Journal article
The nature of infrared emission in the local group dwarf galaxy NGC 6822 as revealed by spitzer
The Astrophysical journal, Vol.652(2), pp.1170-1187
12/01/2006
DOI: 10.1086/508341
Abstract
We present Spitzer imaging of the metal-deficient (Z ≃ 30% Z☉) Local Group dwarf galaxy NGC 6822. On spatial scales of ~130 pc, we study the nature of IR, Hα, H I, and radio continuum emission. Nebular emission strength correlates with IR surface brightness; however, roughly half of the IR emission is associated with diffuse regions not luminous at Hα (as found in previous studies). The global ratio of dust to H I gas in the ISM, while uncertain at the factor of ~2 level, is ~25 times lower than the global values derived for spiral galaxies using similar modeling techniques; localized ratios of dust to H I gas are about a factor of 5 higher than the global value in NGC 6822. There are strong variations (factors of ~10) in the relative ratios of Hα and IR flux throughout the central disk; the low dust content of NGC 6822 is likely responsible for the different Hα/IR ratios compared to those found in more metal-rich environments. The Hα and IR emission is associated with high column density (≳1021 cm-2) neutral gas. Increases in IR surface brightness appear to be affected by both increased radiation field strength and increased local gas density. Individual regions and the galaxy as a whole fall within the observed scatter of recent high-resolution studies of the radio-far-IR correlation in nearby spiral galaxies; this is likely the result of depleted radio and far-IR emission strengths in the ISM of this dwarf galaxy.
Details
- Title: Subtitle
- The nature of infrared emission in the local group dwarf galaxy NGC 6822 as revealed by spitzer
- Creators
- John M Cannon - Wesleyan UniversityFabian Walter - Max Planck Institute for AstronomyHélène Roussel - Max Planck Institute for AstronomyCaroline Bot - California Institute of TechnologyBrent A Buckalew - California Institute of TechnologyDaniel A Dale - University of WyomingW. J. G DE BLOK - Mount Stromlo ObservatoryKarl D Gordon - University of ArizonaDavid J Hollenbach - Ames Research CenterThomas H Jarrett - California Institute of TechnologyMartin J Meyer - Space Telescope Science InstituteEric J Murphy - Yale UniversityLee Armus - California Institute of TechnologyKartik Sheth - California Institute of TechnologyMichele D Thornley - Bucknell UniversityGeorge J Bendo - University of ArizonaDaniela Calzetti - Space Telescope Science InstituteBruce T Draine - Princeton UniversityCharles W Engelbracht - University of ArizonaGeorge Helou - California Institute of TechnologyRobert C Kennicutt - University of CambridgeClaus Leitherer - Space Telescope Science Institute
- Resource Type
- Journal article
- Publication Details
- The Astrophysical journal, Vol.652(2), pp.1170-1187
- Publisher
- University of Chicago Press
- DOI
- 10.1086/508341
- ISSN
- 0004-637X
- eISSN
- 1538-4357
- Language
- English
- Date published
- 12/01/2006
- Academic Unit
- Physics and Astronomy
- Record Identifier
- 9984627343302771
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