research
Twenty-Five Radio Bursts Weigh the Metals Around the Milky Way
Combining fast-radio-burst dispersion with oxygen absorption points to an enriched, uneven circumgalactic medium rather than pristine inflow alone.
Summary
Combining fast-radio-burst dispersion with oxygen absorption points to an enriched, uneven circumgalactic medium rather than pristine inflow alone.
The Milky Way circumgalactic medium stores gas moving into and out of the galaxy, but its metallicity is difficult to measure. This analysis combines dispersion measures from 25 fast-radio-burst sightlines with metallicity-dependent oxygen-absorption estimates. Depending on assumptions about diffuse baryons outside the galaxy, the median inferred hot-phase metallicity ranges from 0.12 to 0.39 times solar. Even the conservative lower-bound case exceeds typical expectations for intergalactic accretion, supporting retention of metal-enriched feedback material. Large sightline-to-sightline variation suggests an anisotropic, multiphase halo. The inference depends strongly on foreground and baryon-fraction assumptions and is not a direct abundance measurement at each location.
Why it matters
Combining fast-radio-burst dispersion with oxygen absorption points to an enriched, uneven circumgalactic medium rather than pristine inflow alone.
Limits and context
- The inference depends strongly on foreground and baryon-fraction assumptions and is not a direct abundance measurement at each location.
Key claims
Combining fast-radio-burst dispersion with oxygen absorption points to an enriched, uneven circumgalactic medium rather than pristine inflow alone.
Qualification: The inference depends strongly on foreground and baryon-fraction assumptions and is not a direct abundance measurement at each location.
Evidence: source-2026-10-30-015
Sources
- arXiv preprint 2610.40609, original v1arXiv · primary research
Corrections
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