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Mar 2
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Hyunbae Park
University of Texas at Austin
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"Revisiting Transverse Peculiar Momentum Power Spectrum in the Non-linear Regime: Implications for the Post-reionization Kinetic Sunyaev-Zel'dovich Effect"
The temperature anisotropy of the cosmic microwave background (CMB) which result from undergoing its scattering by intergalactic free electrons called the kinetic Sunyaev-Zel`dovish (kSZ) effect, is given by the component of the momentum field of the ionized gas in Fourier space transverse to the wavevector of each mode. During the post-reionization epoch where the gas is fully ionized to a good approximation, the main uncertainty is in non-linearity in the density field and the velocity field. We revisit the current non-linear model for the transverse momentum power spectrum that is the key ingredient in computing the kSZ signal in CMB. We focus our attention on the forth order term composed of two density and two velocity fields, , which is dominant over other terms for the transverse mode. We point out that previous works modeling the non-linear power spectrum only took into account the unconnected moment of the forth order term: _uc = ++. In the non-linear regime, however, there is non-zero contribution from the connected term, _c = - _uc. Using out N-body simulation, we first confirm that the current model successfully models the unconnected moment with a high accuracy. Then, we investigate the contribution from the connected moment using the Eulerian perturbation theory as well as our N-body simulation. At z = 0, the next-to-leading connected moment gives ~10% of additional power at the quasi-nonlinear and non-linear scales (k <~ 0.1 h/Mpc). At quasi-nonlinear scales (0.1 <~ k <~ 0.3 h/Mpc ), the next-to-leading order connect moment precisely recovers compensates for the excess in the simulation that the unconnected expression cannot explain. However, the contributing wavenumber is mostly in the highly non-linear regime ( k >~ 0.3 h/Mpc), where the simulation suggests higher contribution from the connected moment than the next-to-leading order expression does. Simulation result at z>=0.5 suggests ~ 10 % of additional contribution from the connected moment, which would lead to ~ 20 % less budget for the reionization kSZ signal.
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Mar 23
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Monday 23 March, 2015, 3:30 p.m.
JOINT THEORETICAL ASTROPHYSICS/PHYSICS THEORY GROUP SEMINAR:
Dr. Marcello Musso, University of Pennsylvania,
"Random Walks in the Sky: Theoretical Halo Statistics for Cosmology", RLM 15.216B.
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