A family of filters to search for frequency dependent gravitational wave stochastic backgrounds

We consider a three-dimensional family of filters based on broken power-law spectra to search for gravitational wave stochastic backgrounds in the data from Earth-based laser interferometers. We show that such templates produce the necessary fitting factor for a wide class of cosmological backgrounds and astrophysical foregrounds, and that the total number of filters required to search for those signals in the data from first generation laser interferometers operating at the design sensitivity is fairly small.