# GWPAW 2017

30 May 2017 to 2 June 2017
Impérial Palace
Europe/Paris timezone

## Echoes from the Abyss: Evidence for Planck-scale structure at black hole horizons

1 Jun 2017, 09:20
15m
Impérial Palace

#### Impérial Palace

Allée de l'Impérial, Annecy
Invited talk

### Speaker

Mr Jahed Abedi (Sharif University of Technology)

### Description

In classical General Relativity (GR), an observer falling into an astrophysical black hole is not expected to experience anything dramatic as she crosses the event horizon. However, tentative resolutions to problems in quantum gravity, such as the cosmological constant problem, or the black hole information paradox, invoke significant departures from classicality in the vicinity of the horizon. It was recently pointed out that such near-horizon structures can lead to late-time echoes in the black hole merger gravitational wave signals that are otherwise indistinguishable from GR. We search for observational signatures of these echoes in the gravitational wave data released by advanced Laser Interferometer Gravitational-Wave Observatory (LIGO), following the three black hole merger events GW150914, GW151226, and LVT151012. In particular, we look for repeating damped echoes with time-delays of $8 M \log M$ (+spin corrections, in Planck units), corresponding to Planck-scale departures from GR near their respective horizons. Accounting for the look elsewhere'' effect due to uncertainty in the echo template, we find tentative evidence for Planck-scale structure near black hole horizons at $2.5\sigma$ significance level (corresponding to false detection probability of $1\%$). Future data releases from LIGO collaboration, along with more physical echo templates, will definitively confirm (or rule out) this finding, providing possible empirical evidence for alternatives to classical black holes, such as in firewall or fuzzball paradigms.

### Primary author

Mr Jahed Abedi (Sharif University of Technology)

### Co-authors

Ms Hannah Dykaar (Department of Physics, McGill University) Prof. Niayesh Afshordi (Perimeter Institute for Theoretical Physics)

 Slides