Cosmology from the kinetic polarized Sunyaev Zel'dovich effect

Abstract

The cosmic microwave background (CMB) photons that scatter off free electrons in the large-scale structure induce a linear polarization pattern proportional to the remote CMB temperature quadrupole observed in the electrons' rest frame. The associated blackbody polarization anisotropies are known as the polarized Sunyaev Zel'dovich (pSZ) effect. Relativistic corrections to the remote quadrupole field give rise to a non-blackbody polarization anisotropy proportional to the square of the transverse peculiar velocity field; this is the kinetic polarized Sunyaev Zel'dovich (kpSZ) effect. In this paper, we forecast the ability of future CMB and galaxy surveys to detect the kpSZ effect, finding that a statistically significant detection is within the reach of planned experiments. We further introduce a quadratic estimator for the square of the peculiar velocity field based on a galaxy survey and CMB polarization. Finally, we outline how the kpSZ effect is a probe of cosmic birefringence and primordial non-Gaussianity, forecasting the reach of future experiments.

Probing cosmic birefringence with polarized Sunyaev-Zel’dovich tomography

“…While this signal is around an order-of-magnitude smaller than the pSZ signal we consider here, it can still be used to probe fundamental physics as demonstrated in Ref. [71]. Nevertheless, we expect the kinetic pSZ to not be a significant source of confusion or bias for the pSZ analysis since it has a frequency dependence different than the CMB black-body and can potentially be removed from maps via ILC-cleaning.…”

“…Note that here we have only considered the 'primary' contributions to the temperature quadrupole that are leading order in perturbation theory, omitting the kinetic pSZ that is recently discussed in Ref. [71]. The pSZ signal gets a contribution from the transverse peculiar velocities of electrons which induce a non-zero quadrupole at the electron rest frame that is second order in velocity.…”

E and B modes of the CMB y-type distortions: polarised kinetic Sunyaev-Zeldovich effect from the reionisation and post-reionisation eras

“…We want to mention that as we were completing this work another paper on the pkSZ effect appeared on arXiv [53]. They also studied the polarisation signal from reionisation, but their work was focused on using this signal to probe cosmic birefringence and non-Gaussianity rather than reionisation.…”