Original title: Charged black-hole binary radiation at second post-Newtonian order
Andrea Placidi, Elisa Grilli, Matteo Pegorin, Marta Orselli · September 2026
When two black holes orbit each other, they send out gravitational radiation, which ripples through space. If the black holes also carry electric charge, they emit both gravitational waves and electromagnetic radiation. Most models only describe neutral pairs, missing how charge alters the signal. The researchers calculated the radiation emitted by two non-spinning, charged black holes moving along quasi-adiabatic circular orbits at second post-Newtonian order, an approximation method for systems moving slower than light. They determined the total energy escaping out to infinity. Adding charge introduces a new dipolar electromagnetic emission and modifies the gravitational waves. The emitted radiation also creates a new memory effect, which leaves a lasting shift in the field. These calculations provide the groundwork to build wave models that check if real gravitational-wave signals show signs of electric charge.
Imagine two people dancing in a hall, clapping their hands in rhythm. If one wears a bell, the sound changes with each clap, and it might affect how they move together. In this paper, black holes are like the dancers, electric charge is the bell, and the radiation is the sound. The bell adds extra noise and alters the dance, just as charge adds light and changes gravitational waves.
This helps scientists check if black holes have electric charge by studying gravitational waves. It improves models for future astronomy observations.
The abstract does not mention testing against real data. It assumes non-spinning binaries with circular orbits, so results may not apply to spinning or eccentric systems. It is a theoretical calculation at 2PN order, laying groundwork for future models.
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Charged black-hole binary radiation at second post-Newtonian order — Andrea Placidi, Elisa Grilli, Matteo Pegorin et al.
Abstract licence: CC0
Explanation generated by Synthesis from the abstract — it is not the original paper. This is a preprint, so it hasn't necessarily been peer reviewed.