New Gravitational Memories

Understand

The conventional gravitational memory effect is a relative displacement in the position of two detectors induced by radiative energy flux.

• We find a new type of gravitational `spin memory' in which beams on clockwise and counterclockwise orbits acquire a relative delay induced by radiative angular momentum flux.
• It has recently been shown that the displacement memory formula is a Fourier transform in time of Weinberg's soft graviton theorem.
• Here we see that the spin memory formula is a Fourier transform in time of the recently-discovered subleading soft graviton theorem.