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

Year: 2024
Type: article
Abstract: 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.
DOI: 10.3847/1538-4357/ad8158
Authors: 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
Institutions: Rutgers, The State University of New Jersey, Space Telescope Science Institute, University of Minnesota, Carnegie Institution for Science, Princeton University, Carnegie Observatories, Flatiron Institute, University of Groningen, Netherlands Institute for Radio Astronomy, The University of Texas at Austin, Macalester College, RTX (United States), University of Arizona, Raytheon (United States), Indiana University Bloomington, Indiana University
Language: English
Open Access status: gold
Estimated APC paid: $4,499
OpenAlex ID: W4404300259
FWCI: 3.814
Cites: 110
Cited by: 20
Related to: 10