Boundary blow-up and degenerate equations

Abstract

Let $\Omega\subset\mathbb R^2$ be a bounded domain of class $C^{2+\alpha}$, $0<\alpha<1$. We show that if $u$ is the solution of $\Delta u = 4\exp(2u)$ which tends to $+\infty$ as $(x,y)\to\partial\Omega$, then the hyperbolic radius $v=\exp(-u)$ is also of class $C^{2+\alpha}$ up to the boundary. The proof relies on new Schauder estimates for degenerate elliptic equations of Fuchsian type.