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Caption: Figure 5.
The plots in the first two rows show the χ2 maps at the best-fit contrast surface slice, with companions injected into the calibrated HIP 65426 data at a fixed position angle (θ = 60°, where θ is calculated counterclockwise with respect to the vertical axis), with varying separations and contrasts for six tests. The null (no-companion) χ2 values and the minimum χ2 values are provided at the tops of each of these plots. The test number is provided at the bottom right of each plot. The location of these injections (in the separation vs. contrast space) is shown in the bottom plot, with numbers and color-coded “⨂” symbols. The detection significance (k) of the best fit compared to the null model in each of the plots in the first two rows is given at the bottom left. The grid of concentric circles in the top two panels denotes the separation from the host star (null χ2 model). For cases with k > 3σ (tests 2, 3, 4, 5, and 6), the contour regions are kσ, (k − 1)σ, and (k − 2)σ from the null model value, respectively. For test 1, with k = 1σ, the contours are 1σ, 2σ, and 3σ from the minimum χ2 value. The bottom panel shows the 1σ region from the best-fit separation and the contrast point for each of the injection tests at the best-fit position-angle slice. The X-axis showing the separation is equivalent to the concentric circles’ separation grid in the above plots. The brown dashed line shows the calculated 5σ contrast curve from the HIP 65426 calibrated data (see Figure 6). It is evident that for injections near the contrast limit, companions can be recovered with ∼5σ confidence (even below separations of 0.5λ/D for test 2, although this causes a larger uncertainty in the retrieved contrast and separation, as seen in the bottom panel). At contrasts brighter than this, the recovered signal significance is considerably larger. However, at separations below 0.5λ/D and contrasts dimmer than the 5σ limit, the companion cannot be found (test 1 with k = 1σ shows a separation/contrast degeneracy in the bottom plot). These results are summarized in Table 4.
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