A chi² veto for continuous gravitational wave searches

$\chi^2$ vetoes are commonly used in searching for gravitational waves, in particular for broad-band signals, but they can also be applied to narrow-band continuous wave signals, such as those expected from rapidly rotating neutron stars. In this paper we present a $\chi^2$ veto adapted to the Hough transform searches for continuous gravitational wave signals; we characterize the $\chi^2$-significance plane for different frequency bands; and discuss the expected performance of this veto in LIGO analysis.