Calculating the Flux Density Decay of Cas A with LWA1
Abstract
The supernova remnant Cassiopeia A (Cas A) is one of the brightest objects on the low frequency radio sky in the Northern hemisphere. Due to the expansion of the cloud of material left from the supernova, its flux density keeps decreasing at a rate of ~0.7-0.8% per year. Deviations from this steady decay were noted and a systematic monitoring of Cas A is recommended in order to better trace these fluctuations. The first station of the Long Wavelength Array, co-located with the Very Large Array in New Mexico, has been performing a systematic monitoring of the flux density ratio between the radio galaxy Cygnus A and Cas A below 100 MHz since 2013. In combination with archival observations using the VLA 74 MHz system, this dataset covers a wide range of temporal scales from days to decades. This analysis is expected to lead to a better understanding of the reliability of Cas A for low frequency flux density calibration and provide insights into the physical interaction between the expanding supernova remnant shell and the interstellar medium through light curve analysis. I will present an update on the monitoring effort and preliminary light curves that reveal a non-linear decay of the flux density of Cas A.
- Publication:
-
American Astronomical Society Meeting Abstracts #229
- Pub Date:
- January 2017
- Bibcode:
- 2017AAS...22914802E