Snowmass2021 Cosmic Frontier White Paper: Observational Facilities to
  Study Dark Matter
  We present an overview of future observational facilities that will
significantly enhance our understanding of the fundamental nature of dark
matter. These facilities span a range of observational techniques including
optical/near-infrared imaging and spectroscopy, measurements of the cosmic
microwave background, pulsar timing, 21-cm observations of neutral hydrogen at
high redshift, and the measurement of gravitational waves. Such facilities are
a critical component of a multi-pronged experimental program to uncover the
nature of dark matter, while often providing complementary measurements of dark
energy, neutrino physics, and inflation.
