The essential spectrum of the nonself-adjoint Maxwell operator in a bounded domain (Q1270904)

The generalized Maxwell equation has the form \[ \begin{pmatrix} 0 & i\nabla\wedge\\ -i\nabla\wedge & 0\end{pmatrix} \begin{pmatrix} E\\ H\end{pmatrix}= M(x)\omega\begin{pmatrix} E\\ H\end{pmatrix}+ B(x) \begin{pmatrix} E\\ H\end{pmatrix}+ \begin{pmatrix} F_1\\ F_2\end{pmatrix},\;n\wedge E|_{\partial\Omega}= 0, \] where \(\wedge\) is the vector product. The Maxwell system with nonselfadjoint perturbation has a large essential spectrum (an interval or another nondiscrete set).