Tunneling effect and hawking radiation from a Gibbon-Maeda black hole by using Eddington-Finkelstein coordinates

In this paper, by using well-known Eddington-Finkelstein coordinates instead of Painleve coordinates, we study the tunneling effect of black holes. As examples of special static black holes, we calculate the tunneling rates of Gibbon-Maeda black holes. The result obtained by adopting Eddington-Finkelstein coordinates is in agreement with the Parikh's standard result, Gamma similar to exp(-2ImS), which adopts the Painleve coordinates. In addition, we discuss carefully the condition that the coordinates system in which we study the tunneling process should satisfy. In our opinion, the terms of the tunneling effect are not as strict as ones in Parikh's paper and could be softened properly.