Critical norm blow-up rates for the energy supercritical nonlinear heat equation

TL;DR

This paper classifies the blow-up rates of the critical norm for solutions to the energy supercritical nonlinear heat equation, establishing their optimality without symmetry assumptions, and introduces a new strategy based on quantitative regularity criteria.

Contribution

It provides the first classification of blow-up rates for the critical norm in energy supercritical heat equations without symmetry or sign restrictions, using a novel quantitative approach.

Findings

Blow-up rates are classified and shown to be optimal.

The new strategy does not require energy structure assumptions.

Results extend potential blow-up rate analysis to other nonlinear parabolic equations.

Abstract

We prove the first classification of blow-up rates of the critical norm for solutions of the energy supercritical nonlinear heat equation, without any assumptions such as radial symmetry or sign conditions. Moreover, the blow-up rates we obtain are optimal, for solutions that blow-up with bounded $L^{n(p-1)/2,\infty}(\mathbf{R}^n)$-norm up to the blow-up time. We establish these results by proving quantitative estimates for the energy supercritical nonlinear heat equation with a robust new strategy based on quantitative $\varepsilon$-regularity criterion averaged over certain comparable time scales. With this in hand, we then produce the quantitative estimates using arguments inspired by Palasek [31] and Tao [38] involving quantitative Carleman inequalities applied to the Navier-Stokes equations. Our work shows that energy structure is not essential for establishing blow-up rates of the critical norm for parabolic problems with a scaling symmetry. This paves the way for establishing such critical norm blow-up rates for other nonlinear parabolic equations.