Natural log of evidence (top panel) and natural log of maximum likelihood (bottom panel) for different models, relative to our featured model (three uniform-temperature circular spots plus a modulated Gaussian-profile power law). From the left, these models are numbers 1, 2, 3, 4, and 5 in our list (see Section 4 and Table 2). Models 1 and 2, which do not include a modulated power-law component, are substantially disfavored compared with the models that do include this component. Therefore, to allow those models to fit on the plots, the −10 to 0 portions of both panels are linear, whereas the portions below −10 are logarithmic (the first horizontal dashed line is 10 below the reference model; the second is 20 below; and so on). We conclude that the modulated power-law component must be included in a viable model of this source. We also see that, in terms of the evidence, the two-circle, two-oval, and three-circle models (all with a modulated power law) are all comparable with each other. The three-circle model, however, has a substantially larger maximum log likelihood than the other models.