The [C II] 158 Micron Line Deficit in Ultraluminous Infrared Galaxies Revisited
Abstract
We present a study of the [C II] 157.74-micrometer fine-structure line in a sample of 15 ultraluminous infrared (IR) galaxies using the Long Wavelength Spectrometer (LWS) on the Infrared Space Observatory (ISO). We confirm the observed order of magnitude deficit (compared to normal and starburst galaxies) in the strength of the [C II] line relative to the far-infrared (FIR) dust continuum emission found in our initial report, but here with a sample that is twice as large. This result suggests that the deficit is a general phenomenon affecting 4 out of 5 ULIRGs. We present an analysis using observations of generally acknowledged photodissociation region (PDR) tracers, which suggests that a high ultraviolet flux incident on a moderate density n PDR could explain the deficit. However, comparisons with other ULIRG observations, including, and 6.2-micrometer polycyclic aromatic hydrocarbon (PAH) emission, suggest that high PDRs alone cannot produce a self-consistent solution that is compatible with all of the observations. We propose that non-PDR contributions to the FIR continuum can explain the apparent [C II] deficiency.
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 10, 2003
- Accession Number
- ADA465055
Entities
People
- C. C. Dudley
- D. Lutz
- E. Sturm
- John Fischer
- M. G. Wolfire
- M. L. Luhman
- R. Genzel
- S. Satyapal
Organizations
- United States Naval Research Laboratory