Cross-correlation and maximum-likelihood analysis: a new approach to combining cross-correlation functions

This paper presents a new approach to combining cross-correlation functions. The combination is based on a maximum-likelihood approach and uses a non-linear combination scheme. It can be effective for radial velocity analysis of multi-order spectra, or for analysis of multiple exposures of the same object. Simulations are presented to show the potential of the suggested combination scheme. The technique has already been used to detect a very faint companion of HD 41004.