Mapping the Galactic Center with Gravitational Wave Measurements using
  Pulsar Timing
  We examine the nHz gravitational wave (GW) foreground of stars and black
holes (BHs) orbiting SgrA* in the Galactic Center. A cusp of stars and BHs
generates a continuous GW spectrum below 40 nHz; individual BHs within 1 mpc to
SgrA* stick out in the spectrum at higher GW frequencies. The GWs and
gravitational near-field effects can be resolved by timing pulsars within a few
pc of this region. Observations with the Square Kilometer Array (SKA) may be
especially sensitive to intermediate mass black holes (IMBHs) in this region,
if present. A 100ns-10mus timing accuracy is sufficient to detect BHs of mass
1000 Msun with pulsars at distance 0.1-1 pc in a 3 yr observation baseline.
Unlike electromagnetic imaging techniques, the prospects for resolving
individual objects through GW measurements improve closer to SgrA*, even if the
number density of objects increases inwards steeply. Scattering by the
interstellar medium will pose the biggest challenge for such observations.
