High spatial resolution T-ReCS mid-infrared imaging of luminous infrared galaxies

Almudena Alonso-Herrero, Luis Colina, Christopher Packham, Tanio Díaz-Santos, George H. Rieke, James T. Radomski, Charles M. Telesco

Research output: Contribution to journalArticle

38 Scopus citations

Abstract

We present diffraction-limited (FWHM ∼ 0″.3) Gemini/T-ReCS mid-infrared (MIR; W-band or narrowband at 8.7 μm) imaging of four luminous infrared galaxies (LIRGs) drawn from a representative local sample. The MIR emission in the central few kiloparsecs is strikingly similar to that traced by Paα and generally consists of bright nuclear emission and several compact circumnuclear and/or extranuclear H II regions. The central MIR emission is dominated by these powerful H II regions, consistent with the majority of active galactic nuclei in this local sample of LIRGs contributing a minor part of the MIR emission. The luminous circumnuclear H II regions detected in LIRGs follow the extrapolation of the 8 μm versus Paα relation found for M51 H II knots. The integrated central 3-7 kpc of galaxies, however, present elevated 8 μm/Paα ratios with respect to individual H II regions, similar to the integrated values for star-forming galaxies. Our results show that the diffuse 8 μm emission, not directly related to the ionizing stellar population, can be as luminous as that from the resolved H II regions. Therefore, calibrations of the star formation rate for distant galaxies should be based on the integrated 8 μm emission of nearby galaxies, not that of the H II regions alone.

Original languageEnglish (US)
Pages (from-to)L83-L87
JournalAstrophysical Journal
Volume652
Issue number2 II
DOIs
StatePublished - Dec 1 2006

Keywords

  • Galaxies: Seyfert
  • Galaxies: evolution
  • Galaxies: nuclei
  • Galaxies: structure
  • Infrared: galaxies

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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    Alonso-Herrero, A., Colina, L., Packham, C., Díaz-Santos, T., Rieke, G. H., Radomski, J. T., & Telesco, C. M. (2006). High spatial resolution T-ReCS mid-infrared imaging of luminous infrared galaxies. Astrophysical Journal, 652(2 II), L83-L87. https://doi.org/10.1086/510016