Wave equation for operators with discrete spectrum and irregular propagation speed

Abstract

Given a Hilbert space, we investigate the well-posedness of the Cauchy problem for the wave equation for operators with discrete non-negative spectrum acting on it. We consider the cases when the time-dependent propagation speed is regular, Hölder, and distributional. We also consider cases when it it is strictly positive (strictly hyperbolic case) and when it is non-negative (weakly hyperbolic case). When the propagation speed is a distribution, we introduce the notion of "very weak solutions" to the Cauchy problem. We show that the Cauchy problem for the wave equation with the distributional coefficient has a unique "very weak solution" in appropriate sense, which coincides with classical or distributional solutions when the latter exist. Examples include the harmonic oscillator and the Landau Hamiltonian on ${\mathbb{R}}^n$, uniformly elliptic operators of different orders on domains, Hörmander's sums of squares on compact Lie groups and compact manifolds, operators on manifolds with boundary, and many others.

40 pages. arXiv admin note: text overlap with arXiv:1611.05600

References in corpus (5)

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• Hyperbolic second order equations with non-regular time dependent coefficients
• Discrete coherent states for higher Landau levels
• Wave equation for sums of squares on compact Lie groups
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