CLASSY VII Lyα Profiles: The Structure and Kinematics of Neutral Gas and Implications for LyC Escape in Reionization-era Analogs

Weida Hu; Crystal L. Martin; Max Gronke; Simon Gazagnes; Matthew Hayes; John Chisholm; Timothy Heckman; Matilde Mingozzi; Namrata Roy; Peter Senchyna; Xinfeng Xu; Danielle A. Berg; Bethan L. James; Daniel P. Stark; Karla Z. Arellano-Córdova; Alaina Henry; Anne E. Jaskot; Nimisha Kumari; Kaelee S. Parker; Claudia Scarlata; Aida Wofford; Ricardo O. Amorín; Naunet Leonhardes-Barboza; Jarle Brinchmann; Cody Carr; Alessandra Aloisi

doi:10.3847/1538-4357/aceefd

The Astrophysical Journal (Jan 2023)

CLASSY VII Lyα Profiles: The Structure and Kinematics of Neutral Gas and Implications for LyC Escape in Reionization-era Analogs

Weida Hu,
Crystal L. Martin,
Max Gronke,
Simon Gazagnes,
Matthew Hayes,
John Chisholm,
Timothy Heckman,
Matilde Mingozzi,
Namrata Roy,
Peter Senchyna,
Xinfeng Xu,
Danielle A. Berg,
Bethan L. James,
Daniel P. Stark,
Karla Z. Arellano-Córdova,
Alaina Henry,
Anne E. Jaskot,
Nimisha Kumari,
Kaelee S. Parker,
Claudia Scarlata,
Aida Wofford,
Ricardo O. Amorín,
Naunet Leonhardes-Barboza,
Jarle Brinchmann,
Cody Carr,
Alessandra Aloisi

Affiliations

Weida Hu: ORCiD; Department of Physics, University of California , Santa Barbara, Santa Barbara, CA 93106, USA
Crystal L. Martin: ORCiD; Department of Physics, University of California , Santa Barbara, Santa Barbara, CA 93106, USA
Max Gronke: ORCiD; Max-Planck Institute for Astrophysics , Karl-Schwarzschild-Str. 1, D-85741 Garching, Germany
Simon Gazagnes: ORCiD; Department of Astronomy, The University of Texas at Austin , 2515 Speedway, Stop C1400, Austin, TX 78712, USA
Matthew Hayes: ORCiD; Stockholm University , Department of Astronomy and Oskar Klein Centre for Cosmoparticle Physics, AlbaNova University Centre, SE-10691, Stockholm, Sweden
John Chisholm: ORCiD; Department of Astronomy, The University of Texas at Austin , 2515 Speedway, Stop C1400, Austin, TX 78712, USA
Timothy Heckman: ORCiD; Center for Astrophysical Sciences, Department of Physics & Astronomy, Johns Hopkins University , Baltimore, MD 21218, USA
Matilde Mingozzi: ORCiD; Space Telescope Science Institute , 3700 San Martin Drive, Baltimore, MD 21218, USA
Namrata Roy: ORCiD; Center for Astrophysical Sciences, Department of Physics & Astronomy, Johns Hopkins University , Baltimore, MD 21218, USA
Peter Senchyna: ORCiD; Carnegie Observatories , 813 Santa Barbara Street, Pasadena, CA 91101, USA
Xinfeng Xu: ORCiD; Center for Astrophysical Sciences, Department of Physics & Astronomy, Johns Hopkins University , Baltimore, MD 21218, USA
Danielle A. Berg: ORCiD; Department of Astronomy, The University of Texas at Austin , 2515 Speedway, Stop C1400, Austin, TX 78712, USA
Bethan L. James: ORCiD; AURA for ESA, Space Telescope Science Institute , 3700 San Martin Drive, Baltimore, MD 21218, USA
Daniel P. Stark: ORCiD; Steward Observatory, The University of Arizona , 933 N Cherry Avenue, Tucson, AZ 85721, USA
Karla Z. Arellano-Córdova: ORCiD; Department of Astronomy, The University of Texas at Austin , 2515 Speedway, Stop C1400, Austin, TX 78712, USA
Alaina Henry: ORCiD; Center for Astrophysical Sciences, Department of Physics & Astronomy, Johns Hopkins University , Baltimore, MD 21218, USA; Space Telescope Science Institute , 3700 San Martin Drive, Baltimore, MD 21218, USA
Anne E. Jaskot: ORCiD; Department of Astronomy, Williams College , Williams town, MA 01267, USA
Nimisha Kumari: ORCiD; AURA for ESA, Space Telescope Science Institute , 3700 San Martin Drive, Baltimore, MD 21218, USA
Kaelee S. Parker: ORCiD; Department of Astronomy, The University of Texas at Austin , 2515 Speedway, Stop C1400, Austin, TX 78712, USA
Claudia Scarlata: ORCiD; Minnesota Institute for Astrophysics, University of Minnesota , 116 Church Street SE, Minneapolis, MN 55455, USA
Aida Wofford: ORCiD; Instituto de Astronomía, Universidad Nacional Autónoma de México , Unidad Académica en Ensenada, Km 103 Carr. Tijuana-Ensenada, Ensenada 22860, Mexico
Ricardo O. Amorín: ORCiD; Instituto de Investigación Multidisciplinar en Ciencia y Tecnología, Universidad de La Serena , Raul Bitrán 1305, La Serena 2204000, Chile; Departamento de Astronomía, Universidad de La Serena , Av. Juan Cisternas 1200 Norte, La Serena 1720236, Chile
Naunet Leonhardes-Barboza: Wellesley College , 106 Central Street, Wellesley, MA 02481, USA
Jarle Brinchmann: ORCiD; Instituto de Astrofísica e Ciências do Espaço, Universidade do Porto , CAUP, Rua das Estrelas, PT4150-762 Porto, Portugal
Cody Carr: ORCiD; Minnesota Institute for Astrophysics, University of Minnesota , 116 Church Street SE, Minneapolis, MN 55455, USA
Alessandra Aloisi: ORCiD; Space Telescope Science Institute , 3700 San Martin Drive, Baltimore, MD 21218, USA

DOI: https://doi.org/10.3847/1538-4357/aceefd
Journal volume & issue: Vol. 956, no. 1
p. 39

Abstract

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Ly α line profiles are a powerful probe of interstellar medium (ISM) structure, outflow speed, and Lyman-continuum escape fraction. In this paper, we present the Ly α line profiles of the Cosmic Origins Spectrograph (COS) Legacy Archive Spectroscopic SurveY, a sample rich in spectroscopic analogs of reionization-era galaxies. A large fraction of the spectra show a complex profile, consisting of a double-peaked Ly α emission profile in the bottom of a damped, Ly α absorption trough. Such profiles reveal an inhomogeneous ISM. We successfully fit the damped Ly α absorption and the Ly α emission profiles separately, but with complementary covering factors, a surprising result because this approach requires no Ly α exchange between high- N _H _i and low- N _H _i paths. The combined distribution of column densities is qualitatively similar to the bimodal distributions observed in numerical simulations. We find an inverse relation between Ly α peak separation and the [O iii ]/[O ii ] flux ratio, confirming that the covering fraction of Lyman-continuum-thin sightlines increases as the Ly α peak separation decreases. We combine measurements of Ly α peak separation and Ly α red peak asymmetry in a diagnostic diagram, which identifies six Lyman-continuum leakers in the COS Legacy Archive Spectrocopy SurveY (CLASSY) sample. We find a strong correlation between the Ly α trough velocity and the outflow velocity measured from interstellar absorption lines. We argue that greater vignetting of the blueshifted Ly α peak, relative to the redshifted peak, is the source of the well-known discrepancy between shell-model parameters and directly measured outflow properties. The CLASSY sample illustrates how scattering of Ly α photons outside the spectroscopic aperture reshapes Ly α profiles because the distances to these compact starbursts span a large range.

Published in The Astrophysical Journal

ISSN: 1538-4357 (Online)
Publisher: IOP Publishing
Country of publisher: United Kingdom
LCC subjects: Science: Astronomy: Astrophysics
Website: https://iopscience.iop.org/journal/0004-637X

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