Abstract
The early and precise localization of gravitational waves (GWs) is pivotal in detecting their electromagnetic (EM) counterparts, especially for binary neutron stars (BNS) and neutron star-black hole binaries (NSBH). In this letter, we pioneer the exploration of utilizing the higher harmonic modes induced by the eccentricity of compact binaries to localize GWs with ground-based detectors even before the quadrupole baseline mode enters the detector band. Our theoretical analysis marks a first in proposing a strategy for gaining the earliest possible warning and maximizing preparation time for observing pre and/or postmerger EM counterparts. We simulate three typical binaries from GWTC-3 with eccentricities ranging from 0.05 to 0.4. Our results reveal that the third-generation (3G) detectors (low-frequency cutoff ) can accumulate sufficient signal-to-noise ratios through higher modes before the onset of the baseline mode entry into the band. Notably, relying solely on the higher modes, the 3G detector network achieves an average localization on the order of around 1–1.8 hours before the merger of a GW170817-like BNS, and approximately 18–30 minutes prior to the merger of a GW200115-like NSBH. A localization is attainable even 2–4 hours prior to a BNS merger. Moreover, in the near face-on orientations which are generally more favorable for EM counterpart detection, the localization can be further improved.
- Received 25 October 2023
- Revised 11 January 2024
- Accepted 9 April 2024
DOI:https://doi.org/10.1103/PhysRevD.109.104041
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