Deconvolution of Images Taken with the Suzaku X-Ray Imaging Spectrometer

Abstract

Abstract We present a non-iterative method to deconvolve the point spread function (PSF) from images taken with the Suzaku X-ray Imaging Spectrometer (XIS). The method is optimized for analyses of extended sources with high photon statistics. Suzaku has four XIS detectors, each with its own X-ray CCD and X-Ray Telescope (XRT), and has been providing opportunities in spatially-resolved analyses of extended objects. The detectors, however, suffer from broad and position-dependent PSFs with their typical half-power diameter (HPD) of $\sim$110$^{\prime\prime}$. The present method is intended to recover spatial resolution to $\sim$15$^{\prime\prime}$ over a dynamic range of around 1:100 in the brightness without assuming any source model. Our deconvolution proceeds in two steps: An XIS image is multiplied by the inverse response matrix, calculated from its PSF after rebinning CCD pixels to larger-size tiles (typically 6$^{\prime\prime}$$\times$ 6$^{\prime\prime}$). The inverted image is then adaptively smoothed. The PSF is modeled on a ray-tracing program and an observed point-source image. The method has been applied to images of Centaurus A, PSR B1509$-$58 and RCW 89 taken by one XIS (XIS 1). The results have been compared with images taken with Chandra to conclude that the spatial resolution has been recovered to $\sim$20$^{\prime\prime}$ down to regions where the surface brightness is about 1:50 of the brightest tile. We believe the spatial resolution and the dynamic range can be improved with higher fidelity PSF modeling and higher precision pointing information.