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Metal Abundances across Cosmic Time (MACT) Survey. III – The relationship between stellar mass and star formation rate in extremely low-mass galaxies

Shin, Kaitlyn and Ly, Chun and Malkan, Matthew A. and Malhotra, Sangeeta and de los Reyes, Mithi and Rhoads, James E. (2021) Metal Abundances across Cosmic Time (MACT) Survey. III – The relationship between stellar mass and star formation rate in extremely low-mass galaxies. Monthly Notices of the Royal Astronomical Society, 501 (2). pp. 2231-2249. ISSN 0035-8711.

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Extragalactic studies have demonstrated that there is a moderately tight (≈0.3 dex) relationship between galaxy stellar mass (M_⋆) and star formation rate (SFR) that holds for star-forming galaxies at M_⋆ ∼ 3 × 10⁸–10¹¹ M_⊙, i.e. the ‘star formation main sequence’. However, it has yet to be determined whether such a relationship extends to even lower mass galaxies, particularly at intermediate or higher redshifts. We present new results using observations for 714 narrow-band H α-selected galaxies with stellar masses between 10⁶ and 10¹⁰ M_⊙ (average of 10^(8.2) M_⊙) at z ≈ 0.07–0.5. These galaxies have sensitive ultraviolet (UV) to near-infrared photometric measurements and optical spectroscopy. The latter allows us to correct our H α SFRs for dust attenuation using Balmer decrements. Our study reveals that: (1) for low-SFR galaxies, our H α SFRs systematically underpredict compared to far-UV measurements, consistent with other studies; (2) at a given stellar mass (≈10⁸ M⊙), log (specific SFR) evolves as A log (1 + z) with A = 5.26 ± 0.75, and on average, specific SFR increases with decreasing stellar mass; (3) the SFR–M⋆ relation holds for galaxies down to ∼10⁶ M_⊙ (∼1.5 dex below previous studies), and over lookback times of up to 5 Gyr, follows a redshift-dependent relation of log (SFR) ∝ α log (M_⋆/M_⊙) + β z with α = 0.60 ± 0.01 and β = 1.86 ± 0.07; and (4) the observed dispersion in the SFR–M⋆ relation at low stellar masses is ≈0.3 dex. Accounting for survey selection effects using simulated galaxies, we estimate that the true dispersion is ≈0.5 dex.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Shin, Kaitlyn0000-0002-6823-2073
Ly, Chun0000-0002-4245-2318
Malkan, Matthew A.0000-0001-6919-1237
Malhotra, Sangeeta0000-0002-9226-5350
de los Reyes, Mithi000-0002-4739-046X
Rhoads, James E.0000-0002-1501-454X
Additional Information:© 2020 The Author(s). Published by Oxford University Press on behalf of Royal Astronomical Society. This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model ( Accepted 2020 October 20. Received 2020 September 16; in original form 2019 October 23. Published: 31 October 2020. We thank the anonymous referee for helpful feedback that improved the quality of this paper. This work was supported by a NASA Keck PI Data Award, administered by the NASA Exoplanet Science Institute. Data presented herein were obtained at the W. M. Keck Observatory from telescope time allocated to the National Aeronautics and Space Administration through the agency’s scientific partnership with the California Institute of Technology and the University of California. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation. The authors wish to recognize and acknowledge the very significant cultural role and reverence that the summit of Mauna Kea has always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain. Hectospec observations reported here were obtained at the MMT Observatory, a joint facility of the Smithsonian Institution and the University of Arizona. A subset of the MMT telescope time was granted by NOAO, through the NSF-funded Telescope System Instrumentation Program (TSIP). We thank Perry Berlind, Michael Calkins, and Ben Weiner for acquisition of the Hectospec data. We thank Nobunari Kashikawa for help in acquisition of the Keck data. We thank Leindert Boogaard for sharing data to compare analyses and helpful private communications. We also thank Bruce Macintosh for his support. We gratefully acknowledge NASA’s support for construction, operation, and science analysis for the GALEX mission. This research made use of the following PYTHON packages: numpy (Oliphant 2006; Harris et al. 2020), scipy (Jones et al. 2001; Virtanen et al. 2020), matplotlib (Hunter 2007), and astropy (Astropy Collaboration 2013, 2018). Data Availability: The data in this article are available upon request to the corresponding author.
Funding AgencyGrant Number
W. M. Keck FoundationUNSPECIFIED
National Oceanic and Atmospheric Administration (NOAA)UNSPECIFIED
Subject Keywords:galaxies: distances and redshifts – galaxies: evolution – galaxies: star formation – dust, extinction – techniques: spectroscopic – techniques: photometric
Issue or Number:2
Record Number:CaltechAUTHORS:20210212-093111892
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Official Citation:Kaitlyn Shin, Chun Ly, Matthew A Malkan, Sangeeta Malhotra, Mithi de los Reyes, James E Rhoads, The Metal Abundances across Cosmic Time (MACT) Survey. III – The relationship between stellar mass and star formation rate in extremely low-mass galaxies, Monthly Notices of the Royal Astronomical Society, Volume 501, Issue 2, February 2021, Pages 2231–2249,
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:108031
Deposited By: Tony Diaz
Deposited On:12 Feb 2021 17:54
Last Modified:12 Feb 2021 17:54

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