Recovering the structure of debris discs non-parametrically from images

Abstract

ABSTRACT Debris discs common around Sun-like stars carry dynamical imprints in their structure that are key to understanding the formation and evolution history of planetary systems. In this paper, we extend an algorithm (rave) originally developed to model edge-on discs to be applicable to discs at all inclinations. The updated algorithm allows for non-parametric recovery of the underlying (i.e. deconvolved) radial profile and vertical height of optically thin, axisymmetric discs imaged in either thermal emission or scattered light. Application to simulated images demonstrates that the de-projection and deconvolution performance allows for accurate recovery of features comparable to or larger than the beam or point spread function size, with realistic uncertainties that are independent of model assumptions. We apply our method to recover the radial profile and vertical height of a sample of 18 inclined debris discs observed with ALMA. Our recovered structures largely agree with those fitted with an alternative visibility-space de-projection and deconvolution method (frank). We find that for discs in the sample with a well-defined main belt, the belt radius, fractional width, and fractional outer edge width all tend to increase with age, but do not correlate in a clear or monotonic way with dust mass or stellar temperature. In contrast, the scale height aspect ratio does not strongly correlate with age, but broadly increases with stellar temperature. These trends could reflect a combination of intrinsic collisional evolution in the disc and the interaction of perturbing planets with the disc’s own gravity.

Topics & Concepts