{"about":{"site":"https://codewithpapers.app","non_affiliation":"Code with Papers and Syntology are not affiliated with, endorsed by, or sponsored by Papers with Code, Meta, or the pwc-archive mirror.","licence":"CC BY-SA 4.0","licence_url":"https://creativecommons.org/licenses/by-sa/4.0/legalcode","attribution":"https://codewithpapers.app/attribution","modified":"archive material modified by Syntology; see the attribution page"},"url":"/paper/gw190521-may-be-an-intermediate-mass-ratio","title":"GW190521 may be an intermediate mass ratio inspiral","arxiv_id":"2010.12558","date":"2020-10-23","proceeding":null,"authors":["Alexander H. Nitz","Collin D. Capano"],"abstract":"GW190521 is the first confident observation of a binary black hole merger with total mass $M > 100\\,\\mathrm{M}_{\\odot}$. Given the lack of observational constraints at these masses, we analyze GW190521 considering two different priors for the binary's masses: uniform in mass ratio and source-frame total mass, and uniform in source-frame component masses. For the uniform in mass-ratio prior, we find that the component masses are $m_1^{\\mathrm{src}} = 168_{-61}^{+15}\\,\\mathrm{M}_{\\odot}$ and $m_2^{\\mathrm{src}} = 16_{-3}^{+33}\\,\\mathrm{M}_{\\odot}$. The uniform in component-mass prior yields a bimodal posterior distribution. There is a low-mass-ratio mode ($q<4$) with $m_1^{\\mathrm{src}} = 100_{-18}^{+17}\\,\\mathrm{M}_{\\odot}$ and $m_2^{\\mathrm{src}} = 57_{-16}^{+17}\\,\\mathrm{M}_{\\odot}$ and a high-mass-ratio mode ($q\\geq4$) with $m_1^{\\mathrm{src}} = 166_{-35}^{+16}\\,\\mathrm{M}_{\\odot}$ and $m_2^{\\mathrm{src}} = 16_{-3}^{+14}\\,\\mathrm{M}_{\\odot}$. Although the two modes have nearly equal posterior probability, the maximum-likelihood parameters are in the high-mass ratio mode, with $m_1^{\\rm src} = 171\\,M_{\\odot}$ and $m_2^{\\rm src} = 16\\,M_{\\odot}$, and a signal-to-noise ratio of $16$. These results are consistent with the proposed \"mass gap\" produced by pair-instability in supernova. Our results differ from those published in Abbott et al. (2020b). We find that a combination of the prior used and the constraints applied may have prevented that analysis from sampling the high-mass-ratio mode. An accretion flare in AGN J124942.3+344929 was observed in possible coincidence with GW190521 by the Zwicky Transient Facility (ZTF). We report parameters assuming a common origin; however, the spatial agreement of GW190521 and the EM flare alone does not provide convincing evidence for the association ($\\ln\\mathcal{B} \\gtrsim -4$).","url_abs":"https://arxiv.org/abs/2010.12558v2","url_pdf":"https://arxiv.org/pdf/2010.12558v2.pdf","source":{"archive":"pwc-archive (Hugging Face), CC BY-SA 4.0","snapshot":"2025-07-28","licence_url":"https://creativecommons.org/licenses/by-sa/4.0/legalcode","row_kind":"links_only","authors_date_abstract":"arXiv metadata, CC0 1.0 (https://info.arxiv.org/help/license), from the Kaggle arXiv metadata snapshot of 2026-09-12"},"code_links":[{"paper_slug":"gw190521-may-be-an-intermediate-mass-ratio","repo_url":"https://github.com/gwastro/GW190521","is_official":1,"mentioned_in_paper":1,"mentioned_in_github":1,"framework":"none","reach":null},{"paper_slug":"gw190521-may-be-an-intermediate-mass-ratio","repo_url":"https://github.com/gwastro/3-ogc","is_official":0,"mentioned_in_paper":0,"mentioned_in_github":1,"framework":"none","reach":null}],"tasks":[],"methods":[],"datasets_introduced":[],"methods_introduced":[],"results":[],"syntology":{"atlas_url":null,"mcp":null,"developers":"https://syntology.ai/developers"},"arxiv_metadata":null,"syntology_extracted_results":null}