Atomic Representation of Glitches - Preliminary Results

Glitches are transients of environmental or instrumental origin appearing in the data channel of existing large baseline interferometer based gravitational wave detectors. Their presence limits severely the performance of gravitational wave detection/estimation algorithms based on the customary Gaussian noise assumption, and requires adopting ad-hoc data laundering techniques. Modeling glitches is in important issue both for simulating the instruments' noise background and for designing gravitational wave detection algorithms with improved performance. We believe that glitches can be modeled as superpositions of very simple time-frequency atoms, and discuss the use of a Matching-Pursuit algorithm to decompose glitches into Sine-Gaussian and Ring-Down components. The method has been tested on the data-channel glitch database maintained by P. Saulson and co-Workers [1]. Preliminary results appear encouraging, and suggest that only a few atoms may be needed to represent most of the observed glitches.