Gravity seminar - Alejandro Torres-Orjuela Seminar

Abstract: Most gravitational waves (GWs) sources are moving relative to us. One particularly important reason for their motion is the peculiar velocity of their host galaxies which is of the order of 1000 km/s. We show that a motion of the center-of-mass of the source can affect the modes of GWs, where the effect is proportional to the velocity of the source. The effect on the GWs modes in turn affects the overall frequency of the GW, thus leading to a phase shift. We study the impact of the excited modes on the measurability for the specific case of a circular, non-spinning extreme-mass-ratio inspiral. We find that the excitation of higher modes by a peculiar velocity of 1000 km/s can be measured for such inspirals with signal-to-noise ratios of 100 or more, and thus could bias parameter estimates if it is not taken into account. Moreover, this effect breaks the degeneracy between mass and Doppler shift in GWs observations, and opens a new possibility of detecting the motion of a GWs source even for constant velocities. Therefore, by including this effect in waveform models, we could measure the velocity dispersion of clusters of galaxies at distances inaccessible to light.