Model the impact of interlopers after BAO reconstruction

Derive an accurate model for the impact of small-displacement [O III]–Hβ interlopers on the reconstructed galaxy density field and its propagator, extending beyond the pre-reconstruction interloper model.

Background

The paper derives a model for the effect of small-displacement [O III]–Hβ interlopers on the propagator before BAO reconstruction. For the post-reconstruction case, the authors expect the interloper impact to be reduced, but the reconstructed displacement field and residual oscillations are not fully captured by the same model. They therefore use the pre-reconstruction form as a provisional approximation, leaving the exact post-reconstruction treatment unresolved.

References

For the case with BAO reconstruction, we expect that the interloper impact on the density field to be smaller than in the pre-reconstruction case; however, the exact modelling is left for future study.

— The Effect of Slitless Spectroscopic Redshift Uncertainty and Interlopers on BAO Measurements from CSST-like Samples  (2608.24276 - Ding et al., 25 Aug 2026) in Section 2.4, “Propagator” (paragraph introducing the interloper propagator model)