\begin{table}%t1
\caption{\label{tbl_pdf}A list of different PDFs used in this paper.}
%\centering
\par
\small
\begin{tabular}{ccc}
 \hline\hline
& &\\[-2ex] 
\multicolumn{2}{c}{$P_{\rm S}(B)$} & $P_{\rm
  A}(\theta_{B})$ \\[-2ex]
& &  \\
 \hline
& & \\[-2ex]
(i) & $P_{\rm D}(B)=\delta(B-B_{\rm 0})$
& $P_{\rm iso}(\theta_{B})=\sin\theta_{B}$\\
& & \\[-2ex]
(ii)& $P_{\rm M}(B) ={\frac{32}{\pi^2 B_{\rm 0}}} \left({{B}/{B_{\rm
      0}}}\right)^2
\exp\left[-{\frac{4}{\pi}}\left({{B}/{B_{\rm 0}}}\right)^2\right] $ &
$P_{\rm pl-c}(\theta_{B})
=(p+1)  |\cos\theta_{B}|^p \sin\theta_{B}$ \\
& & \\[-2ex]
(iii)& $P_{\rm G}(B) ={\frac{2}{\pi B_{\rm 0}}}
\exp\left[-{\frac{1}{\pi}}\left({{B}/{B_{\rm 0}}}\right)^2\right]$
& $P_{\rm pl-s}(\theta_{B})
=(\sin\theta_{B})^p \sin\theta_{B}/C_p$\\
& & \\[-2ex]
(iv)&  $P_{\rm E}(B)={1 \over B_{\rm 0} } \exp(-B/B_{\rm 0})$ & \\[1.7pt]
 \hline 
\end{tabular}
\end{table}