Cosmology in front of the background: studying the growth of structure
  at CMB wavelengths
  Canada has thriving communities in CMB (cosmic microwave background) studies,
cosmology and submillimetre (submm) astronomy, with involvement in many
facilities that featured prominently in previous Astronomy Long Range Plans.
The standard cosmological model continues to be well fit using a small number
of parameters. No one expects this model to be complete and so we need to
continue to challenge it with data; moreover, it does not explain how galaxies
and other structures form. So, how do we improve the precision of our
understanding of structure formation within this model? Wavelengths from the
microwave to the submm will be particularly fruitful for answering this
question. That's because, in addition to the CMB anisotropies, there are other
signals that can be extracted from large maps at these wavelengths -
particularly the cosmic infrared and submm backgrounds, the thermal and kinetic
Sunyaev-Zeldovich effects, and CMB lensing. Such signals carry a wealth of
information about the cosmological model, as well as how dust, gas and
star-formation evolve within dark-matter halos. Cross-correlations between
these signals and those coming from the radio, optical and X-ray surveys, will
provide even more information. Canadians are already members of teams for
several related facilities and are working to be involved in others. In order
for Canada to be fully engaged in exploiting the detailed information coming
from these cosmological signatures, it is crucial that we find the resources to
participate competitively in a combination of projects currently being planned.
Examples include CMB-S4, CCAT-prime, AtLAST, a new camera for JCMT, balloon
projects such as BFORE and a future ambitious CMB satellite.
