Early Results from GLASS-JWST. XVI. Discovering a Bluer z ∼ 4–7 Universe through UV Slopes

Themiya Nanayakkara; Karl Glazebrook; Colin Jacobs; Andrea Bonchi; Marco Castellano; Adriano Fontana; Charlotte Mason; Emiliano Merlin; Takahiro Morishita; Diego Paris; Michele Trenti; Tommaso Treu; Antonello Calabrò; Kristan Boyett; Marusa Bradac; Nicha Leethochawalit; Danilo Marchesini; Paola Santini; Victoria Strait; Eros Vanzella; Benedetta Vulcani; Xin Wang; Lilian Yang

doi:10.3847/2041-8213/acbfb9

The Astrophysical Journal Letters (Jan 2023)

Early Results from GLASS-JWST. XVI. Discovering a Bluer z ∼ 4–7 Universe through UV Slopes

Themiya Nanayakkara,
Karl Glazebrook,
Colin Jacobs,
Andrea Bonchi,
Marco Castellano,
Adriano Fontana,
Charlotte Mason,
Emiliano Merlin,
Takahiro Morishita,
Diego Paris,
Michele Trenti,
Tommaso Treu,
Antonello Calabrò,
Kristan Boyett,
Marusa Bradac,
Nicha Leethochawalit,
Danilo Marchesini,
Paola Santini,
Victoria Strait,
Eros Vanzella,
Benedetta Vulcani,
Xin Wang,
Lilian Yang

Affiliations

Themiya Nanayakkara: ORCiD; Centre for Astrophysics and Supercomputing, Swinburne University of Technology , PO Box 218, Hawthorn, VIC 3122, Australia ; [email protected]
Karl Glazebrook: ORCiD; Centre for Astrophysics and Supercomputing, Swinburne University of Technology , PO Box 218, Hawthorn, VIC 3122, Australia ; [email protected]
Colin Jacobs: ORCiD; Centre for Astrophysics and Supercomputing, Swinburne University of Technology , PO Box 218, Hawthorn, VIC 3122, Australia ; [email protected]
Andrea Bonchi: Space Science Data Center , Italian Space Agency, via del Politecnico, I-00133, Roma, Italy
Marco Castellano: ORCiD; INAF—Osservatorio Astronomico di Roma , via di Frascati 33, I-00078 Monte Porzio Catone, Italy
Adriano Fontana: ORCiD; INAF—Osservatorio Astronomico di Roma , via di Frascati 33, I-00078 Monte Porzio Catone, Italy
Charlotte Mason: ORCiD; Cosmic Dawn Center (DAWN) , Denmark; Niels Bohr Institute, University of Copenhagen , Jagtvej 128, DK-2200 København N, Denmark
Emiliano Merlin: ORCiD; INAF—Osservatorio Astronomico di Roma , via di Frascati 33, I-00078 Monte Porzio Catone, Italy
Takahiro Morishita: ORCiD; IPAC, California Institute of Technology , MC 314-6, 1200 E. California Blvd., Pasadena, CA 91125, USA
Diego Paris: ORCiD; INAF—Osservatorio Astronomico di Roma , via di Frascati 33, I-00078 Monte Porzio Catone, Italy
Michele Trenti: ORCiD; School of Physics, University of Melbourne , Parkville 3010, VIC, Australia; ARC Centre of Excellence for All Sky Astrophysics in 3 Dimensions (ASTRO 3D) , Australia
Tommaso Treu: ORCiD; Department of Physics and Astronomy, University of California , Los Angeles, 430 Portola Plaza, Los Angeles, CA 90095, USA
Antonello Calabrò: ORCiD; INAF Osservatorio Astronomico di Roma , Via di Frascati 33, I-00078 Monte Porzio Catone, Rome, Italy
Kristan Boyett: ORCiD; School of Physics, University of Melbourne , Parkville 3010, VIC, Australia; ARC Centre of Excellence for All Sky Astrophysics in 3 Dimensions (ASTRO 3D) , Australia
Marusa Bradac: ORCiD; University of Ljubljana , Department of Mathematics and Physics, Jadranska ulica 19, SI-1000 Ljubljana, Slovenia; Department of Physics and Astronomy, University of California Davis , 1 Shields Ave., Davis, CA 95616, USA
Nicha Leethochawalit: ORCiD; School of Physics, University of Melbourne , Parkville 3010, VIC, Australia; ARC Centre of Excellence for All Sky Astrophysics in 3 Dimensions (ASTRO 3D) , Australia; National Astronomical Research Institute of Thailand (NARIT) , Mae Rim, Chiang Mai, 50180, Thailand
Danilo Marchesini: ORCiD; Department of Physics and Astronomy, Tufts University , 574 Boston Ave., Medford, MA 02155, USA
Paola Santini: ORCiD; INAF Osservatorio Astronomico di Roma , Via di Frascati 33, I-00078 Monte Porzio Catone, Rome, Italy
Victoria Strait: ORCiD; Cosmic Dawn Center (DAWN) , Denmark; Niels Bohr Institute, University of Copenhagen , Jagtvej 128, DK-2200 København N, Denmark
Eros Vanzella: ORCiD; INAF—OAS , Osservatorio di Astrofisica e Scienza dello Spazio di Bologna, via Gobetti 93/3, I-40129 Bologna, Italy
Benedetta Vulcani: ORCiD; INAF Osservatorio Astronomico di Padova , vicolo dell’Osservatorio 5, I-35122 Padova, Italy
Xin Wang: ORCiD; Infrared Processing and Analysis Center , Caltech, 1200 E. California Blvd., Pasadena, CA 91125, USA
Lilian Yang: ORCiD; Kavli Institute for the Physics and Mathematics of the Universe, The University of Tokyo , Kashiwa, 277-8583 Japan

DOI: https://doi.org/10.3847/2041-8213/acbfb9
Journal volume & issue: Vol. 947, no. 2
p. L26

Abstract

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We use the GLASS-JWST Early Release Science NIRCam parallel observations to provide a first view of the UV continuum properties of NIRCam/F444W selected galaxies at 4 99% of the galaxies are blue star-forming galaxies with very low levels of dust ( Av _β ∼ 0.01 ± 0.33). We find no statistically significant correlation for UV slope with redshift or UV magnitude. However, we find that in general galaxies at higher redshifts and fainter UV magnitudes have steeper UV slopes. We find a statistically significant correlation for UV slope with stellar mass, with galaxies with higher stellar mass showing shallower UV slopes. Individual fits to some of our galaxies reach the bluest UV slopes of β ∼ −3.1 allowed by stellar population models used in this analysis. Therefore, it is likely that stellar population models with a higher amount of Lyman continuum leakage, active galactic nucleus effects, and/or Population III contributions are required to accurately reproduce the rest-UV and optical properties of some of our bluest galaxies. This dust-free early view confirms that our current cosmological understanding of gradual mass + dust buildup of galaxies with cosmic time is largely accurate to describe the ∼0.7–1.5 Gyr age window of the universe. The abundance of a large population of UV faint dust-poor systems may point to a dominance of low-mass galaxies at z > 6 playing a vital role in cosmic reionization.

Published in The Astrophysical Journal Letters

ISSN: 2041-8205 (Print); 2041-8213 (Online)
Publisher: IOP Publishing
Country of publisher: United Kingdom
LCC subjects: Science: Astronomy: Astrophysics
Website: https://iopscience.iop.org/journal/2041-8205

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