Data quality and vetoes for the gravitational-wave burst and inspiral analyses in Virgo's first science run

Gravitational-wave (GW) searches are impaired by the presence of transient sources of noise that can masquerade as a GW signal. This is particularly a burden when these events have larger amplitudes and hence generate an increase in the background for the loudest triggers. Requiring a coincidence between the output of the Virgo and LIGO detectors does not completely eliminate their effect. It is therefore necessary to suppress them in the Virgo GW channel trigger list. Many of these events are due to sources of noise intrinsic to the detector, or environmental disturbances. We here show that many of these sources of noise have been identified, looking at the Virgo GW and auxiliary channels. Data quality vetoes have been defined specifically for the GW burst and inspiral searches, and applied to Virgo data in the joint LIGO/Virgo analyses. Then we show their effect on the analyses performed on the data collected during the first Virgo science run.