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arXiv · 2606.06592

Measuring a Black Hole's Area Immediately after Merger: A Direct-Wave Test of Hawking's Area Law

Adrian Ka-Wai Chung·Kelvin Ka-Ho Lam·Anna Liu·Nicolas Yunes
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Abstract

Black-hole area is the geometric variable behind horizon thermodynamics. We introduce a gravitational-wave method to infer a Kerr-equivalent horizon area from direct waves in the near-merger signal, before quasinormal ringing dominates at late times. Applied to GW250114, and interpreting the fitted direct-wave frequency and damping rate as horizon quantities, we find that analyses initiated $3$--$4.5M$ before the peak-amplitude time yield an area consistent with the Kerr remnant. This result gives a first area measurement using direct waves and a new near-merger test of Hawking's area law.

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Adrian Ka-Wai Chung, Kelvin Ka-Ho Lam, Anna Liu, Nicolas Yunes. 2026-06-04. Measuring a Black Hole's Area Immediately after Merger: A Direct-Wave Test of Hawking's Area Law. https://arxiv.org/abs/2606.06592

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