Quasinormal modes of charged black holes in string theory

Both scalar and Dirac quasinormal modes in Garfinkle-Horowitz-Strominger black hole spacetime are studied by using the WKB approximation and the Poschl-Teller approximation. For scalar field, we find that the quasinormal modes (QNMs) with higher dilatons decay more rapidly than that with lower ones. However, this is not the case for mass m. Fields with higher mass will decay more slowly. Similar behaviors appear in the case of Dirac field. We also find that QNM frequencies evaluated by using WKB approximation and Poschl-Teller approximation have good agreement with each other when mode number n is small