Speaker
Description
High-resolution astronomical imaging is conventionally constrained by the diffraction limit, which imparts a wavelength-dependent scaling on the impulse response of the optical system. This inherent chromaticity implies that images of unresolved sources encode their spectra. We demonstrate that with a differentiable forward model coupled with a rigorous information-theoretic approach, optimal recovery of such information is possible. We further derive analytic relations for wavelength-estimation for ideal monochromatic point sources. Such is achieved via computation of the expected Fisher information matrix, whose eigenvectors form a set of information-orthogonal basis functions of the spectrum, with the number of recoverable modes scaling with the field-of-view and signal-to-noise of the data. This same Fisher-information formalism can be applied to the question of contrast, dictating the fundamental limits of dynamic range given a particular (in general, position-dependent) point-spread function. This approach generalises two-point resolution criteria (e.g. Reyleigh, Sparrow) to their information-theoretic limits with wide-reaching implications, particularly in direct imaging of exoplanets. These results suggest ways forward in data analysis, spectroscopy on broadband images without dispersive elements, and information-optimal telescope design.
| I am the presenting author | Yes |
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