A complete theory of smoothable compactified Jacobians of nodal curves

Abstract

We introduce and study a new class of compactified Jacobians for nodal curves, that we call compactified Jacobians of vine type, or simply V-compactified Jacobians. This class is strictly larger than the class of classical compactified Jacobians, as constructed by Oda-Seshadri, Simpson, Caporaso and Esteves. We characterize V-compactified Jacobians as the compactified Jacobians that can arise as limits of Jacobians of smooth curves under a one-parameter smoothing of the nodal curve, extending previous works on fine compactified Jacobians by Pagani-Tommasi and Viviani to the case of all compactified Jacobians.

61 pages, 3 figures, v2: The proof that V-compactified Jacobians give rise to a proper good moduli space has been removed as it now follows as a special case of Theorem A in arXiv:2505.08609. Some other minor changes throughout