Determine whether binary-black-hole boosting can provide the required flux enhancement

Determine whether dark matter boosted by binary black holes in the Galaxy can produce a flux enhancement of approximately three orders of magnitude, sufficient to make the thermal Higgsino interpretation of the LZ event compatible with the solar-neutrino constraint.

Background

The paper examines a possible high-velocity dark-matter component generated by binary black holes as an example of a rare process that can accelerate a small fraction of dark matter above the Galactic escape velocity. With the benchmark flux, this component permits an inelastic-dark-matter interpretation of the LZ event but does not produce enough events for the thermal Higgsino model to evade the solar-neutrino bound.

The authors note that a flux enhancement by three orders of magnitude would be needed. Whether such an enhancement is physically realizable is left unresolved; the paper mentions that additional intermediate-mass black holes in the Galactic nuclear star cluster could potentially increase the flux.

References

It is unclear if it is possible to find such a large flux enhancement, but we briefly mention that a similar boosted flux applies for the single BBH system consisting of Sagittarius A* and an intermediate mass black hole; but this flux could be enhanced simply if there were more such intermediate mass black holes in the nuclear star cluster.

— Testing the inelastic dark matter interpretation of the LZ event with heavy-element experiments  (2610.21041 - Graham et al., 15 Oct 2026) in Section 2.4, “Parameter space for $m_\chi=1.1$ TeV”