\begin{table}%t4
%\centering
\par
\caption{Values of postshock electronic number density for a few regions (see Fig.~\ref{hardness_ratio}) using
Eq. (\ref{ne_hat}) with $\theta_{{\rm s}} = 32 \arcmin$.
$D_{1}$ is the distance in units of 1 kpc.
The selected regions are those for which the 
thermal emission is detected for temperatures of $\sim$$ 0.5{-}0.6$~keV.\label{tab_ne}}
\begin{tabular}{ccc} \hline \hline
Region & \multicolumn{1}{c}{$\theta_{{\rm r}}$ ($\arcmin$)} & \multicolumn{1}{c}{$\hat{n}_{{\rm e}}$ ($10^{-2} D_{1}^{-1/2}$ cm$^{-3}$)}  \\ \hline
1 & 28 & 1.95 (1.58--2.31) \\
2 & 9 & 2.37 (1.97--2.76) \\
6 & 14 & 2.40 (1.91--2.86) \\
8 & 20 & 1.87 (1.33--2.22) \\ \hline
\end{tabular}
\end{table}