Let $X$ be a smooth projective geometrically connected curve over a number field $K$. Assume that $g\geq 2$.
Does there exist a Néron model $\mathcal X$ for $X$ over $O_K$?
By a Néron model, I mean a smooth model (not necessarily proper) with the "Néron universal property": for any smooth $O_K$-scheme $\mathcal Y$,
$$\mathrm{Hom}(\mathcal Y, \mathcal X) = X(\mathcal Y_K).$$
Is the smooth locus of the minimal regular model of $X$ over $O_K$ a Néron model? Does base change help? That is, does there exist a Néron model for $X_L$ after some suitable base change $L/K$?
Note that if $\mathcal{X}$ is the smooth locus of the minimal regular model of $X$ over $O_K$, we have the "Néron" property $\mathcal{X}(O_K) = X(K)$. (In fact, the image of a section in the minimal regular model lies in the smooth locus.)
This question was asked on stackexchange four months ago:
http://math.stackexchange.com/questions/153369/do-neron-models-of-hyperbolic-curves-existhttps://math.stackexchange.com/questions/153369/do-neron-models-of-hyperbolic-curves-exist