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Near Field Cosmology: Characterizing the Properties Leading to Radiation Leakage in Local Low- and Intermediate-Mass Galaxies
The escape of radiation from galaxies is a frontier cosmology problem with wide-ranging implications for reionization, galaxy evolution and detection strategies for high-redshift systems. Low- and intermediate-mass galaxies may have played a crucial role in reionization at early times, and by studying their analogues in the local universe, we can test models of radiation escape in galaxies that are more observationally accessible. We present here our cross-sectional analyses of the characteristics of low-redshift galaxies from surveys including KISSR, LARS, and two Green Pea galaxy samples through various computational and visualization techniques. Local systems with measured high (> 0.1) Lyman-alpha escape fractions tend to have high equivalent widths in H-alpha (EWHA) and low Lyman-alpha red-peak velocity. The KISSR systems contain a population, in appearance resembling "purple peas", with potentially steep UV slopes and high EWHA (please see accompanying poster by Olivieri Villalvazo et al. at this meeting). These might represent a population of local starforming galaxies that are more common than, e.g., Green Pea galaxies, that also have potentially high Lyman-alpha, and likely Lyman-continuum, escape. These galaxies could potentially test theoretical models and advance studies of the "first-light" galaxies anticipated from the James Webb Space Telescope through characterizing the underlying physical more »
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Publication Date:
NSF-PAR ID:
10097663
Journal Name:
American Astronomical Society, AAS Meeting
Volume:
233
Page Range or eLocation-ID:
383.04
Sponsoring Org:
National Science Foundation
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1. We present our analyses of 39 selected star-forming low- to intermediate-mass low-redshift galaxies from the KISSR survey. These galaxies were selected as being representative in the local volume of the kinds of early galaxies that might have hosted the first stars, and span a range of galaxy properties (EWHA, reddening, metallicity, stellar mass). The KISSR systems contain a population, in appearance resembling "purple peas", with potentially steep UV slopes and high equivalent widths in H-alpha. Using archival GALEX data and theoretical models of radiation transport in dusty galaxies with clumpy gas media, we translate measurements of the UV slopes of these low-mass low-z KISSR galaxies to their escape fractions in Ly-alpha (LyA) and Ly-continuum (LyC) radiation, confirming a relationship between a galaxy's steep UV spectral slope and a significant (> 0.1) LyA escape fraction. This relationship is seen in existing data of low- to intermediate-mass galaxies in the local volume (please see accompanying poster by Pilon et al. at this meeting). We also translate measured LyA escape fractions in the literature for 14 LARS galaxies and a few dozen green pea galaxies to their LyC escape fractions using similar modeling. This work was supported by the University of San Franciscomore »
2. We present our results on calculations of the escape of Ly-alpha and Ly-continuum radiation from low- and intermediate-mass galaxies. Such systems may have played a crucial role in reionization at early times. We use simple analytic models for the underlying galaxy profiles and compare them with semi-analytic and numerical computations of escaping radiation from such systems. We comment on the possible range of values for the critical spectral index of the source radiation at which H and He ionization start to compete, under a variety of physical conditions. Last, we examine data of low- and intermediate-mass galaxy populations in the local volume, including strong-emission line systems like green pea galaxies and Ly-alpha emitting systems, that closely resemble the earliest halos that hosted the first stars. We share a set of observable galaxy properties that could characterize the "leakers", whose high-redshift counterparts would have had significant escape of Ly-alpha and Ly-continuum radiation. This work was supported by the University of San Francisco (USF) Faculty Development Fund, the USF Student Travel Fund, and by the Undergraduate ALFALFA Team through NSF grant AST-1637339.
3. ABSTRACT

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4. ABSTRACT

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5. Abstract

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