What question did this study set out to answer?

This research aims to extend the CCEGA echo protocol to include binary black hole mergers, identifying specific candidates.

June 27, 2026Open Access

P80 CCEGA Echo Protocol for Black Star Binary Mergers: GW241109₁15924 as First Candidate

Key Points

This research aims to extend the CCEGA echo protocol to include binary black hole mergers, identifying specific candidates.
Extended CCEGA protocol to binary black holes, targeting masses from 4.56 to 14.75 M☉.
Identified GW241109_115924 as the primary echo candidate with a total mass of 12.51 M☉.
Predicted echo timing using t_echo(M) curve and assessed remnant mass.
GW241109_115924 has a predicted remnant mass of 11.88 M☉ within uncertainties.
t_echo predicted at 16.4 ms with a possible range from 8.2 ms above to below.
Radion sidebands identified within the frequency range of 240 to 2400 Hz.

Abstract

The CCEGA falsification protocol (P49) targeted binary neutron star mergers as primary echo candidates. We extend the protocol to binary black hole mergers whose component masses fall within the CCEGA black star range 4. 56, 14. 75 M☉. GW241109₁15924 — the least massive BBH candidate in GWTC-5. 0, with total mass 12. 51 M☉ — is identified as the first concrete target. The estimated remnant mass 11. 88 M☉ falls within the black star range across all mass uncertainties. Using the tₑcho (M) curve from P77, we predict tₑcho = 16. 4 +8. 2/-8. 2 ms with radion sidebands Δf ∈ 240, 2400 Hz. O4b strain data are publicly available at GWOSC. This paper constitutes a pre-registered, falsifiable prediction prior to any echo search being conducted.

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