Cygnus A: Long-Wavelength, High-Resolution Observations with the Very Large Array and Long Wavelength Array
Abstract
As part of a program to study particle acceleration in radio galaxies, we have observed Cygnus A at 74 and 327 MHz with the Very Large Array's Pietown link, obtaining angular resolutions of approximately 10" and 3", respectively. These observations are among the highest angular resolutions obtained below 1000 MHz for this object and serve as prototypes for observations with the Long Wavelength Array. Guided by a 151 MHz image from MERLIN and the 327 MHz image, we have estimated the 74 MHz emission from the hot spots. We confirm that the emission from both the western and eastern hot spots flattens at low frequencies and that there is a spectral asymmetry between the two. For the eastern hot spot, a low-energy cutoff in the electron energy spectrum appears to explain the flattening, which implies a cutoff Lorentz factor γ' 300, though we cannot exclude the possibility that there might be a moderate level of free-free absorption. For the western hot spot, the current observations are not sufficient to distinguish between a free-free absorped power-law spectrum and a synchrotron self-absorbed spectrum. We also anticipate obtaining similar observations of 3C 219, and a preliminary analysis of these will be presented as well.The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc. Basic research in radio astronomy at the NRL is supported by the Office of Naval Research.
- Publication:
-
American Astronomical Society Meeting Abstracts #208
- Pub Date:
- June 2006
- Bibcode:
- 2006AAS...208.5201L