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Peer-reviewedCC BY 4.0The Astrophysical Journal

Quasars Microlensed by Milky Way Stars: Two Upcoming Events Predicted with Gaia Data Release 3

  • Qiming Wang1,2
  • Yiping Shu1
  • Jinyi Shangguan3
  1. 1Chinese Academy of Sciences
  2. 2University of Science and Technology of China
  3. 3Peking University
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Abstract

Galactic quasar microlensing, in which Milky Way stars lens quasars, is a largely unexplored class of Druckmüller microlensing phenomenon. With reduced degeneracies relative to conventional microlensing, Galactic quasar microlensing provides a unique and powerful approach for determining lens masses and probing quasar structures on milliarcsecond (mas) scales. Although several candidate Galactic quasar microlensing events have been reported, the lack of identified lens objects and timely follow-up observations prevents definitive discrimination between microlensing and alternative explanations. Leveraging Gaia Data Release 3 (DR3) astrometry, we forecast close alignments between Milky Way stars and quasars that will produce detectable microlensing signals. Computing trajectories of 210 million Gaia sources with significant proper motions and crossmatching them with 3 million known quasar candidates, we identify two upcoming Galactic quasar microlensing events with minimum projected separations of 1 5 − 2 + 2 and 16 − 12 + 17 mas in 2032 and 2073, respectively. The lens stars of these two events are consistent with M dwarfs, and follow-up observations promise to measure their masses to ≲10% precision. This work demonstrates that the discovery of the first Galactic quasar microlensing events is now within reach. This new class of microlensing events will establish a new observational pathway for studying individual stars in the Milky Way and compact structures in distant quasars.

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Cite

BibTeXRIS
BibTeX
@article{wang2026quasars,
  title = {{Quasars Microlensed by Milky Way Stars: Two Upcoming Events Predicted with Gaia Data Release 3}},
  author = {Qiming Wang and Yiping Shu and Jinyi Shangguan},
  journal = {The Astrophysical Journal},
  year = {2026},
  month = oct,
  doi = {10.3847/1538-4357/aea148},
  url = {https://iopscience.iop.org/article/10.3847/1538-4357/aea148},
  note = {CC BY 4.0},
}
RIS
TY  - JOUR
TI  - Quasars Microlensed by Milky Way Stars: Two Upcoming Events Predicted with Gaia Data Release 3
AU  - Qiming Wang
AU  - Yiping Shu
AU  - Jinyi Shangguan
PY  - 2026
DA  - 2026/10/15
JO  - The Astrophysical Journal
DO  - 10.3847/1538-4357/aea148
UR  - https://iopscience.iop.org/article/10.3847/1538-4357/aea148
AB  - Galactic quasar microlensing, in which Milky Way stars lens quasars, is a largely unexplored class of Druckmüller microlensing phenomenon. With reduced degeneracies relative to conventional microlensing, Galactic quasar microlensing provides a unique and powerful approach for determining lens masses and probing quasar structures on milliarcsecond (mas) scales. Although several candidate Galactic quasar microlensing events have been reported, the lack of identified lens objects and timely follow-up observations prevents definitive discrimination between microlensing and alternative explanations. Leveraging Gaia Data Release 3 (DR3) astrometry, we forecast close alignments between Milky Way stars and quasars that will produce detectable microlensing signals. Computing trajectories of 210 million Gaia sources with significant proper motions and crossmatching them with 3 million known quasar candidates, we identify two upcoming Galactic quasar microlensing events with minimum projected separations of 1 5 − 2 + 2 and 16 − 12 + 17 mas in 2032 and 2073, respectively. The lens stars of these two events are consistent with M dwarfs, and follow-up observations promise to measure their masses to ≲10% precision. This work demonstrates that the discovery of the first Galactic quasar microlensing events is now within reach. This new class of microlensing events will establish a new observational pathway for studying individual stars in the Milky Way and compact structures in distant quasars.
SN  - 0004-637X
SN  - 1538-4357
ER  -