A Nonparametric Morphological Analysis of Hα Emission in Bright Dwarfs Using the Merian Survey

Abby Mintz, Jenny E. Greene, Erin Kado-Fong, Shany Danieli, Jiaxuan Li, Yifei Luo, Alexie Leauthaud, Vivienne Baldassare, Song Huang, Annika H.G. Peter, Joy Bhattacharyya, Mingyu Li, Yue Pan

Research output: Contribution to journalArticlepeer-review

Abstract

Using medium-band imaging from the newly released Merian Survey, we conduct a nonparametric morphological analysis of Hα emission maps and stellar continua for a sample of galaxies with 8 ≲ log ( M ⋆ / M ⊙ ) < 10.3 at 0.064 < z < 0.1. We present a novel method for estimating the stellar continuum emission through the Merian Survey’s N708 medium-band filter, which we use to measure Hα emission and produce Hα maps for our sample of galaxies with seven-band Merian photometry and available spectroscopy. We measure nonparametric morphological statistics for the Hα and stellar continuum images, explore how the morphology of the Hα differs from the continuum, and investigate how the parameters evolve with the galaxies’ physical properties. In agreement with previous results for more massive galaxies, we find that the asymmetry of the stellar continuum increases with specific star formation rate (sSFR), and we extend the trend to lower masses, also showing that it holds for the asymmetry of the Hα emission. We find that the lowest-mass galaxies with the highest sSFR have Hα emission that is consistently heterogeneous and compact, while the less active galaxies in this mass range have Hα emission that appears diffuse. At higher masses, our data do not span a sufficient range in sSFR to evaluate whether similar trends apply. We conclude that high sSFRs in low-mass galaxies likely result from dynamical instabilities that compress a galaxy’s molecular gas to a dense region near the center.

Original languageEnglish
Article number273
JournalAstrophysical Journal
Volume974
Issue number2
DOIs
StatePublished - 1 Oct 2024

Funding

FundersFunder number
Mitchell Institute for Fundamental Physics and Astronomy at Texas A&M University
Kavli Institute for Cosmological Physics, University of Chicago
National Astronomical Observatory of Japan
Japan Society for the Promotion of Science
Fundação Carlos Chagas Filho de Amparo à Pesquisa do Estado do Rio de Janeiro
Ohio State University
Higher Education Funding Council for England
Financiadora de Estudos e Projetos
Ministry of Education and Science of Ukraine
Conselho Nacional de Desenvolvimento Científico e Tecnológico
Kavli IPMU
Deutsche Forschungsgemeinschaft
Toray Science Foundation
U.S. Department of Energy
ASIAA
Princeton University
High Energy Accelerator Research Organization
Science and Technology Facilities Council of the United Kingdom
Ministério da Ciência, Tecnologia e Inovação
Japan Science and Technology Agency
National Centre for Supercomputing Applications
Collaborating Institutions in the Dark Energy Survey
Ministry of Education, Culture, Sports, Science and Technology
National Science Foundation2039656
National Natural Science Foundation of China12273015, 2106839, 1007052

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