Cluster formation and the Sunyaev–Zel'dovich power spectrum in modified gravity: the case of a phenomenologically extended DGP model |
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| Authors: | Tsutomu Kobayashi Hiroyuki Tashiro |
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| Institution: | Department of Physics, Waseda University, Okubo 3-4-1, Shinjuku, Tokyo 169-8555, Japan;Institut d'Astrophysique Spatiale (IAS), UniversitéParis-Sud 11 and CNRS, F-91405 Orsay, France |
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| Abstract: | We investigate the effect of modified gravity on cluster abundance and the Sunyaev–Zel'dovich (SZ) angular power spectrum. Our modified gravity is based on a phenomenological extension of the Dvali–Gabadadze–Porrati model which includes two free parameters characterizing deviation from Λ cold dark matter cosmology. Assuming that Birkhoff's theorem gives a reasonable approximation, we study the spherical collapse model of structure formation and show that while the growth function changes to some extent, modified gravity gives rise to no significant change in the linear density contrast at collapse time. The growth function is enhanced in the so called normal branch, while in the 'self-accelerating' branch it is suppressed. The SZ angular power spectrum is computed in the normal branch, which allows us to put observational constraints on the parameters of the modified gravity model using small scale cosmic microwave background observation data. |
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| Keywords: | cosmology: theory large-scale structure of universe |
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