We probe the possibility that Centaurus A ( Cen A ) is a point source of ultra-high energy cosmic rays ( UHECR ) observed by PAO , through the statistical analysis of the arrival direction distribution .
For this purpose , we set up the Cen A dominance model for the UHECR sources , in which Cen A contributes the fraction f _ { C } of the whole UHECR with energy above 5.5 \times 10 ^ { 19 } { eV } and the isotropic background contributes the remaining 1 - f _ { C } fraction .
The effect of the intergalactic magnetic fields on the bending of the trajectory of Cen A originated UHECR is parameterized by the gaussian smearing angle \theta _ { s } .
For the statistical analysis , we adopted the correlational angular distance distribution ( CADD ) for the reduction of the arrival direction distribution , and the Kuiper test to compare the observed and the expected CADDs .
Using CADD , we identify the excess of UHECR in the Cen A direction and fit the CADD of the observed PAO data by varying two parameters f _ { C } and \theta _ { s } of the Cen A dominance model .
The best-fit parameter values are f _ { C } \approx 0.1 ( The corresponding Cen A fraction observed at PAO is f _ { C,PAO } \approx 0.15 , that is , about 10 out of 69 UHECR . )
and \theta _ { s } = 5 ^ { \circ } with the maximum probability P _ { max } = 0.29 .
Considering the uncertainty concerning the assumption of isotropic background in the Cen A dominance model , we extend the viable parameter ranges to the 2 \sigma band , 0.09 \lesssim f _ { C,PAO } \lesssim 0.25 and 0 ^ { \circ } \lesssim \theta _ { s } \lesssim 20 ^ { \circ } .
This result supports the existence of a point source extended by the intergalactic magnetic fields in the direction of Cen A .
If Cen A is actually the source responsible for the observed excess of UHECR , the average deflection angle of the excess UHECR implies the order of 10 { nG } intergalactic magnetic field in the vicinity of Cen A .