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The Active Nucleus in the Ultraluminous Infrared Galaxy IRAS 08311-2459

T. W. Murphy Jr.·B. T. Soifer·K. Matthews·L. Armus
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Abstract

Near-infrared spectroscopy using the new Palomar Integral Field Spectrograph indicates the presence of an AGN (active galactic nucleus) in the ultraluminous infrared galaxy IRAS 08311-2459. The high-velocity wings of the Paschen-alpha hydrogen recombination line are seen to be spatially unresolved, and with no positional offset between red and blue high velocity emission. The [Si VI] coronal line, with a 167 eV excitation potential, is also spatially unresolved with a velocity width comparable to that of the broad component of the Pa-alpha emission. The low velocity component of the Pa-alpha emission is seen to be rotating, and is extended over about 2 kpc. Molecular hydrogen is also extended, and elongated along the maximum velocity gradient, sharing the same rotation profile as the narrow Pa-alpha emission. The simple picture in agreement with the observations is that of an AGN surrounded by a rotating disk of star formation. These observations lend strength to the usage of [Si VI] as a diagnostic of AGN activity in ultraluminous infrared galaxies, and also highlight the utility of integral field spectroscopy in elucidating subtle morphological differences in line emitting regions.

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T. W. Murphy Jr., B. T. Soifer, K. Matthews, L. Armus. 2000-06-22. The Active Nucleus in the Ultraluminous Infrared Galaxy IRAS 08311-2459. https://doi.org/10.1086/301550

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