The vulnerability to single-detector instrumental artifacts in standard
detection methods for long-duration quasimonochromatic gravitational waves from
nonaxisymmetric rotating neutron stars [continuous waves (CWs)] was addressed
in past work [D. Keitel et al., Phys. Rev. D 89, 064023 (2014).] by a Bayesian
approach. An explicit model of persistent single-detector disturbances led to a
generalized detection statistic with improved robustness against such
artifacts. Since many strong outliers in semicoherent searches of LIGO data are
caused by transient disturbances that last only a few hours, we extend the
noise model to cover such limited-duration disturbances, and demonstrate
increased robustness in realistic simulated data. Besides long-duration CWs,
neutron stars could also emit transient signals which, for a limited time, also
follow the CW signal model (tCWs). As a pragmatic alternative to specialized
transient searches, we demonstrate how to make standard semicoherent CW
searches more sensitive to transient signals. Considering tCWs in a single
segment of a semicoherent search, Bayesian model selection yields a new
detection statistic that does not add significant computational cost. On
simulated data, we find that it increases sensitivity towards tCWs, even of
varying durations, while not sacrificing sensitivity to classical CW signals,
and still being robust to transient or persistent single-detector instrumental
artifacts.Comment: 16 pages, 6 figures, REVTeX4.