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10GHz sky survey to probe inflation with CMB polarization Tanimura, Hideki

Abstract

The fluctuations in the cosmic microwave background(CMB) contain a lot of information on the history and composition of our universe. In particular, the rich detail about our early universe is included in the angular power spectra of the CMB fluctuations, which constrains the cosmological parameters in current models of the universe. The latest cosmological data strongly support an inflationary Lambda CDM cosmology with a minimal six parameters to describe our universe. The next challenge in cosmology is to probe the physics of the inflationary period by looking for the signature of primordial gravitational waves in the polarized CMB. CMB polarization was generated at last scattering by scalar and tensor perturbations in the primordial fluid. The tensor perturbations are produced by the stretching of space-time by gravitational wave fluctuations, while scalar perturbations are produced by density fluctuations in the primordial fluid. The ratio of the tensor to scalar perturbation amplitude, r, is a key tracer of the physics of the inflationary epoch, which is deeply connected to the energy scale of inflation in a standard inflationary model. A local quadrupole anisotropy in the radiation field at the time of decoupling causes the linear polarization in CMB through Thomson scattering by electrons. The CMB polarization can be decomposed into two rotationally invariant quantities, called E and B. The CMB B-mode is a direct tracer of the tensor perturbations caused by gravitational waves in the inflationary period of the universe. Thus, the detection of B-mode has currently been dubbed the ''smoking gun'' of inflation. However, the galactic foreground emissions also have much stronger E- and B-modes polarization. We intend to produce half-sky maps of total intensity and linear polarization at 10 GHz. This data would probe galactic synchrotron emission and also can help constrain the so-called anomalous emission. Therefore, the maps can be used with other surveys such as WMAP and Planck to subtract galactic foreground emissions and obtain more precise CMB data. In addition, the data will give us information about galactic emission components such as synchrotron, free-free, thermal dust and anomalous emission in the microwave range.

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