\begin{equation*}
\vec{\kappa}^{(eq)} = \Big( \rho,
0,
0,
0,
3 \rho c_s^2 ,
0,
0\Big)^T.
\end{equation*} 

%\begin{equation*}
%\vec{\kappa}^{(eq)} = \begin{pmatrix}\rho \\
%0\\
%0\\
%0\\
%3 {{{c_s}}^{2}} \rho \\
%0\\
%0\end{pmatrix}.
%\end{equation*} 
