Constraining the Mass of a Hypothetical Secondary Black Hole in M87 with the NANOGrav 15-Year Data Set

2025/06/05 by Motoki Kino, Kino, Motoki, Masahiro Nagashima +9 · 4 voices
Physics and Astronomy · #Astrophysical Phenomena and Observations #Astrophysics of Galaxies (astro-ph.GA) #Cosmology and Gravitation Theories #FOS: Physical sciences #General Relativity and Quantum Cosmology (gr-qc) #High Energy Astrophysical Phenomena (astro-ph.HE) #Relativity and Gravitational Theory #astro-ph.GA #astro-ph.HE #gr-qc

paper · pdf · doi:10.48550/arxiv.2506.12313

openalex publication_date 2025/06/14 · arxiv published 2025/06/14 · arxiv updated 2025/06/14 · openalex created_date 2025/10/13 · openalex updated_date 2026/07/28

Abstract

Galaxy mergers, each hosting a supermassive black hole (SMBH), are thought to form SMBH binaries. Motivated by recent observations from the East Asian VLBI Network (EAVN) showing periodic behavior in the M87 jet, a precession of about 11 years and a transverse oscillation of about 0.9 years, we constrain the mass of a hypothetical secondary black hole orbiting the primary SMBH in M87. To constrain the mass ratio between the primary SMBH (M₁) and the secondary black hole (M₂) defined as q ≡ M₂/M₁ ≤ 1, and the length of the semimajor axis of the binary system (a), we impose the following three constraints: (i) the lower limit of a, below which the SMBH binary is expected to merge. (ii) the strain amplitude of the gravitational wave background (GWB) at nanohertz frequencies shown in the NANOGrav 15-year dataset. (iii) a finite length of the semimajor axis of M₁, that can induce periodic behavior in the jet. By combining these constraints, we obtain the allowed parameter space for q and a. If either of the EAVN-detected periods (T) corresponds to the binary's orbital period, the allowed range of q is 6.9 × 10^-3 ≤ q ≤ 4.2 × 10^-2 for T ≈ 11 years, and 3.7× 10^-2 ≤ q ≤ 1 for T ≈ 0.9 years. VLBI astrometric monitoring of the jet base of M87 is essential to explore the allowed parameter space for q and a.

Citations

• M 87: a cosmic laboratory for deciphering black hole accretion and jet formation
• Imaging a ring-like structure and the extended jet of M87 at 86 GHz
• Black Hole-Disk Interactions in Magnetically Arrested Active Galactic Nuclei: General Relativistic Magnetohydrodynamic Simulations Using A Time-Dependent, Binary Metric
• Toward Microarcsecond Astrometry for the Innermost Wobbling Jet of the BL Lacertae Object OJ 287
• The NANOGrav 15 yr Data Set: Evidence for a Gravitational-wave Background
• Applications of the source-frequency phase-referencing technique for ngEHT observations
• First M87 Event Horizon Telescope Results. VIII. Magnetic Field Structure near The Event Horizon
• Ultra-light dark matter
• Book Review Interferometry and Synthesis in Radio Astronomy - 3rd Ed

Discussions

• #arXiv Constraining the Mass of a Hypothetical Secondary Black Hole in M87 with the NANOGrav 15-Year Data Set https://arxiv.org/abs/2506.12313 the allowed parameter space for q and a. [bsky, 4 points, 1 comments]
• #arXiv Constraining the Mass of a Hypothetical Secondary Black Hole in M87 with the NANOGrav 15-Year Data Set https://arxiv.org/abs/2506.12313 the allowed parameter space for q and a. [bsky, 1 points, 0 comments]
• Feed: "AAS Nova" By: Kerry Hensley on Thursday, September 18, 2025 [bsky, 0 points, 0 comments]
• # arXiv Constraining the Mass of a Hypothetical Secondary Black Hole in M87 with the NANOGrav 15-Year Data Set https:// arxiv.org/abs/2506.12313 the allowed parameter space for q and a. [mastodon, 0 points, 0 comments]

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