High Dispersion Measure Fast Radio Bursts from Young, Dust-Poor H II Regions

[2608.27779] High Dispersion Measure Fast Radio Bursts from Young, Dust-Poor H II Regions Skip to main content Search Submit Donate Log in Astrophysics > Astrophysics of Galaxies arXiv:2608.27779 (astro-ph) [Submitted on 27 Aug 2026] Title: High Dispersion Measure Fast Radio Bursts from Young, Dust-Poor H II Regions Authors: Eliza C. Diggins (1), Calvin Leung (1, 2, and 3), Wenbin Lu (1 and 4) ((1) UC Berkeley Department of Astronomy, (2) UC Berkeley Department of Physics, (3) Miller Institute of Basic Research UC Berkeley, (4) UC Berkeley Theoretical Astrophysics Center) View PDF HTML (experimental) Abstract: Several repeating fast radio burst (FRB) sources exhibit host-frame dispersion measure (DM) excesses far exceeding those expected from the interstellar medium in their host galaxies, implying a substantial contribution from the sub-kiloparsec-scale local environment. These excesses are often attributed to an expanding supernova remnant; however, this canonical interpretation does not explain their apparent preference for low-metallicity dwarf galaxy hosts, suggesting that the mechanism producing the local DM is coupled to the properties of the host galaxy. In this work, we investigate whether the H II regions generated by young, massive stellar associations can simultaneously explain these DM excesses and their preferential association with low-metallicity dwarf galaxies. We develop a semi-analytic model for FRB-emitting neutron stars in cluster-forming molecular clouds and perform idealized one-dimensional radiation-hydrodynamic simulations using time-dependent ionizing luminosities from pySTARBURST99. Our findings indicate that high-mass $(M_\star \sim 10^5-10^6\;M_\odot)$, young ($\lesssim 10\;{\rm Myr}$) stellar associations in low-metallicity environments (LMC-like or lower) can produce ${\rm DM}_{\rm HII} \gtrsim 10^3\;{\rm pc\;cm^{-3}}$ for FRBs that form early ($\lesssim 5$ Myr) and remain embedded in the ionized gas. The low-mass/metallicity preference arises from dust: absorption of the Lyman continuum suppresses the ionized column at higher metallicity, making extreme local DMs preferentially generated in dust-poor, low-metallicity environments. At cosmological distances, selection of a metal-rich, massive, and quiescent host galaxy sample where such extreme local contributions are likely to be suppressed may yield a cleaner FRB sample for using extragalactic DMs as tracers of the intervening intergalactic and circumgalactic media. Comments: 32 pages, 9 figures, 1 table Subjects: Astrophysics of Galaxies (astro-ph.GA) ; High Energy Astrophysical Phenomena (astro-ph.HE); Solar and Stellar Astrophysics (astro-ph.SR) Cite as: arXiv:2608.27779 [astro-ph.GA] (or arXiv:2608.27779v1 [astro-ph.GA] for this version) https://doi.org/10.48550/arXiv.2608.27779 Focus to learn more arXiv-issued DOI via DataCite Submission history From: Eliza Diggins [ view email ] [v1] Thu, 27 Aug 2026 23:23:10 UTC (8,263 KB) Full-text links: Access Paper: View PDF HTML (experimental) TeX Source view license Current browse context: astro-ph.GA < prev | next > new | recent | 2026-08 Change to browse by: astro-ph astro-ph.HE astro-ph.SR References & Citations INSPIRE HEP 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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