Rate of caustic crossing microlensing events in stellar binary lenses with significant orbital motion

[2607.21845] Rate of caustic crossing microlensing events in stellar binary lenses with significant orbital motion Skip to main content Search Submit Donate Log in Astrophysics > Solar and Stellar Astrophysics arXiv:2607.21845 (astro-ph) [Submitted on 23 Jul 2026] Title: Rate of caustic crossing microlensing events in stellar binary lenses with significant orbital motion Authors: Arjun Murlidhar , B. Scott Gaudi , Todd. A. Thompson View PDF HTML (experimental) Abstract: Binary lens microlensing events in which the source crosses a caustic produce sharp, distinctive magnification peaks and can therefore be readily identified. In this paper, we explore the importance of binary orbital motion for the binary lens caustic crossing cross section. If the orbital timescale of the binary system is smaller than the Einstein ring crossing timescale, the caustics sweep out a larger area in the source plane, generally enhancing the cross section. We find that face-on binaries in circular orbits exhibit a substantial increase (up to 4$\times$) in the cross section for caustic crossings. However, highly inclined orbits produce a net decrease relative to a static face-on binary with the same semi-major axis. Using a sample of ~$2800$ synthetic binary microlensing events drawn from a realistic Milky Way population-synthesis model, we calculate the average change in the caustic crossing cross section for individual systems with and without orbital motion. Although orbital motion can significantly alter the cross section for specific geometries, we find that, when averaged over the full population, it produces only a small, negligible increase of ~$0.1\%$ in the average cross section. We also compute the overall rate of caustic crossing binary events in the simulated sample and find that, with sufficiently dense photometric sampling, $6.3 \pm 0.2\%$ of microlensing events with impact parameter $u_0 < 1$ should exhibit caustic crossings. This rate depends on the distributions of binary separation, mass ratio, and multiplicity of stars and compact objects, and can therefore be used to test our understanding of these underlying properties. Comments: 17 pages, 12 figures; Accepted for publication in ApJ Subjects: Solar and Stellar Astrophysics (astro-ph.SR) ; Earth and Planetary Astrophysics (astro-ph.EP); Astrophysics of Galaxies (astro-ph.GA) Cite as: arXiv:2607.21845 [astro-ph.SR] (or arXiv:2607.21845v1 [astro-ph.SR] for this version) https://doi.org/10.48550/arXiv.2607.21845 Focus to learn more arXiv-issued DOI via DataCite Journal reference: Arjun Murlidhar et al 2026 ApJ 1008 51 Related DOI : https://doi.org/10.3847/1538-4357/ae8d0c Focus to learn more DOI(s) linking to related resources Submission history From: Arjun Murlidhar [ view email ] [v1] Thu, 23 Jul 2026 22:14:55 UTC (4,787 KB) Full-text links: Access Paper: View PDF HTML (experimental) TeX Source view license Current browse context: astro-ph.SR < prev | next > new | recent | 2026-07 Change to browse by: astro-ph astro-ph.EP astro-ph.GA References & Citations SciX Google Scholar Semantic Scholar export BibTeX citation Bookmark Bibliographic Tools Bibliographic and Citation Tools Bibliographic Explorer Toggle Bibliographic Explorer ( What is the Explorer? ) Connected Papers Toggle Connected Papers ( What is Connected Papers? ) Litmaps Toggle Litmaps ( What is Litmaps? ) scite.ai Toggle scite Smart Citations ( What are Smart Citations? ) Code, Data, Media Code, Data and Media Associated with this Article alphaXiv Toggle alphaXiv ( What is alphaXiv? ) Links to Code Toggle CatalyzeX Code Finder for Papers ( What is CatalyzeX? ) DagsHub Toggle DagsHub ( What is DagsHub? ) GotitPub Toggle Gotit.pub ( What is GotitPub? ) Huggingface Toggle Hugging Face ( What is Huggingface? ) ScienceCast Toggle ScienceCast ( What is ScienceCast? ) Demos Demos Replicate Toggle Replicate ( What is Replicate? ) Spaces Toggle Hugging Face Spaces ( What is Spaces? ) Spaces Toggle TXYZ.AI ( What is TXYZ.AI? ) Related Papers Recommenders and Search Tools Link to Influence Flower Influence Flower ( What are Influence Flowers? ) Core recommender toggle CORE Recommender ( What is CORE? ) IArxiv recommender toggle IArxiv Recommender ( What is IArxiv? ) Author Venue Institution Topic About arXivLabs arXivLabs: experimental projects with community collaborators arXivLabs is a framework that allows collaborators to develop and share new arXiv features directly on our website. 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