{"title":"Gravitational wave decoupling in retrograde circumbinary disks","month":"11","language":[{"iso":"eng"}],"oa":1,"file_date_updated":"2026-02-10T07:19:52Z","status":"public","date_published":"2025-11-05T00:00:00Z","acknowledgement":"D.J.D., C.T., and D.O.N. acknowledge support from the Danish Independent Research Fund through Sapere Aude Starting grant No. 121587, led by D.J.D. We are grateful to the anonymous referee for the insightful comments and suggestions for improving the manuscript. This work was also supported in part by the LISA Preparatory Science Program (LPS) through NASA grant 80NSSC24K0440, by NASA Astrophysics Theory Program (ATP) grant 80NSSC22K0822, and by the European Union’s Horizon research and innovation program under Marie Sklodowska-Curie grant agreement No. 101148364. This work made use of the following software packages: Sailfish (J. Zrake & A. MacFadyen 2024), numpy (C. R. Harris et al. 2020), Python (G. Van Rossum & F. L. Drake 2009), and scipy (P. Virtanen et al. 2020; R. Gommers et al. 2024). Software citation information aggregated using The Software Citation Station (T. Wagg & F. S. Broekgaarden 2024; T. Wagg et al. 2024). The Tycho supercomputer hosted at the SCIENCE HPC center at the University of Copenhagen was used in this work.","quality_controlled":"1","OA_type":"gold","abstract":[{"text":"We present a study of the late-time interaction between supermassive black hole binaries and retrograde circumbinary disks during the period of gravitational wave-driven inspiral. While mergers in prograde disks have received extensive study, retrograde disks offer distinct dynamics that could promote mergers and produce unique observational signatures. Through 2D numerical hydrodynamical simulations, we explore the process of binary-disk decoupling, where the binary’s orbital decay rate is faster than the disk’s viscous response rate. We find the point of decoupling to be comparable in prograde and retrograde disks, suggesting that any associated electromagnetic (EM) signatures will be produced at comparable times preceding the merger. However, we find smaller central cavities for retrograde disks, likely leading to higher-frequency EM emissions and shorter postmerger rebrightening timescales compared to their prograde counterparts. Retrograde disks form intrabinary bridges, which are prone to instabilities when the viscosity is low. These instabilities manifest as quasiperiodic flares in the accretion rate, which may produce distinctive EM signatures for retrograde disks.","lang":"eng"}],"OA_place":"publisher","citation":{"mla":"O’Neill, David, et al. “Gravitational Wave Decoupling in Retrograde Circumbinary Disks.” <i>The Astrophysical Journal</i>, vol. 993, no. 2, 206, IOP Publishing, 2025, doi:<a href=\"https://doi.org/10.3847/1538-4357/ae0ca8\">10.3847/1538-4357/ae0ca8</a>.","short":"D. O’Neill, C. Tiede, D.J. D’Orazio, Z. Haiman, A. MacFadyen, The Astrophysical Journal 993 (2025).","chicago":"O’Neill, David, Christopher Tiede, Daniel J. D’Orazio, Zoltán Haiman, and Andrew MacFadyen. “Gravitational Wave Decoupling in Retrograde Circumbinary Disks.” <i>The Astrophysical Journal</i>. IOP Publishing, 2025. <a href=\"https://doi.org/10.3847/1538-4357/ae0ca8\">https://doi.org/10.3847/1538-4357/ae0ca8</a>.","ama":"O’Neill D, Tiede C, D’Orazio DJ, Haiman Z, MacFadyen A. Gravitational wave decoupling in retrograde circumbinary disks. <i>The Astrophysical Journal</i>. 2025;993(2). doi:<a href=\"https://doi.org/10.3847/1538-4357/ae0ca8\">10.3847/1538-4357/ae0ca8</a>","ista":"O’Neill D, Tiede C, D’Orazio DJ, Haiman Z, MacFadyen A. 2025. Gravitational wave decoupling in retrograde circumbinary disks. The Astrophysical Journal. 993(2), 206.","ieee":"D. O’Neill, C. Tiede, D. J. D’Orazio, Z. Haiman, and A. MacFadyen, “Gravitational wave decoupling in retrograde circumbinary disks,” <i>The Astrophysical Journal</i>, vol. 993, no. 2. IOP Publishing, 2025.","apa":"O’Neill, D., Tiede, C., D’Orazio, D. J., Haiman, Z., &#38; MacFadyen, A. (2025). Gravitational wave decoupling in retrograde circumbinary disks. <i>The Astrophysical Journal</i>. IOP Publishing. <a href=\"https://doi.org/10.3847/1538-4357/ae0ca8\">https://doi.org/10.3847/1538-4357/ae0ca8</a>"},"file":[{"date_created":"2026-02-10T07:19:52Z","content_type":"application/pdf","date_updated":"2026-02-10T07:19:52Z","file_id":"21205","file_name":"2025_AstrophysicalJournal_ONeill.pdf","creator":"dernst","access_level":"open_access","success":1,"checksum":"65d0a3af314b5706407ad1b57a4ea89d","relation":"main_file","file_size":8071909}],"issue":"2","article_number":"206","tmp":{"name":"Creative Commons Attribution 4.0 International Public License (CC-BY 4.0)","image":"/images/cc_by.png","short":"CC BY (4.0)","legal_code_url":"https://creativecommons.org/licenses/by/4.0/legalcode"},"ddc":["520"],"arxiv":1,"_id":"21123","has_accepted_license":"1","year":"2025","oa_version":"Published Version","publisher":"IOP Publishing","external_id":{"arxiv":["2501.11679"]},"PlanS_conform":"1","DOAJ_listed":"1","date_updated":"2026-02-10T07:22:28Z","volume":993,"department":[{"_id":"ZoHa"}],"date_created":"2026-01-31T09:28:50Z","publication_identifier":{"issn":["0004-637X"],"eissn":["1538-4357"]},"article_type":"original","publication_status":"published","day":"05","author":[{"last_name":"O’Neill","first_name":"David","full_name":"O’Neill, David"},{"full_name":"Tiede, Christopher","first_name":"Christopher","last_name":"Tiede"},{"first_name":"Daniel J.","last_name":"D’Orazio","full_name":"D’Orazio, Daniel J."},{"first_name":"Zoltán","last_name":"Haiman","orcid":"0000-0003-3633-5403","id":"7c006e8c-cc0d-11ee-8322-cb904ef76f36","full_name":"Haiman, Zoltán"},{"full_name":"MacFadyen, Andrew","first_name":"Andrew","last_name":"MacFadyen"}],"user_id":"2DF688A6-F248-11E8-B48F-1D18A9856A87","intvolume":"       993","article_processing_charge":"Yes","type":"journal_article","doi":"10.3847/1538-4357/ae0ca8","publication":"The Astrophysical Journal"}