The Astrophysical Journal (Jan 2025)
Relationships between Polycyclic Aromatic Hydrocarbons, Small Dust Grains, H2, and H i in Local Group Dwarf Galaxies NGC 6822 and WLM Using JWST, ALMA, and the VLA
- Ryan Chown,
- Adam K. Leroy,
- Alberto D. Bolatto,
- Jérémy Chastenet,
- Simon C. O. Glover,
- Rémy Indebetouw,
- Eric W. Koch,
- Jennifer Donovan Meyer,
- Nickolas M. Pingel,
- Erik Rosolowsky,
- Karin Sandstrom,
- Jessica Sutter,
- Elizabeth Tarantino,
- Frank Bigiel,
- Médéric Boquien,
- I-Da Chiang,
- Daniel A. Dale,
- Julianne J. Dalcanton,
- Oleg V. Egorov,
- Cosima Eibensteiner,
- Kathryn Grasha,
- Hamid Hassani,
- Hao He,
- Jaeyeon Kim,
- Sharon Meidt,
- Debosmita Pathak,
- Sumit K. Sarbadhicary,
- Snezana Stanimirovic,
- Vicente Villanueva,
- Thomas G. Williams
Affiliations
- Ryan Chown
- ORCiD
- Department of Astronomy, The Ohio State University , 140 West 18th Avenue, Columbus, OH 43210, USA ; [email protected]
- Adam K. Leroy
- ORCiD
- Department of Astronomy, The Ohio State University , 140 West 18th Avenue, Columbus, OH 43210, USA ; [email protected]; Center for Cosmology and Astroparticle Physics (CCAPP) , 191 West Woodruff Avenue, Columbus, OH 43210, USA
- Alberto D. Bolatto
- ORCiD
- Department of Astronomy and Joint Space-Science Institute, University of Maryland , College Park, MD 20742, USA
- Jérémy Chastenet
- ORCiD
- Sterrenkundig Observatorium, Universiteit Gent , Krijgslaan 281 S9, B-9000 Gent, Belgium
- Simon C. O. Glover
- ORCiD
- Universität Heidelberg , Zentrum für Astronomie, Institut für Theoretische Astrophysik, Albert-Ueberle-Str 2, D-69120 Heidelberg, Germany
- Rémy Indebetouw
- ORCiD
- Department of Astronomy, University of Virginia , Charlottesville, VA, USA; National Radio Astronomy Observatory , Charlottesville, VA, USA
- Eric W. Koch
- ORCiD
- Center for Astrophysics—Harvard & Smithsonian , 60 Garden Street, Cambridge, MA 02138, USA
- Jennifer Donovan Meyer
- ORCiD
- National Radio Astronomy Observatory , Charlottesville, VA, USA
- Nickolas M. Pingel
- ORCiD
- University of Wisconsin-Madison , Department of Astronomy, 475 N Charter St, Madison, WI 53703, USA
- Erik Rosolowsky
- ORCiD
- Department of Physics, University of Alberta , 4-183 CCIS, Edmonton, Alberta, T6G 2E1, Canada
- Karin Sandstrom
- ORCiD
- Department of Astronomy & Astrophysics, University of California , San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA
- Jessica Sutter
- ORCiD
- Whitman College , 345 Boyer Avenue, Walla Walla, WA 99362, USA
- Elizabeth Tarantino
- ORCiD
- Space Telescope Science Institute , 3700 San Martin Drive, Baltimore, MD 21218, USA
- Frank Bigiel
- ORCiD
- Argelander-Institut für Astronomie, Universität Bonn , Auf dem Hügel 71, 53121 Bonn, Germany
- Médéric Boquien
- ORCiD
- Université Côte d’Azur , Observatoire de la Côte d’Azur, CNRS, Laboratoire Lagrange, 06000, Nice, France
- I-Da Chiang
- ORCiD
- Institute of Astronomy and Astrophysics , Academia Sinica, No. 1, Sec. 4, Roosevelt Road, Taipei 106216, Taiwan
- Daniel A. Dale
- ORCiD
- Department of Physics and Astronomy, University of Wyoming , Laramie, WY 82071, USA
- Julianne J. Dalcanton
- ORCiD
- Center for Computational Astrophysics, Flatiron Institute , 162 Fifth Ave, New York, NY 10010, USA; Department of Astronomy, University of Washington , Seattle, WA 98195, USA
- Oleg V. Egorov
- ORCiD
- Astronomisches Rechen-Institut, Zentrum für Astronomie der Universität Heidelberg , Mönchhofstr. 12–14, D-69120 Heidelberg, Germany
- Cosima Eibensteiner
- ORCiD
- National Radio Astronomy Observatory , Charlottesville, VA, USA
- Kathryn Grasha
- ORCiD
- Research School of Astronomy and Astrophysics, Australian National University , Canberra, ACT 2611, Australia
- Hamid Hassani
- ORCiD
- Department of Physics, University of Alberta , 4-183 CCIS, Edmonton, Alberta, T6G 2E1, Canada
- Hao He
- ORCiD
- Argelander-Institut für Astronomie, Universität Bonn , Auf dem Hügel 71, 53121 Bonn, Germany
- Jaeyeon Kim
- ORCiD
- Kavli Institute for Particle Astrophysics & Cosmology (KIPAC), Stanford University , CA 94305, USA
- Sharon Meidt
- ORCiD
- Sterrenkundig Observatorium, Universiteit Gent , Krijgslaan 281 S9, B-9000 Gent, Belgium
- Debosmita Pathak
- ORCiD
- Department of Astronomy, The Ohio State University , 140 West 18th Avenue, Columbus, OH 43210, USA ; [email protected]; Center for Cosmology and Astroparticle Physics (CCAPP) , 191 West Woodruff Avenue, Columbus, OH 43210, USA
- Sumit K. Sarbadhicary
- ORCiD
- Department of Astronomy, The Ohio State University , 140 West 18th Avenue, Columbus, OH 43210, USA ; [email protected]; Center for Cosmology and Astroparticle Physics (CCAPP) , 191 West Woodruff Avenue, Columbus, OH 43210, USA; Department of Physics, The Ohio State University , Columbus, OH 43210, USA
- Snezana Stanimirovic
- ORCiD
- University of Wisconsin-Madison , Department of Astronomy, 475 N Charter St, Madison, WI 53703, USA
- Vicente Villanueva
- ORCiD
- Departamento de Astronomía, Universidad de Concepción , Barrio Universitario, Concepción, Chile
- Thomas G. Williams
- ORCiD
- Sub-department of Astrophysics, Department of Physics, University of Oxford , Keble Road, Oxford OX1 3RH, UK
- DOI
- https://doi.org/10.3847/1538-4357/add73a
- Journal volume & issue
-
Vol. 987,
no. 1
p. 91
Abstract
We present 0.6–3.2 pc resolution mid-infrared (MIR) JWST images at 7.7 μ m (F770W) and 21 μ m (F2100W) covering the main star-forming regions of two of the closest star-forming low-metallicity dwarf galaxies, NGC 6822 and Wolf–Lundmark–Melotte (WLM). The images of NGC 6822 reveal filaments, edge-brightened bubbles, diffuse emission, and a plethora of point sources. By contrast, most of the MIR emission in WLM is pointlike, with a small amount of extended emission. Compared to solar-metallicity galaxies, the ratio of 7.7 μ m intensity ( ${I}_{\nu }^{{\rm{F770W}}}$ ), tracing polycyclic aromatic hydrocarbons (PAHs), to 21 μ m intensity ( ${I}_{\nu }^{{\rm{F2100W}}}$ ), tracing small, warm dust grain emission, is suppressed in these low-metallicity dwarfs. Using Atacama Large Millimeter/submillimeter Array CO(2–1) observations, we find that detected CO intensity versus ${I}_{\nu }^{{\rm{F770W}}}$ at ≈2 pc resolution in dwarfs follows a similar relationship to that at solar metallicity and lower resolution, while the CO versus ${I}_{\nu }^{{\rm{F2100W}}}$ relationship in dwarfs lies significantly below that derived from solar-metallicity galaxies at lower resolution, suggesting more pronounced destruction of CO molecules at low metallicity. Finally, adding in Local Group L-Band Survey 21 cm H i observations from the Very Large Array, we find that ${I}_{\nu }^{{\rm{F2100W}}}$ and ${I}_{\nu }^{{\rm{F770W}}}$ versus total gas ratios are suppressed in NGC 6822 and WLM compared to solar-metallicity galaxies. In agreement with dust models, the level of suppression appears to be at least partly accounted for by the reduced galaxy-averaged dust-to-gas and PAH-to-dust mass ratios in the dwarfs. Remaining differences are likely due to spatial variations in dust model parameters, which should be an exciting direction for future work in local dwarf galaxies.
Keywords
- Dwarf irregular galaxies
- Polycyclic aromatic hydrocarbons
- Interstellar dust
- Dust nebulae
- Molecular gas
- Interstellar atomic gas
