Exponential growth rates in a typed branching diffusion

• 成果类型: Article
• 署名作者: Git, Y.; Harris, J. W.; Harris, S. C.
• 署名单位: University of Cambridge; University of Bristol; University of Bath
• 刊物名称: ANNALS OF APPLIED PROBABILITY
• ISSN/ISSBN: 1050-5164
• DOI: 10.1214/105051606000000853
• 发表日期: 2007
• 页码: 609-653
• 关键词: brownian-motion; equation; proofs

摘要

We study the high temperature phase of a family of typed branching diffusions initially studied in [Asterisque 236 (1996) 133-154] and [Lecture Notes in Math. 1729 (2000) 239-256 Springer, Berlin]. The primary aim is to establish some almost-sure limit results for the long-term behavior of this particle system, namely the speed at which the population of particles colonizes both space and type dimensions, as well as the rate at which the population grows within this asymptotic shape. Our approach will include identification of an explicit two-phase mechanism by which particles can build up in sufficient numbers with spatial positions near -gamma t and type positions near kappa root t at large times t. The proofs involve the application of a variety of martingale techniques-most importantly a spine construction involving a change of measure with an additive martingale. In addition to the model's intrinsic interest, the methodologies presented contain ideas that will adapt to other branching settings. We also briefly discuss applications to traveling wave solutions of an associated reaction-diffusion equation.