Excitation of gravitational wave modes by a center-of-mass velocity of
  the source
  Most gravitational wave (GW) sources are moving relative to us. This motion
is often closely related to the environment of the source and can thus provide
crucial information about the formation of the source and its host. Recently,
LIGO and Virgo detected for the first time the subdominant modes of GWs. We
show that a motion of the center-of-mass of the source can affect these modes,
where the effect is proportional to the velocity of the source. The effect on
the GW modes in turn affects the overall frequency of the GW, thus leading to a
phase shift. We study the impact of this effect on LIGO/Virgo detections and
show that it is detectable for sources with high mass ratios and inclinations.
This effect breaks the degeneracy between mass and Doppler shift in GW
observations, and opens a new possibility of detecting the motion of a GW
source even for constant velocities.
