SGWB
Contact A. Mercer
A stochastic background of gravitational waves (GW) is a signal tipically emerging from a large number of unresolved, independent and uncorrelated sources. GW stochastic backgrounds fall into two rather broad classes based on the production mechanism: primordial backgrounds and astrophysical backgrounds. A primordial GW stochastic background is produced by physical processes which took place in the early Universe. Examples of such processes are the parametric amplification of zero-point fluctuations of the space time metric during a phase of accelerated expansion (inflation) and phase transitions associated with the temperature reaching some critical scales (e.g. the electro-weak scale). An astrophysical background of gravitational radiation results from incoherent superposition of radiation emitted by large populations of individual astrophysical sources, e.g rapidly spinning neutron stars and short-period binary systems of compact objects. For a review on sources of stochastic GW background see M. Maggiore, Gravitational wave experiments and early universe cosmology, Phys Rep 331 283 (2000)
A stochastic GW background is a random process which in a single detector is indistinguishable from the instrumental noise. In order to detect such a signal, the optimal signal processing strategy calls for cross-correlation between the data streams of two or more instruments operating in coincidence, possibly widely separated in order to minimise the effects of common noise sources. For more details see e.g. B. Allen and J. Romano, Detecting a stochastic background of gravitational radiation: Signal processing strategies and sensitivities, Physical Review D 59, 102001 (1999)
The Birmingham Group is actively involved in the development of a data analysis pipeline for searching for stochastic backgrounds in the LIGO and GEO data. In the framework of the GEO and LIGO Science Collaboration (LSC) we are currently working on a search algorithm for stochastic backgrounds characterised by a constant spectrum which will be used in the forthcoming analysis of the recent and future Science runs of GEO600 and LIGO.
Selected publications:
B. Abbott et al, Analysis of First LIGO Science Data for Stochastic Gravitational Waves
External links:
LSC - LIGO Scientific Collaboration
LSC Stochastic sources Upper limit group
