slope with no Ly{alpha} in emission. We estimate its f{sub esc} to be in the range 25%-100%, depending on the dust and intergalactic attenuation.
- OSTI ID:
- 22037215
- Journal Information:
- Astrophysical Journal, Vol. 751, Issue 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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