N. Dadhich et N. Banerjee, Global monopoles and scalar fields as the electrogravity dual of Schwarzschild space-time, MOD PHY L A, 16(18), 2001, pp. 1193-1200
We prove that both global monopole and minimally coupled static zero mass s
calar field are electrogravity dual of the Schwarzschild solution or flat s
pace and they share the same equation of state, T-0(0) - T-i(i) = 0. This p
roperty was however known for the global monopole space-time while it is fo
r the first time being established for the scalar field. In particular, it
turns out that the Xanthopoulos-Zannias scalar field solution is dual to fl
at space.