Blow-up solutions for the steady state of the Keller-Segel system on Riemann surfaces

Abstract

We study the following Neumann boundary problem related to the stationary solutions of the Keller-Segel system, a basic model of chemotaxis phenomena: \[ \left\{\begin{array}{ll} -Δ_g u +βu =λ\left(\frac{Ve^u}{\int_Σ Ve^u d v_g}-1\right), &\text { in } \mathringΣ\\ \partial_{ ν_g} u=0, &\text { on } \partial Σ\end{array} \right.,\] on a compact Riemann surface $(Σ, g)$ of unit area, with interior $\mathringΣ$ and smooth boundary $\partial Σ$. Here, $Δ_g$ denote the Laplace-Beltrami operator, $dv_g$ the area element of $(Σ, g)$, and $ν_g$ the unit outward normal to $\partial Σ$ and $λ$ and $β$ are non-negative parameters, $V$ is non-negative with finite zero set. For any integers $m>0$ and $k,l\geq 0$ with $m=2k+l$, we establish a sufficient condition on $V$ for the existence of a sequence of blow-up solutions as $λ$ approaches the critical values $4πm$, which blows up at $k$ points in the interior and $l$ points on the boundary. Moreover, the study expands to the corresponding singular problem.