The Ancient Star Formation History of the Extremely Low-mass Galaxy Leo P: An Emerging Trend of a Post-reionization Pause in Star Formation

Kristen B. W. McQuinn; Max J. B. Newman; Evan D. Skillman; O. Grace Telford; Alyson Brooks; Elizabeth A. K. Adams; Danielle A. Berg; Martha L. Boyer; John M. Cannon; Andrew E. Dolphin; Anthony J. Pahl; Katherine L. Rhode; John J. Salzer; Roger E. Cohen; Steve R. Goldman

doi:10.3847/1538-4357/ad8158

The Astrophysical Journal (Jan 2024)

The Ancient Star Formation History of the Extremely Low-mass Galaxy Leo P: An Emerging Trend of a Post-reionization Pause in Star Formation

Kristen B. W. McQuinn,
Max J. B. Newman,
Evan D. Skillman,
O. Grace Telford,
Alyson Brooks,
Elizabeth A. K. Adams,
Danielle A. Berg,
Martha L. Boyer,
John M. Cannon,
Andrew E. Dolphin,
Anthony J. Pahl,
Katherine L. Rhode,
John J. Salzer,
Roger E. Cohen,
Steve R. Goldman

Affiliations

Kristen B. W. McQuinn: ORCiD; Department of Physics and Astronomy, Rutgers, The State University of New Jersey , 136 Frelinghuysen Rd, Piscataway, NJ 08854, USA ; [email protected]; Space Telescope Science Institute , 3700 San Martin Drive, Baltimore, MD 21218, USA
Max J. B. Newman: ORCiD; Department of Physics and Astronomy, Rutgers, The State University of New Jersey , 136 Frelinghuysen Rd, Piscataway, NJ 08854, USA ; [email protected]
Evan D. Skillman: ORCiD; Minnesota Institute for Astrophysics, School of Physics and Astronomy, University of Minnesota , 116 Church Street, S.E., Minneapolis, MN 55455, USA
O. Grace Telford: ORCiD; Department of Physics and Astronomy, Rutgers, The State University of New Jersey , 136 Frelinghuysen Rd, Piscataway, NJ 08854, USA ; [email protected]; Department of Astrophysical Sciences, Princeton University , 4 Ivy Lane, Princeton, NJ 08544, USA; The Observatories of the Carnegie Institution for Science , 813 Santa Barbara Street, Pasadena, CA 91101, USA
Alyson Brooks: ORCiD; Department of Physics and Astronomy, Rutgers, The State University of New Jersey , 136 Frelinghuysen Rd, Piscataway, NJ 08854, USA ; [email protected]; Center for Computational Astrophysics, Flatiron Institute , 162 Fifth Ave, New York, NY 10010, USA
Elizabeth A. K. Adams: ORCiD; ASTRON, The Netherlands Institute for Radio Astronomy , Oude Hoogeveensedijk 4, 7991 PD, Dwingeloo, The Netherlands; Kapteyn Astronomical Institute, University of Groningen , Postbus 800, 9700 AV Groningen, The Netherlands
Danielle A. Berg: ORCiD; Department of Astronomy, The University of Texas at Austin , 2515 Speedway, Stop C1400, Austin, TX 78712, USA
Martha L. Boyer: ORCiD; Space Telescope Science Institute , 3700 San Martin Drive, Baltimore, MD 21218, USA
John M. Cannon: ORCiD; Department of Physics and Astronomy, Macalester College , 1600 Grand Avenue, Saint Paul, MN 55105, USA
Andrew E. Dolphin: ORCiD; Raytheon , 1151 E. Hermans Road, Tucson, AZ 85756, USA; University of Arizona , Steward Observatory, 933 North Cherry Avenue, Tucson, AZ 85721, USA
Anthony J. Pahl: ORCiD; The Observatories of the Carnegie Institution for Science , 813 Santa Barbara Street, Pasadena, CA 91101, USA
Katherine L. Rhode: ORCiD; Department of Astronomy, Indiana University , 727 East Third Street, Bloomington, IN 47405, USA
John J. Salzer: ORCiD; Department of Astronomy, Indiana University , 727 East Third Street, Bloomington, IN 47405, USA
Roger E. Cohen: ORCiD; Department of Physics and Astronomy, Rutgers, The State University of New Jersey , 136 Frelinghuysen Rd, Piscataway, NJ 08854, USA ; [email protected]
Steve R. Goldman: ORCiD; Space Telescope Science Institute , 3700 San Martin Drive, Baltimore, MD 21218, USA

DOI: https://doi.org/10.3847/1538-4357/ad8158
Journal volume & issue: Vol. 976, no. 1
p. 60

Abstract

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Isolated, low-mass galaxies provide the opportunity to assess the impact of reionization on their star formation histories (SFHs) without the ambiguity of environmental processes associated with massive host galaxies. There are very few isolated, low-mass galaxies that are close enough to determine their SFHs from resolved star photometry reaching below the oldest main-sequence turnoff. The James Webb Space Telescope (JWST) has increased the volume for which this is possible, and here we report on JWST observations of the low-mass, isolated galaxy Leo P. From NIRCam imaging in F090W, F150W, and F277W, we derive an SFH that shows early star formation followed by a pause subsequent to the Epoch of Reionization, which is then later followed by a reignition of star formation. This is very similar to the SFHs from previous studies of other dwarf galaxies in the “transition zone” between quenched very-low-mass galaxies and the more massive galaxies that show no evidence of the impact of reionization on their SFHs; this pattern is rarely produced in simulations of SFHs. The lifetime SFH reveals that Leo P’s stellar mass at the Epoch of Reionization was in the range that is normally associated with being totally quenched. The extended pause in star formation from z ∼ 5 to 1 has important implications for the contribution of low-mass galaxies to the ultraviolet photon budget at intermediate redshifts. We also demonstrate that, due to higher sensitivity and angular resolution, observing in two NIRCam short-wavelength filters is superior to observing in a combination of a short- and a long-wavelength filter.

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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