\begin{table}%t2
%\centering
\par
\caption{Exploring the parameter space for $p$ and
$\tau_0$. The results of our adopted model are given in the first
column. These results already take the opacity to photon escape
into account.\label{deg}}
\begin{tabular}{lllllll }
\hline\hline
$F(E > E_{0})$ & $ p=2.3$        & $ p=2.3$        & $ p=2.3$        & $ p=2.2$          & $ p=2.2$       & $ p=2.2$   \\
                & $\tau_0=10$ Myr & $\tau_0=5$ Myr & $\tau_0=1$ Myr & $\tau_0=10$ Myr   & $\tau_0=5$ Myr & $\tau_0=1$ Myr \\
 \hline
\par
$E_{0}=100$ MeV  &  2.32E-8   & 2.36E-8  & 2.21E-8  &  2.95E-8   &    2.97E-8  &   2.75E-8\\
$E_{0}=200$ GeV  &  1.60E-12  & 1.23E-12 & 4.76E-13 &  4.04E-12  &    3.08E-12 &   1.15E-12\\
$E_{0}=600$ GeV  &  3.61E-13  & 2.67E-13 & 8.98E-14 &  1.00E-12  &    7.34E-13 &   2.40E-13\\
$E_{0}=1$ TeV    &  1.78E-13  & 1.29E-13 & 4.10E-14 &  5.16E-13  &    3.70E-13 &   1.14E-13\\
$E_{0}=2$ TeV    &  6.29E-14  & 4.46E-14 & 1.31E-14 &  1.92E-13  &    1.35E-13 &   3.87E-14\\
\par
\hline
\end{tabular}
\end{table}