Kinetic Sunyaev Zeldovich effect in an anisotropic CMB model: measuring low multipoles of the CMB at higher redshifts using intensity and polarization spectral distortions [CEA]

We present a novel mathematical formalism that allows to easily compute the expected kinetic Sunyaev Zeldovich (kSZ) signal in intensity and polarization due to an anisotropic primordial Cosmic Microwave Background (CMB). We show that, in the direction of moving clusters, low CMB multipoles impose intensity and polarization spectral distortions with different frequency dependences. The polarization signal primarily probes the quadrupole moment of the CMB, with a significant contribution from the primordial dipole and octupole moments. For a typical cluster velocity of 1000 km/s, corrections to the standard, non-moving cluster quadrupole-induced polarization are of the order of 2-10% between 200-600 GHz, and depend on cluster’s position on the sky, velocity magnitude and direction of motion. At 300 GHz, the sky area where the correction is greater than 10% is about 20%, although close to the galactic plane. The sky locations where maximum and minimum polarization signals are expected for moving clusters vary with frequency of observation. The distinct frequency and spatial dependences of the polarization induced by the primordial dipole and octupole can be exploited to measure them despite other physical effects and foregrounds. Contrary to polarization, intensity distortions are affected by all the CMB multipoles, so they cannot be readily used to probe the low multipoles at higher redshifts. However, correlations between intensity and polarization signals can be used to enhance the signal to noise ratio for the measurements of the primordial dipole, quadrupole and octupole.

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S. Yasini and E. Pierpaoli
Tue, 10 May 16

Comments: 22 pages, 10 figures