Astro2010 Decadal Survey Whitepaper: Coordinated Science in the
  Gravitational and Electromagnetic Skies
  It is widely expected that the coming decade will witness the first direct
detection of gravitational waves (GWs). The ground-based LIGO and Virgo GW
observatories are being upgraded to advanced sensitivity, and are expected to
observe a significant binary merger rate. The launch of The Laser
Interferometer Space Antenna (LISA) would extend the GW window to low
frequencies, opening new vistas on dynamical processes involving massive (M >~
10^5 M_Sun) black holes. GW events are likely to be accompanied by
electromagnetic (EM) counterparts and, since information carried
electromagnetically is complementary to that carried gravitationally, a great
deal can be learned about an event and its environment if it becomes possible
to measure both forms of radiation in concert. Measurements of this kind will
mark the dawn of trans-spectral astrophysics, bridging two distinct spectral
bands of information. The aim of this whitepaper is to articulate future
directions in both theory and observation that are likely to impact broad
astrophysical inquiries of general interest. What will EM observations reflect
on the nature and diversity of GW sources? Can GW sources be exploited as
complementary probes of cosmology? What cross-facility coordination will expand
the science returns of gravitational and electromagnetic observations?
