Can Black Holes Have Hair? A stability test of Kerr-Sen Black Holes*

Einstein's theory of general relativity (GR) has matched every experimental test performed so far. However, because GR does not agree with quantum mechanics, there is reason to believe that GR might be incomplete. One proposed alternative to GR is Einstein-Maxwell-dilaton-axion gravity. EMDA gravity arises from low-energy string theory. This theory allows for black holes with mass, rotation, charge, and a scalar field . One possible black hole solution to EMDA is the Kerr-Sen black hole. Our ultimate goal is to test the stability of Kerr-Sen black holes in this theory. To test this we will simulate head on collisions of two Kerr-Sen Black holes and see if the extra fields proposed by this theory persist. We perform our simulations using a numerical relativity code called Dendro.