Work

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

Year: 2026

Type: article

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.

Source: The Astrophysical Journal

DOI: 10.3847/1538-4357/ae3962

Authors: Katsunori Kusakabe, Yoshiyuki Inoue, Daisuke Toyouchi

Institutions: The University of Osaka, Kavli Institute for the Physics and Mathematics of the Universe, RIKEN, RIKEN Center for Interdisciplinary Theoretical and Mathematical Sciences, The University of Tokyo

Language: English

Topic: Pulsars and Gravitational Waves Research

Subfield: Astronomy and Astrophysics

Field: Physics and Astronomy

Domain: Physical Sciences

Open Access status: gold

Estimated APC paid: $4,499

Funders: Ministry of Education, Culture, Sports, Science and Technology, National Astronomical Observatory of Japan, Japan Society for the Promotion of Science