Generality of DSPL sensitivity to evolving dark energy

Determine whether the strong constraining power of SDSS J0946+1006 for the dark-energy evolution parameter w_a is a generic property of double-source-plane gravitational lenses or instead results from this system’s particularly favourable source-redshift configuration.

Background

The paper finds that SDSS J0946+1006 provides a highly complementary constraint in the w_0–w_a plane: it constrains w_a more precisely than w_0 and has posterior contours that are near-orthogonal to those of Pantheon supernovae and DESI BAO. This makes the system a competitive probe of evolving dark energy even when considered alone.

The authors explicitly caution that the result may not generalize to other double-source-plane lenses. A statistically significant sample of such systems is needed to determine whether J0946’s constraining power is representative or whether its source redshifts make it an outlier.

References

However, it is currently unknown whether this constraining power will be a generic property of DSPLs once a statistically significant sample is obtained; it may be that J0946 is an outlier, with particularly favourable redshifts for constraining the evolution of dark energy.

— Harnessing stellar kinematics to constrain dark energy with the double-source-plane gravitational lens SDSS J0946+1006  (2609.08573 - Ballard et al., 8 Sep 2026) in Section 4, “Constraints on evolving dark energy”