Published online by Cambridge University Press: 20 November 2018
Let $J$ be a Jacobian variety with toric reduction over a local field
$K$. Let
$J\,\to \,E$ be an optimal quotient defined over
$K$, where
$E$ is an elliptic curve. We give examples in which the functorially induced map
${{\Phi }_{J}}\,\to \,{{\Phi }_{E}}$ on component groups of the Néron models is not surjective. This answers a question of Ribet and Takahashi. We also give various criteria under which
${{\Phi }_{J}}\,\to \,{{\Phi }_{E}}$ is surjective and discuss when these criteria hold for the Jacobians of modular curves.