Seminar 06.05.2013 – Using Planck’s secondary temperature anisotropies of the Cosmic Microwave Background to constrain Dark Energy
Carlos Hernández Monteagudo
Centro de Estudios de Física del Cosmos de Aragón
Facultat de Física (UB)
Sala de Graus Eduard Fontseré
I will describe the constraints obtained by the Cosmic Microwave Background (CMB) observations of the Planck mission from the Integrated Sachs-Wolfe (ISW) and the kinetic Sunyaev-Zel'dovich (kSZ) effects. The ISW effect is the blue-shift experienced by CMB photons as they propagate across large scale gravitational potential wells. Dark energy induces a decrease of potential wells with time, implying an energy gain (or net blue-shift) of photons moving through them. By cross correlating CMB maps with probes of large scale gravitational potential wells, we attempt to extract signatures of the ISW effect in Planck CMB data. At the same time, if the apparent accelerated expansion is caused by the presence of a giant (size ~ 1 Gpc) void, then structure in this expanding underdense region should show high peculiar velocities with respect to the CMB, which would induce a large kSZ effect. By setting strong constraints on these peculiar velocities from limits on the kSZ effect, Planck is able to rule out a vast family of these inhomogeneous cosmological models, confirming that the observed expansion acceleration is of a universal and homogeneous nature.