literature

On the waveforms of gravitationally lensed gravitational waves

Feb 15, 2017
5 pages
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Abstract: (arXiv)
Strong lensing by intervening galaxies can produce multiple images of gravitational waves from sources at cosmological distances. These images acquire additional phase-shifts as the over-focused wavefront passes through itself along the line of sight. Time domain waveforms of Type-II images (associated with saddle points of the time delay) exhibit a non-trivial distortion from the unlensed waveforms. This phenomenon is in addition to the usual frequency-independent magnification, and happens even in the geometric limit where the wavelength is much shorter than the deflector's gravitational length scale. Similarly, Type-III images preserve the original waveform's shape but exhibit a sign flip. We show that for non-precessing binaries undergoing circular inspiral and merger, these distortions are equivalent to rotating the line of sight about the normal to the orbital plane by 4545^\circ (Type II) and 9090^\circ (Type III). This effect will enable us to distinguish between the different topological types among a set of multiple images, and give us valuable insight into the lens model. Furthermore, we show that for eccentric binaries, the waveform of a Type-II image is distorted in a manner that is inequivalent to a change of the source's orbital parameters.
Note:
  • 5 pages, 4 figures, comments welcome
  • gravitational radiation: emission
  • gravitational radiation detector
  • gravitational radiation: polarization
  • star: binary
  • gravitation: lens
  • phase shift
  • time delay
  • star: rotation
  • galaxy
  • numerical calculations