The origin of infrared emission from the nucleus of NGC 1068.
Abstract
Recent infrared observational results for the nucleus of the Seyfert galaxy NGC 1068 are reviewed and analyzed in terms consistent with information available at other wavelengths. It is concluded that the infrared and optical data imply that more than 85 percent of the infrared emission at 10 microns is radiation from dust grains in the nucleus. Observed reddening of spectral lines implies geometrical optical depths at visual wavelengths of about 7-15 if the nuclear dust cloud is approximately spherically symmetric. The dust grains emitting the infrared radiation could be silicates with a 10-micron optical depth near unity, but this identification is not uniquely established. The grains are heated radiatively by an underlying source or sources of radiation also responsible for ionizing the emission-line-producing gas. The underlying source could be nonthermal, or it could be a hot plasma. Physical constraints on each of these models are derived.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- April 1975
- DOI:
- 10.1086/153514
- Bibcode:
- 1975ApJ...197..297J
- Keywords:
-
- Galactic Nuclei;
- Galactic Radiation;
- Infrared Astronomy;
- Red Shift;
- Seyfert Galaxies;
- Cosmic Dust;
- Cosmic Plasma;
- Emission Spectra;
- Line Spectra;
- Synchrotron Radiation;
- Astrophysics