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The link between IRAS spectra and near-infrared emission features in external galaxiesThe relationship in external galaxies between the presence of the near-infrared (NIR) emission features attributed to polycyclic aromatic hydrocarbon (PAH) molecules, and the far-infrared (FIR) properties as observed by IRAS, is investigated. It is found that whenever the NIR features are absent in a galaxy, the FIR spectrum displays an enhancement at shorter wavelengths relative to normal galaxies. This enhancement is always associated with a strong activity in the galactic nucleus. Some Seyfert galaxies do not exhibit such an infrared signature and therefore they are probably energetically dominated by star-formation processes. Finally, the importance of hard UV photons and of the hot medium in the narrow line region of active nuclei is emphasized in relation to the survival of the PAH molecules. In this frame, the absence of PAHs in the galactic center could be taken as evidence for the presence of an active nucleus.
Document ID
19890034590
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Desert, F. X.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Dennefeld, M.
(CNRS Institut d'Astrophysique, Paris, France)
Date Acquired
August 14, 2013
Publication Date
November 1, 1988
Publication Information
Publication: Astronomy and Astrophysics
Volume: 206
Issue: 2, No
ISSN: 0004-6361
Subject Category
Astrophysics
Accession Number
89A21961
Distribution Limits
Public
Copyright
Other

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