Multipole Analysis and Application to Supernova Remnant X-ray Images

We develop a multipole analysis method for images with a circular boundary, then apply it to supernova remnant (SNR) images. The morphology of SNR images is related to several factors, including the inhomogeneities of the supernova ejecta and of the circumstellar medium in which the ejecta and shock wave travel. The current multipole method corrects some errors in a previously presented method, and applies the new analysis to test for differences in X-ray image morphology between Type Ia and core-collapse type SNRs. We find there is no clear difference between the two SNR types in morphology as measured by multipole moments.