21-25 March 2022
Salon de actos del IATA
Europe/Madrid timezone

Interference signatures in the gravitational lensing of gravitational waves

24 Mar 2022, 16:11
Salón de Actos del IATA

Salón de Actos del IATA


Mrs. Helena Ubach (Universitat de Barcelona, ICCUB)


When gravitational waves propagate near massive objects, they are deflected as a result of gravitational lensing. This phenomenon is already known for electromagnetic waves, and it is expected for gravitational waves to be a promising new instrument in astrophysics. When the time delay between the different paths is comparable with the wave’s period, interference and diffraction appear due to lensing, and they are imprinted in the waveform, as a “beating pattern”. These effects are likely to be observed near the caustics, but the short-wave asymptotics associated with the geometrical optics approximation breaks down close to the caustic, where wave optics should be used. In this talk I will describe the crossover from wave optics to geometrical optics for the point mass lens model, where two parameters – the angular position of the source respect to the caustic, and the Fresnel number, which is the ratio between the Schwarzschild radius and the wavelength – are used to characterize the lensing effect. We obtain an interference pattern for the transmission factor, which allows us to suggest a simple formula for the onset of geometrical-optics oscillations which relates the Fresnel number with the angular position of the source in units of the Einstein angle

Presentation Materials

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