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## Abstract / Description of output

Modelling nonlinear structure formation is essential for current and
forthcoming cosmic shear experiments. We combine the halo model reaction
formalism, implemented in the REACT code, with the COSMOPOWER machine
learning emulation platform, to develop and publicly release
REACTEMU-FR, a fast and accurate nonlinear matter power spectrum
emulator for f(R)
gravity with massive neutrinos. Coupled with the state-of-the-art
baryon feedback emulator BCEMU, we use REACTEMU-FR to produce Markov
Chain Monte Carlo forecasts for a cosmic shear experiment with typical
Stage IV specifications. We find that the inclusion of highly nonlinear
scales (multipoles between 1500≤ℓ≤5000)
only mildly improves constraints on most standard cosmological
parameters (less than a factor of 2). In particular, the necessary
modelling of baryonic physics effectively damps most constraining power
on the sum of the neutrino masses and modified gravity at ℓ≳1500.
Using an approximate baryonic physics model produces mildly improved
constraints on cosmological parameters which remain unbiased at the 1σ-level, but significantly biases constraints on baryonic parameters at the >2σ-level.

Original language | English |
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Pages (from-to) | 1-18 |

Number of pages | 18 |

Journal | The Open Journal of Astrophysics |

Volume | 6 |

DOIs | |

Publication status | Published - 6 Nov 2023 |

## Keywords / Materials (for Non-textual outputs)

- large-scale structure of the Universe
- cosmic shear
- baryon feedback
- massive neutrinos
- f(R) gravity
- cosmology
- statistical methods

## Fingerprint

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