In contrast to gravity in the weak-field regime, which has been subjected to numerous experimental tests, gravity in the strong-field regime is largely unconstrained by experiments. Indeed, a large class of gravity theories can be constructed that obey the Einstein equivalence principle and cannot be rejected by solar system tests, but that diverge from general relativity in the strong-field regime. I show that such theories predict black holes and neutron stars with significantly different properties than their general relativistic counterparts. I then discuss how recent observations with current X-ray observatories, such as Chandra and XMM-Newton, have provided interesting new constraints on strong-field gravity.

Refreshments will be served in the Steward Observatory lobby at 3:30pm.