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March 1, 2026SHILAP Revista de lepidopterología0 citationsOpen Access

Coherence of Supermassive Black Hole Binary Demographics with the nHz Stochastic Gravitational-wave Background

KKK. KusakabeOsaka University of Economics YIYoshiyuki InoueOsaka University of Economics DTDaisuke ToyouchiOsaka University of Economics

Key Points

The research aims to refine the estimation of the stochastic gravitational-wave background using dual active galactic nuclei data.
Compiled observational data sets of dual active galactic nuclei and AGN X-ray luminosity functions.
Analyzed the dependence of dual AGN fractions on luminosity.
Compared findings with recent pulsar timing array gravitational-wave measurements.
The AGN-based model aligns with current gravitational-wave measurements within 2 σ – 4 σ uncertainties.
Identified supermassive black hole binaries as the main source of the nHz gravitational-wave signal.
Demonstrated consistency between electromagnetic and gravitational-wave observations.

Abstract

Abstract We present a refined estimation of the stochastic gravitational-wave background (SGWB) based on observed dual active galactic nuclei (AGNs) together with AGN X-ray luminosity functions, in light of recent Pulsar Timing Array (PTA) detections of an nHz SGWB. We identify a characteristic luminosity dependence in dual AGN fractions by compiling recent observational data sets, providing crucial constraints on supermassive black hole binary (SMBHB) populations. Our AGN-based model reproduces the current SGWB measurements within PTA observational uncertainties of 2 σ –4 σ , demonstrating consistency between electromagnetic and gravitational-wave observations. These findings establish SMBHBs as the dominant source of the nHz gravitational-wave signal, providing crucial insights into their demographics and evolution.

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