Speaker
Description
Recent observations by the Event Horizon Telescope of the image of the supermassive Black Hole at the center of M87 and SagA* provide a window into the strong-field regime of gravity. Several authors have studied the constraints that black hole shadow measurements cast on specific gravitational solutions or on the coefficients of more general parametrized frameworks. When multiple parameters are present, these constraints are usually degenerate. In this work, we tackle the inverse problem of gravitational imaging, i.e. we aim to reconstruct the metric and accretion disk profile from the image seen by a far-away observer. We allow the metric and disk profile to be described by an arbitrary frame or basis in functional space. By performing a Fisher Matrix analysis, and identifying the principal components of the covariance matrix, we extract the most prominent features in the metric and disk profile that produce the image. We test this framework in a simplified model by injecting mock deviations of the Schwarzchild metric surrounded by a spherical accretion disk. Since the problem is highly degenerate, we are able to reconstruct the metric deviations and disk profile provided that we use strong enough theoretical priors on the metric and disk profile.