The low radio frequency properties of the SNR Kes 79

CASTELLETTI G., GIACANI E., PARON S., DUBNER G.

Isla Margarita, Venezuela

Congreso; XII Latin American Regional International Astronomical Union Meeting; 2007

Unión Astronómica Internacional

Observations of the supernova remnants (SNRs) at meter and longer wavelengths are powerful tools to differentiate physical processes taking place either in the SNRs (e.g. shock acceleration) or in the interstellar medium intervening along the line of sight towards them (e.g. thermal absorption).Kes 79 (G33.6+0.1) is a Galactic SNR rich in spatial structures in both, radio and X-ray bands, that make it ideal for addressing questions of SNR physics. Its radio morphology at 1.5 GHz is dominated by a system of two concentric incomplete shells with diameters about 8' and 12'. Chandra observations of Kes 79 reveal many filaments, multiple partial shells, a loop, and a protrusion. The X-ray point source, CXOUJ 185238.6+004020, located close to the geometric center of the remnant was proposed to be the compact stellar remnant formed in the  supernova envent, although no evidence for a surrounding pulsar wind nebula was found in the X-rays. It has also been suggested that Kes 79 is interacting with a molecular cloud that appears to be partially surrounding its east and southeast borders.In this work we present new high quality images of Kes 79 obtained at low radio frequencies. The observations at 74 and 324 MHz were carried out using multiple-configurations of the Very Large Array (VLA) of the NRAO. We use these data and existing VLA observations at 1.5 GHz to perform an accurate study of the spectral index behaviour over the remnant and its relationship with the properties in the X-ray band of Kes 79. In addition, using HI and CO data from public databases we investigate the influence of the surrounding gas on the morphology of Kes 79.