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Todays Colloquium: Foregrounds for future cosmology radio surveys

Submitter: Clive Dickinson
Description: Radio astronomy is now set to revolutionize cosmology (again) in a number of ways:
  • by measuring the CMB polarization we aim to detect gravitational waves in the Universe to constrain models of inflation
  • by observing Baryon Acoustic Oscillations (BAOs) at moderate redshift to measure the expansion of the Universe at late times to constrain dark energy
  • by measuring the Epoch of Reionization (EoR) at high redshift via the redshifted 21cm HI line to investigate structure formation at the earliest times.

    All of these goals are likely to be achievable over the next few years but will be limited by a common enemy - foregrounds! The intervening emission from our own Galaxy and external galaxies dominate these faint cosmological signals and must be removed.

    In this talk I review foregrounds for both CMB and low frequency radio astronomy surveys. Along the way, I will show interesting new astrophysical results that come about from carrying out deep radio surveys such as the identification of electric dipole radiation from spinning dust grains. I will also introduce a single-dish concept, the BINGO experiment, that may allow the first detection of BAOs at radio wavelengths.

    The image shows the radio sky at 408 MHz (Haslam et al. 1981, 1982). The observed structures in the sky are dominated by diffuse synchrotron emission from our own Galaxy as well as from external galaxies. This is all foreground contamination for cosmologists, who are interested in accurately measuring the cosmic microwave background (CMB) or the large-scale structure traced by the 21cm HI line.
  • Copyright: C. G. T. Haslam; ESO
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