$L^2$ asymptotic profiles of solutions to linear damped wave equations

In this paper we obtain higher order asymptotic profilles of solutions to the Cauchy problem of the linear damped wave equation in ${\mathbf{\text{R}}}^n$ \begin{equation*} u_{tt}-\Delta u+u_t=0, \qquad u(0,x)=u_0(x), \quad u_t(0,x)=u_1(x), \end{equation*} where $n\in \mathbf{\text{N}}$ and $u_0$, $u_1\in L^2($\mathbf{\text{R}}$^n)$. Established hyperbolic part of asymptotic expansion seems to be new in the sense that the order of the expansion of the hyperbolic part depends on the spatial dimension.