Data Analysis

We developed a set of IDL procedures to generate the analysis products discussed below. Examples of the methods summarized here are shown in Figure 5.

• Radial Surface Brightness Profiles: computed by summing the X-ray events in annuli centered on the image, and dividing by the respective area of each annulus.

• Cumulative Radial Distributions (Encircled events): computed by summing the X-ray events within centered circular apertures of increasing radius, and normalizing the distribution to the total number of counts within a radius of 1.6 mm. Note that the central pixel is defined as 1 in our encircled counts plots (e.g. Figures 5, 14, 19).

• Marginal Distributions: computed as and in rectangular grids surrounding the X-ray spot.

• Orthogonal Image Slices: computed by extracting the the X-ray events along the CCD row and column that intersects the spot centroid, and dividing by the pixel area.

• Pulse Height (PH) Spectra: The charge in each 3 × 3 pixel event island was summed, after removing the bias charge from each pixel, and the histogram of pulse heights was plotted. Because the incident X-rays were nearly monochromatic with known energies, it was not necessary to apply a gain correction.

  

Figure 5: Examples of analysis products. Top row: marginal distribution (Z direction), encircled energy, and radial profile for H-IAI-CR-1.001. Bottom row: one-pixel-wide slice (Y direction) for H-IAI-CR-1.001 and pulse height spectrum showing pileup peaks for H-IAI-CR-1.004.

These methods of presenting the data were chosen for their sensitivity to distortions in the spot size and shape resulting from mirror nonparfocalization, telescope defocus (x-direction), scattering, photon event pileup, finite pixel size, and detector geometry.