gott-kaiser-stebbins (gks) e ect in an acceleratedexpanding universe

We want to nd the cosmological constant in uence on cosmic microwave background (cmb) temperature due to moving linear cosmic strings. using the space- time metric of a linear cosmic string in an accelerated expanding universe, the gott- kaiser-stebbins (gks) e ect, as an important mechanism in producing temperature discontinuity in the (cmb), is considered; then, its modi cation due to the e ect of the cosmological constant is calculated. the result shows that a positive cosmological constant (i.e. the presence of cosmic strings in an accelerated expanding universe) weakens the discontinuity in temperature so that a stronger resolution is needed to detect the corresponding in uences on the cmb power spectrum and anisotropy.