Ring-down gravitational waves and lensing observables: How far can a wormhole mimic those of a black hole?

Understand

It has been argued that the recently detected ring-down gravity waveforms could be indicative only of the presence of light rings in a horizonless object, such as a surgical Schwarzschild wormhole, with the frequencies differing drastically from those of the horizon quasinormal mode frequencies $\omega _{\text{QNM}}$ at late times.

• While the possibility of such a horizonless alternative is novel by itself, we show by the example of Ellis-Bronnikov wormhole that the differences in $\omega _{\text{QNM}}$ in the eikonal limit (large $l$) need not be drastic.
• This result will be reached by exploiting the connection between $\omega _{\text{QNM}}$ and the Bozza strong field lensing parameters.
• We shall also show that the lensing observables of the Ellis-Bronnikov wormhole can also be very close to those of a black hole (say, SgrA$^{\ast }$ hosted by our galaxy) of the same mass.