Overview
- The peer‑reviewed study published June 19 used X‑ray light echoes from three extragalactic gamma‑ray bursts observed by NASA’s Chandra and ESA’s XMM‑Newton to map dust in three spiral arms.
- The team found that the Outer and Outer Scutum‑Centaurus arms lie about ten percent farther from Earth than earlier estimates based on rotation models.
- Researchers measured the full thickness of the most distant arm at roughly 3,500 light‑years, showing the result applies to the arm’s bulk rather than a single dust cloud.
- Because the method is purely geometric it avoids assumptions about how the Milky Way rotates, so the new distances may prompt revisions to estimates of the galaxy’s mass and rotation profile.
- Progress is limited by the rarity of usable gamma‑ray bursts that produce clear dust echoes, so further refinement will depend on finding more events and on future missions and data releases such as upcoming Gaia updates.