Infrared-to-radio ratio within NGC 5236 (M83) and NGC 6946

Journal Article · Wed Mar 01 04:00:00 EST 1989 · Astrophys. J.; (United States)

DOI:https://doi.org/10.1086/185399· OSTI ID:6018453

Bicay, M D; Helou, G; Condon, J J

A detailed comparison of the distribution of 60-micron IR and 20-cm radio continuum emission within NGC 5236 (M83) and NGC 6946 is presented. In the disks of both galaxies, a slow decrease of the 60-micron-to-20-cm ratio with increasing radius is observed. Values of this ratio within the central regions are enhanced by roughly a factor of 3 with respect to the outer disks, whereas the corresponding enhancement in radio surface brightness is at least a factor of 20. The 100-micron-to-20-cm ratio shows a similar but shallower gradient. To account for these observations, it is suggested that spiral galaxies are characterized by an IR disk with a shorter scale length than that of the radio continuum disk, the latter being smeared as a result of cosmic-ray propagation. 21 references.

• Research Organization: California Inst. of Tech., Pasadena (USA); California Institute of Technology, Pasadena (USA); National Radio Astronomy Observatory, Charlottesville, VA (USA)
• OSTI ID: 6018453
• Journal Information: Astrophys. J.; (United States), Journal Name: Astrophys. J.; (United States) Vol. 338; ISSN ASJOA
• Country of Publication: United States
• Language: English

Related Subjects

640105* -- Astrophysics & Cosmology-- Galaxies
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
COMPARATIVE EVALUATIONS
CONFIGURATION
COSMIC RADIATION
COSMIC RADIO SOURCES
ELECTROMAGNETIC RADIATION
GALAXIES
INFRARED RADIATION
IONIZING RADIATIONS
MORPHOLOGY
RADIATIONS
RADIOWAVE RADIATION
SPIRAL CONFIGURATION
WAVE PROPAGATION