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arXiv · astro-ph/0102159

NICS-TNG infrared spectroscopy of NGC1068: the first extragalactic measurement of [PII] and a new tool to constrain the origin of [FeII] line emission in galaxies

E. Oliva·A. Marconi·R. Maiolino·L. Testi·F. Mannucci·F. Ghinassi·J. Licandro·L. Origlia·C. Baffa·A. Checcucci·G. Comoretto·V. Gavryussev·S. Gennari·E. Giani·L. K. Hunt·F. Lisi·D. Lorenzetti·G. Marcucci·L. Miglietta·M. Sozzi·P. Stefanini·F. Vitali
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Abstract

We report 0.9-1.4 micron spectroscopic observations of NGC1068 collected during the commissioning phase of the near infrared camera spectrometer (NICS) of the Telescopio Nazionale Galileo (TNG). These yielded the first extragalactic measurement of [PII] (1.188 micron) line emission. In the central 0.75"x2" the [FeII]/[PII] line-intensity ratio is close to unity, similar to that measured in the Orion bar and a factor of about 20 smaller than in supernova remnants. This indicates that most of iron is locked into grains and, therefore, argues against shock excitation being the primary origin of [FeII] line emission in the central regions of NGC1068. We propose the [FeII]/[PII] ratio as a simple and effective tool to study and perhaps resolve the long debated questions related to the origin of [FeII] line emission and, more generally, to constrain the role of shock excitation in active galaxies.

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E. Oliva, A. Marconi, R. Maiolino, L. Testi, F. Mannucci, F. Ghinassi, J. Licandro, L. Origlia, C. Baffa, A. Checcucci, G. Comoretto, V. Gavryussev, S. Gennari, E. Giani, L. K. Hunt, F. Lisi, D. Lorenzetti, G. Marcucci, L. Miglietta, M. Sozzi, P. Stefanini, F. Vitali. 2001-02-09. NICS-TNG infrared spectroscopy of NGC1068: the first extragalactic measurement of [PII] and a new tool to constrain the origin of [FeII] line emission in galaxies. https://doi.org/10.1051/0004-6361%3A20010214

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