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Characterize the selection function of the Gaia NSS 4.1 run

Characterize the selection function of the Gaia DR4 preparatory Non-Single Star (NSS 4.1) run sufficiently to enable reliable estimation of how common Gaia BH3-like wide binary systems are within the processed population.

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Background

The authors explain that the NSS 4.1 run applied numerous magnitude, quality, and filtering criteria and yielded 1,469,196 orbital solutions from 10,450,939 sources. They note that these choices make the selection function nontrivial to describe.

Because the selection function is difficult to characterize, the authors state that it is not currently possible to estimate how common or rare systems like Gaia BH3 are in the surveyed sample, underscoring the need for a formal selection-function model.

References

The selection function of the NSS 4.1 run is not trivial to characterise, thus, it is not possible to estimate how common or rare are systems like Gaia BH3.

— Discovery of a dormant 33 solar-mass black hole in pre-release Gaia astrometry (2404.10486 - Collaboration et al., 16 Apr 2024) in Appendix A, Section ‘Astrometric processing in the NSS 4.1 run’