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Speaker |
Cabass, Giovanni |
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Coauthors |
Cabass, Giovanni; Gerbino, Martina; Giusarma, Elena; Melchiorri, Alessandro; Pagano, Luca; Salvati, Laura |
| Talk Title |
Constraints on the Early and Late Integrated Sachs-Wolfe effects after Planck 2015 |
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Abstract |
The Integrated Sachs-Wolfe (ISW) effect predicts the production of additional anisotropies in the Cosmic Microwave Background (CMB) due to time variation of the gravitational potential when the expansion of the universe is not matter dominated. The ISW effect is then expected in the early universe, due to the presence of relativistic particles around recombination, and in the late universe, when dark energy starts to dominate the expansion. The late-time ISW effect can be used to distinguish between the standard LambdaCDM universe and models that try to explain the present day acceleration through modifications of gravity: in fact modified gravity scenarios predict a suppression of the correlations between ISW and the density contrast observed by surveys. Deviations from the standard picture can be parametrized by A(EISW) and A(LISW), which rescale the overall amplitude of the early and late ISW effects (the standard scenario being A(EISW) and A(LISW) equal to 1). We analyze the constraints on the two parameters in the LambdaCDM + A(ISW) extension of the standard cosmological model, and discuss the stability of our result in the case of a extra relativistic energy component parametrized by the effective neutrino number N(eff) and of a CMB lensing amplitude A(LENS). We then discuss what are the possible implications of these results for Modified Gravity scenarios. |
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