Equality of the images of the extremal split-Jacobian fans

Prove or disprove that the fans associated to \(L_1\) and \(L_{d-1}\) have the same image in the moduli space \(M^{tr}_2\) of tropical curves of genus 2.

Background

The locus TLd\mathbb{T}\mathcal{L}_d of tropical genus-2 curves with dd-split Jacobians decomposes into components LkL_k indexed by units kZdk\in\mathbb{Z}_d^*. Each component is organized by a fan obtained from subdivisions of the positive quadrant and mapped linearly into M2trM^{tr}_2.

The cases L1L_1 and Ld1L_{d-1} have explicit fan descriptions, and the paper verifies that their images agree when d=3d=3, with sporadic higher-degree examples pointing in the same direction. A general proof is not supplied.

References

The fans associated to $L_1$ and $L_{d-1}$ have the same image in $M{tr}_2$.

Tropical split Jacobians of curves of genus 2 II  (2502.05624 - Cobigo, 8 Feb 2025) in Section 6.2, paragraph “Further Questions,” immediately after Theorem 6.??