Testing Theories of Gravity with Galactic Center Pulsars Geoffrey C. Bower (Academia Sinica Institute of Astronomy & Astrophysics) Shami Chatterjee (Cornell Univ.) James M. Cordes (Cornell Univ.) Paul Demorest (NRAO) Julia S. Deneva (George Mason Univ.-NRL) Jason Dexter (Max Planck Institute for Extraterrestrial Physics) Ralph Eatough (Max-Planck-Institut für Radioastronomie) Michael Kramer (Max-Planck-Institut für Radioastronomie) Joseph Lazio (Jet Propulsion Laboratory, California Institute of Technology) Kuo Liu (Max-Planck-Institut für Radioastronomie) Scott Ransom (NRAO) Lijing Shao (Max-Planck-Institut für Radioastronomie) Norbert Wex (Max-Planck-Institut für Radioastronomie) Robert Wharton (Max-Planck-Institut für Radioastronomie) A pulsar orbiting the central supermassive black hole in the Milky Way Galaxy, Sgr A*, represents a clock moving in the gravitational potential of a black hole, with which powerful tests of theories of gravity can be conducted. Furthermore, the number and distribution of pulsars in the Galactic center provide probes of the star formation, stellar dynamics, and stellar evolution of this region. While there is ample evidence to suggest that there should be a (large) population of pulsars within the central parsecs, despite years of searching, only a handful of pulsars in the central 0.5° are known, only one of which is within 1 pc (projected) of Sgr A*. This deficit of pulsars is attributed commonly to significant interstellar scattering. With its combination of high sensitivity and frequency coverage above 10 GHz, the ngVLA would be key to finding many more pulsars in the Galactic center. A consequence of its combination of frequency coverage and high sensitivity is that the ngVLA could also be capable of finding pulsar-black hole (PSR-BH) binaries in the Milky Way Galaxy. These binaries would also be powerful tests of theories of gravity and complement LIGO-Virgo measurements of the mergers of distant NS-BH binaries. However, such PSR-BH binaries are likely to be deep within the Galactic plane and potentially also affected significantly by interstellar scattering. Once again, the combination of high sensitivity and frequency coverage above 10 GHz would allow the ngVLA unparalleled opportunities to find and study such PSR-BH systems. SC, JMC, PD, JL, and SR are members of the NANOGrav Physics Frontier Center, which is supported by the National Science Foundation award 1430284. MK, LS, NW, and RW acknowledge financial support by the European Research Council (ERC) for the ERC Synergy Grant BlackHoleCam under contract no. 610058. JSD acknowledges support by NASA under grant DPR S-15633-Y. Part of this research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration. Joseph Lazio Chief Scientist, Interplanetary Network Directorate Jet Propulsion Laboratory, California Institute of Technology