THE IMPACT OF NONLINEAR STRUCTURE FORMATION ON THE POWER SPECTRUM OF TRANSVERSE MOMENTUM FLUCTUATIONS AND THE KINETIC SUNYAEV-ZEL’DOVICH EFFECT

다국어 초록 (Multilingual Abstract)

<P>Cosmological transverse momentum fields, whose directions are perpendicular to Fourier wave vectors, induce temperature anisotropies in the cosmic microwave background via the kinetic Sunyaev-Zel'dovich (kSZ) effect. The transverse momentum power spectrum contains the four-point function of density and velocity fields, <delta delta nu nu >. In the post-reionization epoch, nonlinear effects dominate in the power spectrum. We use perturbation theory and cosmological N-body simulations to calculate this nonlinearity. We derive the next-to-leading order expression for the power spectrum with a particular emphasis on the connected term that has been ignored in the literature. While the contribution from the connected term on small scales (k > 0.1 h Mpc(-1)) is subdominant relative to the unconnected term, we find that its contribution to the kSZ power spectrum at l = 3000 at z < 6 can be as large as ten percent of the unconnected term, which would reduce the allowed contribution from the reionization epoch (z > 6) by twenty percent. The power spectrum of transverse momentum on large scales is expected to scale as k(2) as a consequence of momentum conservation. We show that both the leading and the next-to-leading order terms satisfy this scaling. In particular, we find that both of the unconnected and connected terms are necessary to reproduce k(2).</P>