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Searching for the connection between ionizing-photon escape and the surface density of star formation at z ∼ 3

Pahl, Anthony J. and Shapley, Alice and Steidel, Charles C. and Reddy, Naveen A. and Chen, Yuguang (2022) Searching for the connection between ionizing-photon escape and the surface density of star formation at z ∼ 3. Monthly Notices of the Royal Astronomical Society, 516 (2). pp. 2062-2073. ISSN 0035-8711. doi:10.1093/mnras/stac1767.

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The connection between the escape fraction of ionizing photons (f_(esc)) and star formation rate surface density (Σ_(SFR)) is a key input for reionization models, but remains untested at high redshift. We analyse 35 z ∼ 3 galaxies from the Keck Lyman Continuum Survey (KLCS) covered by deep, rest far-UV spectra of the Lyman continuum (LyC) and high-resolution HST V_(606) imaging, enabling estimates of both f_(esc) and rest-UV sizes. Using Sérsic profile fits to HST images and spectral-energy distribution fits to multiband photometry, we measure effective sizes and SFRs for the galaxies in our sample, and separate the sample into two bins of Σ_(SFR). Based on composite spectra, we estimate 〈f_(esc)〉 for both Σ_(SFR) subsamples, finding no significant difference in 〈f_(esc)〉 between the two. To test the representativeness of the KLCS HST sample and robustness of this result, we attempt to recover the well-established correlation between f_(esc) and Lyα equivalent width. This correlation is not significant within the KLCS HST sample, indicating that the sample is insufficient for correlating f_(esc) and galaxy properties such as Σ_(SFR). We perform stacking simulations using the KLCS parent sample to determine the optimal sample size for robust probes of the f_(esc)-Σ_(SFR) connection to inform future observing programs. For a program with a selection independent of ionizing properties, ≥90 objects are required; for one preferentially observing strongly-leaking LyC sources, ≥58 objects are required. More generally, measuring the connection between f_(esc) and Σ_(SFR) requires a larger, representative sample spanning a wide dynamic range in galaxies properties such as Σ_(SFR).

Item Type:Article
Related URLs:
URLURL TypeDescription
Pahl, Anthony J.0000-0003-4464-4505
Shapley, Alice0000-0003-3509-4855
Steidel, Charles C.0000-0002-4834-7260
Reddy, Naveen A.0000-0001-9687-4973
Chen, Yuguang0000-0003-4520-5395
Additional Information:We acknowledge support from NSF AAG grants 0606912, 0908805, 1313472 2009313, 2009085, and 2009278. Support for program HST-GO-15287.001 was provided by NASA through a grant from the Space Telescope Science Institute, which is operated by the Associations of Universities for Research in Astronomy, Incorporated, under NASA contract NAS5-26555. CS was supported in part by the Caltech/JPL President’s and Director’s program. Based on observations obtained with MegaPrime/MegaCam, a joint project of CFHT and CEA/IRFU, at the Canada-France-Hawaii Telescope (CFHT) which is operated by the National Research Council (NRC) of Canada, the Institut National des Science de l’Univers of the Centre National de la Recherche Scientifique (CNRS) of France, and the University of Hawaii. This work is based in part on data products produced at Terapix available at the Canadian Astronomy Data Centre as part of the CFHT Legacy Survey, a collaborative project of NRC and CNRS. We wish to extend special thanks to those of Hawaiian ancestry on whose sacred mountain we are privileged to be guests. Without their generous hospitality, most of the observations presented herein would not have been possible.
Group:Astronomy Department
Funding AgencyGrant Number
JPL President and Director's FundUNSPECIFIED
Issue or Number:2
Record Number:CaltechAUTHORS:20220926-576554400.10
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:117143
Deposited By: Melissa Ray
Deposited On:04 Oct 2022 16:49
Last Modified:04 Oct 2022 16:49

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