A Method for Analyzing Weak Orbital Signals From Gaia

Analysing weak orbital signals in Gaia data

Author:

Lucy

Abstract:

Anomalous orbits are found when minimum-chi^{2} estimation is applied to synthetic Gaia data for weak orbital signals - i.e., orbits whose astrometric signatures are comparable to the single-scan measurement error (Pourbaix 2002). These orbits are nearly parabolic, edge-on, and their major axes align with the line-of-sight to the observer. Such orbits violate the Copernican principle (CPr) and as such could be rejected. However, the preferred alternative is to develop a statistical technique that incorporates the CPr as a fundamental postulate. This can be achieved in the context of Bayesian estimation by defining a Copernican prior. With this development, Pourbaix's anomalous orbits no longer arise. Instead, orbits with a somewhat higher chi^{2} but which do not violate the CPr are selected.

Other areas of astronomy where the investigator must analyse data from 'imperfect experiments' might similarly benefit from appropriately- defined Copernican priors.