Observations on Gaussian upper bounds for Neumann heat kernels

Mourad Choulli (1) , Laurent Kayser (1) , El Maati Ouhabaz (2)

1 IECL - Institut Élie Cartan de Lorraine
2 IMB - Institut de Mathématiques de Bordeaux

Given a domain $\Omega$ of a complete Riemannian manifold $\mathcal{M}$ and define $\mathcal{A}$ to be the Laplacian with Neumann boundary condition on $\Omega$. We prove that, under appropriate conditions, the corresponding heat kernel satisfies the Gaussian upper bound $$ h(t,x,y)\leq \frac{C}{\left[V_\Omega(x,\sqrt{t})V_\Omega (y,\sqrt{t})\right]^{1/2}}\left( 1+\frac{d^2(x,y)}{4t}\right)^{\delta}e^{-\frac{d^2(x,y)}{4t}},\;\; t>0,\; x,y\in \Omega . $$ Here $d$ is the geodesic distance on $\mathcal{M}$, $V_\Omega (x,r)$ is the Riemannian volume of $B(x,r)\cap \Omega$, where $B(x,r)$ is the geodesic ball of center $x$ and radius $r$, and $\delta$ is a constant related to the doubling property of $\Omega$. As a consequence we obtain analyticity of the semigroup $e^{-t {\mathcal A}}$ on $L^p(\Omega)$ for all $p \in [1, \infty)$ as well as a spectral multiplier result.

Mots clés: Neumann Laplacian; Gaussian bounds; Riemannian manifolds.; Heat kernels

Domaines: Equations aux dérivées partielles [math.AP]; Mathématiques générales [math.GM]

Mourad Choulli, Laurent Kayser, El Maati Ouhabaz. Observations on Gaussian upper bounds for Neumann heat kernels. Bulletin of the Australian Mathematical Society, 2015, 92 (3), pp.429-439. ⟨10.1017/S0004972715000611⟩. ⟨hal-01119643⟩