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 Citations (Scopus)

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)
JournalAstrophysical Journal
Volume652
Issue number2 II
DOIs
StatePublished - Dec 1 2006

Fingerprint

H II regions
spatial resolution
galaxies
high resolution
diffraction
star formation rate
active galactic nuclei
narrowband
extrapolation
calibration
stars

Keywords

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

ASJC Scopus subject areas

  • Space and Planetary Science

Cite this

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). https://doi.org/10.1086/510016

High spatial resolution T-ReCS mid-infrared imaging of luminous infrared galaxies. / Alonso-Herrero, Almudena; Colina, Luis; Packham, Christopher; Díaz-Santos, Tanio; Rieke, George H.; Radomski, James T.; Telesco, Charles M.

In: Astrophysical Journal, Vol. 652, No. 2 II, 01.12.2006.

Research output: Contribution to journalArticle

Alonso-Herrero, A, Colina, L, Packham, C, Díaz-Santos, T, Rieke, GH, Radomski, JT & Telesco, CM 2006, 'High spatial resolution T-ReCS mid-infrared imaging of luminous infrared galaxies', Astrophysical Journal, vol. 652, no. 2 II. https://doi.org/10.1086/510016
Alonso-Herrero A, Colina L, Packham C, Díaz-Santos T, Rieke GH, Radomski JT et al. High spatial resolution T-ReCS mid-infrared imaging of luminous infrared galaxies. Astrophysical Journal. 2006 Dec 1;652(2 II). https://doi.org/10.1086/510016
Alonso-Herrero, Almudena ; Colina, Luis ; Packham, Christopher ; Díaz-Santos, Tanio ; Rieke, George H. ; Radomski, James T. ; Telesco, Charles M. / High spatial resolution T-ReCS mid-infrared imaging of luminous infrared galaxies. In: Astrophysical Journal. 2006 ; Vol. 652, No. 2 II.
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AB - 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.

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