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Title: Fast generation of dark matter halo catalogs with modified gravity

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Abstract: Future generations of large scale structure surveys will measure the clustering of matter with high precision, yielding tight constraints on cosmological parameters and allowing to investigate models that go beyond the standard LCDM one. To make predictions both for the standard model and its extensions, and possibly test theories of gravity alternative to General Relativity, large sets of N-body simulations are needed. Approximate methods are one possible alternative to computationally expensive N-body simulations, being able to generate distributions of dark matter halos in a fast way with minor compromises on the accuracy. One code that allows to do that is the PINOCCHIO software. I will present the approach taken to extend it to modified gravity models (with a particular focus on f(R) gravity), which includes the development of a new way to compute second order Lagrangian displacements in presence of modified gravity, as well as a reformulation of ellipsoidal collapse. A comparison to N-body simulations confirms that our extended code allows to recover halo abundances and clustering statistics up to mildly non-linear scales with the same accuracy obtained for the standard model, making PINOCCHIO a valuable tool for constraining beyond-LCDM models with forthcoming surveys.

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