Echoes from the Abyss: The Holiday Edition!

Abstract

In a recent paper (arXiv:1612.00266), we reported the results of the first search for echoes from Planck-scale modifications of general relativity near black hole event horizons using the public data release by the Advanced LIGO gravitational wave observatory. While we found tentative evidence (at $\simeq 3 σ$ level) for the presence of these echoes, our statistical methodology was challenged by Ashton, et al. (arXiv:1612.05625), just in time for the holidays! In this short note, we briefly address these criticisms, arguing that they either do not affect our conclusion or change its significance by $\lesssim 0.3σ$. The real test will be whether our finding can be reproduced by independent groups using independent methodologies (and ultimately more data).

Figures (2)

• Figure 1: Same as Fig. 4 in Abedi:2016hgu, but over an extended range of $x=\frac{t_{\rm echo} - t_{\rm merger}}{\Delta t_{\rm echo}}$. The SNR peaks at the predicted value of $x=1$ have 2.0$\sigma$ and 2.9$\sigma$ significance, for GW150914 and combined events respectively.
• Figure 2: SNR$^{2}$ near the expected time of merger echoes (Eq. \ref{['t_echo_meas']}) for GW150914 in Hanford (red) and Livingston (green) detectors. Interestingly, their SNR ratio $2.74/3.37 = 0.81$ is comparable to the SNR ratio for the main event $13.3/18.6 = 0.72$. Note that, unlike Fig. (\ref{['SNR_fig']}), here we have fixed the echo parameters to their best fit values for combined detectors.