DETERMINATION OF THE LONG-TIME DYNAMICS FOR THE 2D KELLER-SEGEL EQUATION AT CRITICAL MASS
Abstract
We consider the parabolic-elliptic Keller-Segel equation in two dimensions on the whole space. We prove that for arbitrary initial data with critical mass 8π and finite second momentum, all solutions have the same universal behaviour. They are globally defined and, asymptotically for large times, they converge to a renormalized stationary state of the equation which concentrates around the center of mass of the solution at a universal logarithmic-in-time scale. Our result holds for general solutions without symmetry assumptions, and we furthermore provide explicit convergence rates. In the radial case, by combining our result with previous ones (by Blanchet-Dolbeault-Perthame, Mizoguchi, and related works), this achieves a complete classification of the possible dynamics: for subcritical masses solutions converge to a self-similar expander, at the critical mass they concentrate a stationary state in infinite time at the aforementioned universal scale, and for supercritical masses they blow up in finite time by type II concentration of a stationary state at another universal scale. Our proof starts with soliton resolution, then controls the motion of the stationary state and the remainder in new spaces, and devises new techniques for the multi-scale linearized analysis, which eventually enables the stability and modulation analysis around an approximate solution.
Related
- A Li-Yau and Aronson-Bénilan approach for the Keller-Segel system with critical exponent
- Stability of the critical constant steady state of a Keller--Segel model
- Absence of critical mass phenomena in one-dimensional critical quasilinear Keller-Segel systems
- Identifying secondary critical mass levels in two- and higher-dimensional Keller-Segel systems
- CLASSIFICATION OF THE DYNAMICS OF RADIAL SOLUTIONS TO THE 2D PARABOLIC-ELLIPTIC KELLER-SEGEL SYSTEM
BibTeX
@misc{buseghin2026determination,
title = {{DETERMINATION OF THE LONG-TIME DYNAMICS FOR THE 2D KELLER-SEGEL EQUATION AT CRITICAL MASS}},
author = {Federico Buseghin and Charles Collot},
howpublished = {HAL},
year = {2026},
month = oct,
eprint = {2606.20866},
archivePrefix = {arXiv},
url = {https://hal.science/hal-05781856v1},
note = {CC BY-NC-ND 4.0},
}
RIS
TY - UNPB
TI - DETERMINATION OF THE LONG-TIME DYNAMICS FOR THE 2D KELLER-SEGEL EQUATION AT CRITICAL MASS
AU - Federico Buseghin
AU - Charles Collot
PY - 2026
DA - 2026/10/06
PB - HAL
UR - https://hal.science/hal-05781856v1
AB - We consider the parabolic-elliptic Keller-Segel equation in two dimensions on the whole space. We prove that for arbitrary initial data with critical mass 8π and finite second momentum, all solutions have the same universal behaviour. They are globally defined and, asymptotically for large times, they converge to a renormalized stationary state of the equation which concentrates around the center of mass of the solution at a universal logarithmic-in-time scale. Our result holds for general solutions without symmetry assumptions, and we furthermore provide explicit convergence rates. In the radial case, by combining our result with previous ones (by Blanchet-Dolbeault-Perthame, Mizoguchi, and related works), this achieves a complete classification of the possible dynamics: for subcritical masses solutions converge to a self-similar expander, at the critical mass they concentrate a stationary state in infinite time at the aforementioned universal scale, and for supercritical masses they blow up in finite time by type II concentration of a stationary state at another universal scale. Our proof starts with soliton resolution, then controls the motion of the stationary state and the remainder in new spaces, and devises new techniques for the multi-scale linearized analysis, which eventually enables the stability and modulation analysis around an approximate solution.
ER -