Astronomy and Astrophysics – Astrophysics
Scientific paper
Jan 1981
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1981a%26a....94...29k&link_type=abstract
Astronomy and Astrophysics, Vol. 94, P. 29, 1981
Astronomy and Astrophysics
Astrophysics
95
Scientific paper
This work is the first in a series which present radio continuum observations of nearby galaxies at 2.8 cm wavelength using the 100-n telescope at Effelsberg. The present work includes NGC 253, 2146, 2403, 2841, 2903, 3031, 4258, 4490/85, 4631, 4736, 4826, 5055, 5194/95, 5457, 6946 and IC 342. These high sensitivity observations have become feasible with the development of the multiple-beam observing technique for mapping extended radio sources (Emerson et al., 1979). The spatial resolution (71") at this wavelength reduces the influence of the emission of the nuclear region on the general disk emission and, in some cases, is sufficient to resolve emission from individual spiral arms. The galaxies presented here include a subset of those mapped at 1415 MHz by van der Kruit (1973a,b), having Harvard magnitudes of 10m.5 or brighter (Shapley and Ames, 1932), and cover a range of declination down to -25°.
The results can be summarised as follows:
1. In none of the galaxies studied here has the integrated spectrum become flat - i.e. thermal - by 10.7 GHz. The relative amount of thermal emission from galaxies at radio wavelengths has been seriously overestimated by previous authors.
2. There is no strong correlation of integrated spectral index, or of thermal content at 10.7 GHz, with Bubble type or luminosity class. However, the average disk intensity is correlated with absolute magnitude.
3. For all galaxies studied a straight-line spectral index fits the data well over the frequency range at least from 408 MHz to 10.7 GHz. The mean straight-line slope, averaged over all galaxies studied, gives a spectral index of 0.71 ± 0.08, with peak deviations of only ± 0.14.
4. Wavelengths as short as ˜0.5 cm must be used before the integrated thermal emission nay be unambiguously separated from the integrated nonthermal component, and even shorter wavelengths must be used before the thermal radiation may be observed to be dominant.
Emerson Darrel T.
Klein Ulf
No associations
LandOfFree
A Survey of the Distributions of 2.8-CM Radio Continuum in Nearby Galaxies - Part One - Observations of 16 Spiral does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with A Survey of the Distributions of 2.8-CM Radio Continuum in Nearby Galaxies - Part One - Observations of 16 Spiral, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and A Survey of the Distributions of 2.8-CM Radio Continuum in Nearby Galaxies - Part One - Observations of 16 Spiral will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1050833