The Star Formation in Radio Survey: Adding 90 GHz Data to 3–33 GHz Observations of Star-forming Regions in Nearby Galaxies
We present 90 GHz continuum imaging of 119 star-forming regions in 30 nearby galaxies observed with MUSTANG-2 on the Robert C. Byrd Green Bank Telescope as part of the Star Formation in Radio Survey. The 90 GHz data were combined with 3, 15, and 33 GHz data taken previously by the Karl G. Jansky Ver...
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2025-01-01
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| Online Access: | https://doi.org/10.3847/1538-4357/ade436 |
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| author | Anna Dignan Eric J. Murphy Brian Mason Cosima Eibensteiner Brandon S. Hensley Eric F. Jiménez-Andrade Sean T. Linden Simon R. Dicker Dillon Z. Dong Emmanuel Momjian Charles E. Romero Eva Schinnerer Jean L. Turner |
| author_facet | Anna Dignan Eric J. Murphy Brian Mason Cosima Eibensteiner Brandon S. Hensley Eric F. Jiménez-Andrade Sean T. Linden Simon R. Dicker Dillon Z. Dong Emmanuel Momjian Charles E. Romero Eva Schinnerer Jean L. Turner |
| author_sort | Anna Dignan |
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| description | We present 90 GHz continuum imaging of 119 star-forming regions in 30 nearby galaxies observed with MUSTANG-2 on the Robert C. Byrd Green Bank Telescope as part of the Star Formation in Radio Survey. The 90 GHz data were combined with 3, 15, and 33 GHz data taken previously by the Karl G. Jansky Very Large Array to decompose radio spectra on ≈0.8 kpc scales into their synchrotron, free–free, and thermal dust emission components. This was done using three scenarios: (i) a power-law fit from 3 to 33 GHz, (ii) Markov Chain Monte Carlo (MCMC) fitting from 3 to 90 GHz with a thermal dust component, and (iii) MCMC fitting from 3 to 33 GHz without a thermal dust component. For these cases, we find a median thermal (free–free) emission fraction at 33 GHz of (i) 88% ± 2% with a scatter of 17%, (ii) 76% ± 3% with a scatter of 25%, and (iii) 84% ± 2% with a scatter of 18%. From this we conclude that, on average, free–free emission, not thermal dust, remains the dominant emission component at 33 GHz. While scenario (ii) yields a thermal fraction that is ≈10% larger than scenario (iii), this difference decreases to ≈5% after active galactic nuclei are removed. Consequently, star formation rates measured with thermal fractions at 33 GHz are only mildly biased high without 90 GHz data for the spectral decomposition. Furthermore, a power-law fit of data from 3 to 33 GHz still provides a reliable estimate of the free–free emission at 33 GHz. |
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| institution | Kabale University |
| issn | 1538-4357 |
| language | English |
| publishDate | 2025-01-01 |
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| series | The Astrophysical Journal |
| spelling | doaj-art-aea07e4ef97c4d61b2baff88bad8f7ff2025-08-20T03:55:48ZengIOP PublishingThe Astrophysical Journal1538-43572025-01-01988221610.3847/1538-4357/ade436The Star Formation in Radio Survey: Adding 90 GHz Data to 3–33 GHz Observations of Star-forming Regions in Nearby GalaxiesAnna Dignan0https://orcid.org/0009-0000-8877-135XEric J. Murphy1https://orcid.org/0000-0001-7089-7325Brian Mason2https://orcid.org/0000-0002-8472-836XCosima Eibensteiner3https://orcid.org/0000-0002-1185-2810Brandon S. Hensley4https://orcid.org/0000-0001-7449-4638Eric F. Jiménez-Andrade5https://orcid.org/0000-0002-2640-5917Sean T. Linden6https://orcid.org/0000-0002-1000-6081Simon R. Dicker7https://orcid.org/0000-0002-1940-4289Dillon Z. Dong8https://orcid.org/0000-0001-9584-2531Emmanuel Momjian9https://orcid.org/0000-0003-3168-5922Charles E. Romero10https://orcid.org/0000-0001-5725-0359Eva Schinnerer11https://orcid.org/0000-0002-3933-7677Jean L. Turner12https://orcid.org/0000-0003-4625-2951National Radio Astronomy Observatory , 520 Edgemont Road, Charlottesville, VA 22903, USA; Department of Astronomy, University of Virginia , Charlottesville, VA 22904, USANational Radio Astronomy Observatory , 520 Edgemont Road, Charlottesville, VA 22903, USANational Radio Astronomy Observatory , 520 Edgemont Road, Charlottesville, VA 22903, USANational Radio Astronomy Observatory , 520 Edgemont Road, Charlottesville, VA 22903, USAJet Propulsion Laboratory, California Institute of Technology , 4800 Oak Grove Drive, Pasadena, CA 91109, USAInstituto de Radioastronomía y Astrofísica, Universidad Nacional Autónoma de México , Antigua Carretera a Pátzcuaro # 8701, Ex-Hda. San José de la Huerta, Morelia, Michoacán, C.P. 58089, MéxicoSteward Observatory, University of Arizona , 933 N. Cherry Avenue, Tucson, AZ 85721, USADepartment of Physics and Astronomy, University of Pennsylvania , 209 S. 33rd St., Philadelphia, PA 19014, USANational Radio Astronomy Observatory , P.O. Box O, 1011 Lopezville Road, Socorro, NM 87801, USANational Radio Astronomy Observatory , P.O. Box O, 1011 Lopezville Road, Socorro, NM 87801, USADepartment of Physics and Astronomy, University of Pennsylvania , 209 S. 33rd St., Philadelphia, PA 19014, USAMax Planck Institute for Astronomy , Königstuhl 17, 69117, Heidelberg, GermanyDepartment of Physics and Astronomy , UCLA, Los Angeles, CA 90095, USAWe present 90 GHz continuum imaging of 119 star-forming regions in 30 nearby galaxies observed with MUSTANG-2 on the Robert C. Byrd Green Bank Telescope as part of the Star Formation in Radio Survey. The 90 GHz data were combined with 3, 15, and 33 GHz data taken previously by the Karl G. Jansky Very Large Array to decompose radio spectra on ≈0.8 kpc scales into their synchrotron, free–free, and thermal dust emission components. This was done using three scenarios: (i) a power-law fit from 3 to 33 GHz, (ii) Markov Chain Monte Carlo (MCMC) fitting from 3 to 90 GHz with a thermal dust component, and (iii) MCMC fitting from 3 to 33 GHz without a thermal dust component. For these cases, we find a median thermal (free–free) emission fraction at 33 GHz of (i) 88% ± 2% with a scatter of 17%, (ii) 76% ± 3% with a scatter of 25%, and (iii) 84% ± 2% with a scatter of 18%. From this we conclude that, on average, free–free emission, not thermal dust, remains the dominant emission component at 33 GHz. While scenario (ii) yields a thermal fraction that is ≈10% larger than scenario (iii), this difference decreases to ≈5% after active galactic nuclei are removed. Consequently, star formation rates measured with thermal fractions at 33 GHz are only mildly biased high without 90 GHz data for the spectral decomposition. Furthermore, a power-law fit of data from 3 to 33 GHz still provides a reliable estimate of the free–free emission at 33 GHz.https://doi.org/10.3847/1538-4357/ade436Star formationH II regionsRadio continuum emissionStar forming regionsRadio interferometryRadio astronomy |
| spellingShingle | Anna Dignan Eric J. Murphy Brian Mason Cosima Eibensteiner Brandon S. Hensley Eric F. Jiménez-Andrade Sean T. Linden Simon R. Dicker Dillon Z. Dong Emmanuel Momjian Charles E. Romero Eva Schinnerer Jean L. Turner The Star Formation in Radio Survey: Adding 90 GHz Data to 3–33 GHz Observations of Star-forming Regions in Nearby Galaxies The Astrophysical Journal Star formation H II regions Radio continuum emission Star forming regions Radio interferometry Radio astronomy |
| title | The Star Formation in Radio Survey: Adding 90 GHz Data to 3–33 GHz Observations of Star-forming Regions in Nearby Galaxies |
| title_full | The Star Formation in Radio Survey: Adding 90 GHz Data to 3–33 GHz Observations of Star-forming Regions in Nearby Galaxies |
| title_fullStr | The Star Formation in Radio Survey: Adding 90 GHz Data to 3–33 GHz Observations of Star-forming Regions in Nearby Galaxies |
| title_full_unstemmed | The Star Formation in Radio Survey: Adding 90 GHz Data to 3–33 GHz Observations of Star-forming Regions in Nearby Galaxies |
| title_short | The Star Formation in Radio Survey: Adding 90 GHz Data to 3–33 GHz Observations of Star-forming Regions in Nearby Galaxies |
| title_sort | star formation in radio survey adding 90 ghz data to 3 33 ghz observations of star forming regions in nearby galaxies |
| topic | Star formation H II regions Radio continuum emission Star forming regions Radio interferometry Radio astronomy |
| url | https://doi.org/10.3847/1538-4357/ade436 |
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