Excess 10 micron emission in extragalactic nuclei
- Harvard-Smithsonian Center for Astrophysics, Cambridge, MA (USA)
Intense 10-micron emission has been mapped with 4 arcsec resolution toward the nuclei of four nearby spiral galaxies: NGC 253, Maffei II, NGC 2903, and NGC 6946. In all four cases, the ratio of 10-micron to thermal radio emission is significantly higher than the ratio observed in Galactic H II regions. In addition, the 10-micron emission shows excellent spatial agreement with 6 cm radio continuum emission. This is surprising since the 10-micron emission is due to thermal dust emission, while the radio emission is predominantly nonthermal synchrotron emission. A new process that operates in galactic nuclei, but not in H II regions, may be responsible for much of the 10-micron emission. A population of small dust grains or large molecules heated by massive stars and SNRs may be responsible for an excess of 10-micron emission over the amount expected from radio free-free emission. The presence of an enhanced population of small dust grains in the nuclei of galaxies may result from dust destruction in shocks associated with the SNRs producing the radio emission, and the heating of these small grains may be via collisions with keV electrons associated with the SNRs. 71 refs.
- OSTI ID:
- 5250722
- Journal Information:
- Astrophysical Journal; (USA), Journal Name: Astrophysical Journal; (USA) Vol. 344; ISSN ASJOA; ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
Similar Records
3 kiloparsec radio disk and halo of NGC 1068
The size of NGC 4151 at 11. 2 microns
Related Subjects
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
BREMSSTRAHLUNG
CONFIGURATION
COSMIC DUST
COSMIC RADIO SOURCES
DISTRIBUTION
DUSTS
ELECTROMAGNETIC RADIATION
GALAXY NUCLEI
H2 REGIONS
HEATING
INFRARED RADIATION
INTERSTELLAR GRAINS
PARTICLES
RADIATIONS
SPATIAL DISTRIBUTION
SPIRAL CONFIGURATION
SUPERNOVA REMNANTS
SYNCHROTRON RADIATION