The Fermi Gamma-ray Space Telescope has produced our best view of the highest-energy electromagnetic radiation, gamma-rays. Among other things, it discovered an unpredicted excess of gamma-rays from the central regions of our Galaxy. We understand where most gamma-rays in our Galaxy come from, but this excess requires a new source of gamma-rays, for which two possibilities have been suggested. One is that there is a large number (~10,000) of millisecond radio pulsars, fast-spinning long-lived neutron stars, in the Galactic Center. It has been very difficult to find this predicted pulsar population, due to the obscuring effects of ionized gas on radio pulse signatures from pulsars at this distance. The other alternative is that dark matter particles, which should concentrate in the Galactic center, may occasionally annihilate with each other, producing gamma-rays. Dark matter, which makes up the majority of the Galaxy’s mass, is thought to be made of tiny particles that don’t interact with light, but we’ve been unable to detect it directly in Earth experiments so far. Thus determining which explanation is correct is of great interest; we will either discover a new population of pulsars, or find (indirect) evidence for a particle nature for dark matter. My team has found one intriguing possibility to test the millisecond pulsar explanation, looking at X-ray sources from the Galactic Center region, but we cannot yet rule out either explanation.