Finite-time blowup in a fully parabolic chemotaxis model involving indirect signal production
Xuan Mao, Meng Liu, Yuxiang Li
TL;DR
The paper addresses finite-time blowup for a fully parabolic chemotaxis system with indirect signal production in a high-dimensional ball, proving that for any mass \(m>0\) there exist radial, nonnegative initial data with \(\int_\Omega u_0=m\) that blow up in finite time. The authors develop a memory-aware strategy by constructing a Lyapunov-based integral inequality for the cross-term \(\int_\Omega uv\), leveraging Pohožaev-type testing and delicate spatial-temporal estimates to bound the Laplacian of the concentration \(\Delta v\) and the associated energy, despite the presence of the memory term \(w_t\). A key contribution is showing that low initial energy forces blowup, and that initial data with arbitrarily large negative energy can be generated, implying a dense blowup regime in the admissible set. Together, these results advance understanding of blowup phenomena in high-dimensional chemotaxis with indirect signaling and memory effects.
Abstract
This paper is concerned with a parabolic-parabolic-parabolic chemotaxis system with indirect signal production, modelling the impact of phenotypic heterogeneity on population aggregation \begin{equation*} \begin{cases} u_t = Δu - \nabla\cdot(u\nabla v),\\ v_t = Δv - v + w,\\ w_t = Δw - w + u, \end{cases} \end{equation*} posed on a ball in $\mathbb R^n$ with $n\geq5$, subject to homogeneous Neumann boundary conditions. The system has a four-dimensional critical mass phenomenon concerning blowup in finite or infinite time according to the seminal works of Fujie and Senba [J. Differential Equations, 263 (2017), 88--148; 266 (2019), 942--976]. We prove that for any prescribed mass $m > 0$, there exist radially symmetric and nonnegative initial data $(u_0,v_0,w_0)\in C^0(\overlineΩ)\times C^2(\overlineΩ)\times C^2(\overlineΩ)$ with $\int_Ωu_0 = m$ such that the corresponding classical solutions blow up in finite time. The key ingredient is a novel integral inequality for the cross-term integral $\int_Ωuv$ constructed via a Lyapunov functional.
