Determine the nature of the Type I compact-object candidates

Determine whether Gaia DR3 3443894276188890752 (G3443) and Gaia DR3 1560560462739675904 (G1560) contain massive white dwarfs, neutron stars, faint stellar companions, or unresolved hierarchical systems by obtaining follow-up spectroscopy, ultraviolet constraints, and future astrometric orbital solutions.

Background

G3443 and G1560 are the two highest-priority candidates identified in the survey. Their single-lined spectra, minimum companion masses of approximately 1.04 and 1.18 solar masses, and absence of detectable optical-to-infrared or ultraviolet emission are consistent with dark compact companions, but these observations do not uniquely identify the companion types.

The authors explicitly state that additional spectroscopy, ultraviolet observations, and improved Gaia astrometric orbital constraints are needed to distinguish massive white dwarfs and neutron stars from faint stellar companions or unresolved hierarchical configurations. Gaia DR4 may improve the orbital-inclination constraints and thereby convert the current minimum masses into more reliable companion-mass estimates.

References

Nevertheless, their physical nature remains unconfirmed, and follow-up spectroscopy, ultraviolet constraints, and future astrometric orbital solutions are required to distinguish massive white dwarfs, neutron stars, and faint stellar companions or hierarchical configurations.

— A Sample of Long-Period Binaries with Dormant Compact-Object Candidates from LAMOST DR13 MRS and Gaia DR3  (2609.30764 - Zhou et al., 25 Sep 2026) in Section 5, Summary