Cosmic Microwave Background Discipline Working

Executive summary

Group Chair: Matt Dobbs, McGill University

In this report the Cosmic Microwave Background (CMB) Working Group provides a roadmap and recommendations for the next decade of CMB space astronomy in Canada.

Key Science

How did the Universe begin? Inflation is the leading theoretical paradigm for describing the first moments after the Big Bang. The 'smoking gun' prediction of favoured inflationary models is the existence of an inflationary gravity wave background that imprints a signature on the CMB as a faint curl-component to the polarization pattern on large angular scales. Its detection would be a direct probe of physics at the very highest energies. The primary objective for the decadal roadmap described in this document is a measurement of the CMB-polarization that will allow for the detection of the inflationary gravity wave signature, or an upper bound on its energy scale. These measurements will additionally provide tests of Einstein's gravity on large scales, information about new particles or forces, and possibly new insight on Dark Energy. They will enable anew window on the Universe, creating new knowledge that will continue Canada's tradition of international excellence in this field.

Canadian Expertise

The CMB community in Canada is characterized by a high level of expertise in the Universities, with a strong commitment to training of graduate students. Canadians have established themselves as world leaders in detector electronics, data analysis and associated software, and the design/integration/operation of stratospheric balloon telescopes. For example, experiments around the world using the current generation of more than a couple hundred bolometric detectors share one thing in common: their readout electronics were provided by members of the Canadian CMB community, and Canadians partner in the scientific return of these projects. Canadian academics have begun industrial partnerships to transfer this technology. Trainees are incorporated into every element of the development and operation of experiments, resulting in broadly trained individuals with unparalleled experience in the development and analysis of scientific instruments.

Decadal Roadmap

This Working Group anticipates that there will be one or two more generations of suborbital and custom ground-based experiments leading to a major satellite mission to map the polarization of the CMB over the whole sky with sufficient angular resolution to study the gravitational lensing signal and with sensitivity at least an order of magnitude better than any currently designed experiment. As such, the Canadian CMB community foresees significant involvement with the following missions over the next decade:

  • Planck Satellite, launching in 2009
  • EBEX and SPIDER Balloon-borne polarimeters, with science flights from 2009-2013. We expect at least one additional sub-orbital mission to develop this decade.
  • An international partnership for a purpose-built CMB Polarization satellite for launch towards the end of the next decade.

This program must be coupled with a rigorous commitment to technology development and personnel training from both the community and funding agencies. This space roadmap will benefit from the community's extensive involvement with ground-based projects.


  • CSA should continue to fund sub-orbital projects on merit through the Small Missions or similar program. The community and the Agency should anticipate another generation of sub-orbital CMB missions after the currently funded set.
  • To fund missions for their full lifetime, including data analysis, as long as they demonstrate through periodic peer review that they are scientifically productive. This is especially important for Planck, but it is important for all CMB missions. An expanded SSEP-style for funding post-doctoral fellows would suffice, providing adequate funding is made available.
  • Provide continuity of funding for technology development and training of highly qualified personnel, possibly through a new CREATE-like program. Fund technology development within the SSEP program.
  • Fund participation as a full partner in an international effort for a mission which will produce ambitious full sky polarization maps of the CMB. The Working Group will be active in the CASCA Long Range Planning exercise to assure that there is broad community support for this mission.