Fast trigger algorithms for binary coalescences

The construction of two broad bandwidth gravitational antennae (Virgo and Ligo) is now started. Such interferometric detectors will do a constant survey of the sky. It results in a huge amount of continuously recorded data, inconsistent with the need for a flexible and tunable off-line signal search. This requires on line triggers, selecting “gravitational wave signal candidates”. Such triggers do not perform on-line analysis but only a preselection of candidates which should then go trough a fully detailed off-line analysis. This work is a first attempt to study some simple on-line trigger algorithms for the future interferometric Virgo detector, looking for signals induced by binary coalescences. Firstly, we point out the conditions that on-line triggers must obey. Then, we show that, used as an on-line trigger, the standard method of matched-filtering has some problems to fulfil these conditions. In a third step, we propose and study possible trigger algorithms, focusing our attention on their efficiency, their ability to reduce the amount of data, their robustness in front of the first post-Newtonian term and, of course, their processing speed.