Feasibility of symmetry-based speckle noise reduction for faint companion detection

Great interest has been focused on the problem of detecting faint companions, possibly including extrasolar planets, very close to other stars. A promising approach involves coupling high-correction adaptive optics to coronagraphs, for which many new and innovative designs have emerged. Detection of faint companions will require suppression of noise due to fluctuating speckles from the remnant fraction of stellar light not adaptively controlled. At high correction, the speckle halo takes on distinct spatial symmetries that may allow partial speckle noise reduction through relatively simple post-processing that rejects one spatial symmetry in the image. This paper quantitatively examines potential companion-detection sensitivity improvements that might be expected, and shows that realistic operational parameters will allow them to be realized.