Direct far-infrared metal abundances (FIRA): I. M101
Accurately determining gas-phase metal abundances within galaxies is critical as metals strongly affect the physics of the interstellar medium. To date, the vast majority of widely used gas-phase abundance indicators rely on emission from bright optical lines, whose emissivities are highly sensitive...
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| Main Authors: | , , , , , , , , , , , , , , |
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| Format: | Article (Journal) |
| Language: | English |
| Published: |
2022 February 4
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| In: |
The astrophysical journal
Year: 2022, Volume: 925, Issue: 2, Pages: 1-22 |
| ISSN: | 1538-4357 |
| DOI: | 10.3847/1538-4357/ac3b4f |
| Online Access: | Verlag, lizenzpflichtig, Volltext: https://doi.org/10.3847/1538-4357/ac3b4f
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| Author Notes: | C. Lamarche, J.D. Smith, K. Kreckel, S.T. Linden, N.S.J. Rogers, E. Skillman, D. Berg, E. Murphy, R. Pogge, G.P. Donnelly, R. Kennicutt, A. Bolatto, K. Croxall, B. Groves, and C. Ferkinhoff |
| Summary: | Accurately determining gas-phase metal abundances within galaxies is critical as metals strongly affect the physics of the interstellar medium. To date, the vast majority of widely used gas-phase abundance indicators rely on emission from bright optical lines, whose emissivities are highly sensitive to the electron temperature. Alternatively, direct-abundance methods exist that measure the temperature of the emitting gas directly, though these methods usually require challenging observations of highly excited auroral lines. Low-lying far-infrared (FIR) fine structure lines are largely insensitive to electron temperature and thus provide an attractive alternative to optically derived abundances. Here, we introduce the far-infrared abundance (FIRA) project, which employs these FIR transitions, together with both radio free-free emission and hydrogen recombination lines, to derive direct, absolute gas-phase oxygen abundances. Our first target is M101, a nearby spiral galaxy with a relatively steep abundance gradient. Our results are consistent with the O++ electron temperatures and absolute oxygen abundances derived using optical direct-abundance methods by the CHemical Abundance Of Spirals (CHAOS) program, with a small difference (∼1.5σ) in the radial abundance gradients derived by the FIR/free-free-normalized versus CHAOS/direct-abundance techniques. This initial result demonstrates the validity of the FIRA methodology—with the promise of determining absolute metal abundances within dusty star-forming galaxies, both locally and at high redshift. |
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| Item Description: | Gesehen am 20.04.2022 |
| Physical Description: | Online Resource |
| ISSN: | 1538-4357 |
| DOI: | 10.3847/1538-4357/ac3b4f |