Mon. Not. R. Astron. Soc., 307, 553-576 (1999/August-2)
New 8-13 mu-m spectroscopy of luminous and ultraluminous infrared galaxies.
Abstract (from CDS):
New moderate-resolution mid-infrared spectroscopy at 10µm of 27 infrared galaxies is presented. The galaxies have been chosen from three 60-µm selected and one 12-µm selected complete flux-limited catalogues of galaxies; 17 of these sources have LIR(8-1000µm)≥5x1011L☉. A high-resolution spectrum of the source Arp 299B1 is also presented. Combining these new results with previously published results, a nearly complete 60-µm selected flux-limited subsample, with LIR(8-1000µm)≥1.6x1011L☉, of 25 galaxies is defined. Within this subsample, it is found that the dominant power source of infrared galaxies in the luminosity range 1.6x1011<LIR(8-1000µm)<1012L☉ is massive star formation based on the clear presence of the 11.3-µm aromatic hydrocarbon emission feature in the majority of the spectra. Three of the five ultraluminous infrared galaxies LIR(8-1000µm)≥1012L☉] within this subsample show evidence that an active galactic nucleus provides an energetically important power source based on the detection of silicate absorption in their mid-infrared spectra. The physical basis of a possible anticorrelation between the 11.3-µm feature equivalent width and infrared light to molecular gas mass ratios is discussed.
1999, Royal Astronomical Society