Numerical search for a potential planet sculpting the young disc of HD 115600

Abstract

Radial and azimuthal features (such as disc offsets and eccentric rings) seen in high resolution images of debris discs, provide us with the unique opportunity of finding potential planetary companions which betray their presence by gravitationally sculpting such asymmetric features. The young debris disc around HD 115600, imaged recently by the Gemini Planet Imager, is such a disc with an eccentricity 0.1<e<0.2 and a projected offset from the star of 4 AU. Using our modified N-body code which incorporates radiation forces, we firstly aim to determine the orbit of a hidden planetary companion potentially responsible for shaping the disc. We run a suite of simulations covering a broad range of planetary parameters using a Monte Carlo Markov Chain sampling method and create synthetic images from which we extract the geometric disc parameters to be compared with the observed and model-derived quantities. We then repeat the study using a traditional grid to explore the planetary parameter space and aim secondly to compare the efficiency of both sampling methods. We find a planet of 7.8 Jupiter mass orbiting at 30 AU with an eccentricity of e = 0.2 to be the best fit to the observations of HD 115600. Technically, such planet has a contrast detectable by direct imaging, however the system's orientation does not favour such detection. In this study, at equal number of explored planetary configurations, the Monte Carlo Markov Chain not only converges faster but provides a better fit than a traditional grid.