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We introduce an emulator approach to predict the non-linear matter power spectrum for broad classes of beyond-$\Lambda$CDM cosmologies, using only a suite of $\Lambda$CDM $N$-body simulations. By including a range of suitably modified…

Cosmology and Nongalactic Astrophysics · Physics 2019-10-02 Benjamin Giblin , Matteo Cataneo , Ben Moews , Catherine Heymans

We present a new power spectrum emulator named EuclidEmulator that estimates the nonlinear correction to the linear dark matter power spectrum. It is based on a spectral decomposition method called polynomial chaos expansion. All steps in…

A major aim of cosmological surveys is to test deviations from the standard $\Lambda$CDM model, but the full scientific value of these surveys will only be realised through efficient simulation methods that keep up with the increasing…

Cosmology and Nongalactic Astrophysics · Physics 2024-12-06 Yash Gondhalekar , Sownak Bose , Baojiu Li , Carolina Cuesta-Lazaro

Stage IV surveys like LSST and Euclid present a unique opportunity to shed light on the nature of dark energy. However, their full constraining power cannot be unlocked unless accurate predictions are available at all observable scales.…

Cosmology and Nongalactic Astrophysics · Physics 2025-01-30 Daniela Saadeh , Kazuya Koyama , Xan Morice-Atkinson

Testing a subset of viable cosmological models beyond General Relativity (GR), with implications for cosmic acceleration and the Dark Energy associated with it, is within the reach of Rubin Observatory Legacy Survey of Space and Time (LSST)…

Cosmology and Nongalactic Astrophysics · Physics 2021-06-16 Nesar Ramachandra , Georgios Valogiannis , Mustapha Ishak , Katrin Heitmann

In order to probe modifications of gravity at cosmological scales, one needs accurate theoretical predictions. N-body simulations are required to explore the non-linear regime of structure formation but are very time consuming. In this…

Cosmology and Nongalactic Astrophysics · Physics 2024-10-24 Iñigo Sáez-Casares , Yann Rasera , Baojiu Li

Model-independent tests of gravity with cosmology are important when testing extensions to the standard cosmological model. To maximise the impact of these tests one requires predictions for the matter power spectrum on non-linear scales.…

Cosmology and Nongalactic Astrophysics · Physics 2024-04-18 Sankarshana Srinivasan , Daniel B Thomas , Richard Battye

In order to constrain ultra light dark matter models with current and near future weak lensing surveys we need the predictions for the non-linear dark matter power-spectrum. This is commonly extracted from numerical simulations or from…

Cosmology and Nongalactic Astrophysics · Physics 2025-10-15 Dennis Fremstad , Hans A. Winther

We present a field-level reaction framework to emulate the nonlinear effects of screened modified gravity on the cosmic web. This approach is designed to enable field-level inference with data from Stage IV cosmological surveys. Building on…

Cosmology and Nongalactic Astrophysics · Physics 2025-09-22 Daniela Saadeh , Kazuya Koyama , Xan Morice-Atkinson

We consider cosmological models in which dark matter feels a fifth force mediated by the dark energy scalar field, also known as coupled dark energy. Our interest resides in estimating forecasts for future surveys like Euclid when we take…

Cosmology and Nongalactic Astrophysics · Physics 2016-09-02 Santiago Casas , Luca Amendola , Marco Baldi , Valeria Pettorino , Adrian Vollmer

Upcoming galaxy surveys will bring a wealth of information about the clustering of matter, but modeling small-scale structure beyond $\Lambda$CDM remains computationally challenging. While accurate N-body emulators exist to model the matter…

Cosmology and Nongalactic Astrophysics · Physics 2026-04-10 João Rebouças , Victoria Lloyd , Jonathan Gordon , Guilherme Brando , Vivian Miranda

The spatial curvature ($\Omega_K$) of the Universe is one of the most fundamental quantities that could give a link to the early universe physics. In this paper we develop an approximate method to compute the nonlinear matter power…

Cosmology and Nongalactic Astrophysics · Physics 2022-10-19 Ryo Terasawa , Ryuichi Takahashi , Takahiro Nishimichi , Masahiro Takada

We present methods for emulating the matter power spectrum by combining information from cosmological $N$-body simulations at different resolutions. An emulator allows estimation of simulation output by interpolating across the parameter…

Cosmology and Nongalactic Astrophysics · Physics 2021-11-17 Ming-Feng Ho , Simeon Bird , Christian R. Shelton

We propose an alternative approach to the construction of fitting functions to the nonlinear matter power spectrum extracted from $N$-body simulations based on the relative matter power spectrum $\delta(k,a)$, defined as the fractional…

Cosmology and Nongalactic Astrophysics · Physics 2020-03-18 Steen Hannestad , Yvonne Y. Y. Wong

The growth of large-scale structure, together with the geometrical information of cosmic expansion history and cosmological distances, can be used to obtain constraints on the spatial curvature of the universe that probes the early universe…

Cosmology and Nongalactic Astrophysics · Physics 2023-10-23 Ryo Terasawa , Ryuichi Takahashi , Takahiro Nishimichi , Masahiro Takada

We compare and validate COLA (COmoving Lagrangian Acceleration) simulations against existing emulators in the literature, namely Bacco and Euclid Emulator 2. Our analysis focuses on the non-linear response function, i.e., the ratio between…

Cosmology and Nongalactic Astrophysics · Physics 2022-09-28 Guilherme Brando , Bartolomeo Fiorini , Kazuya Koyama , Hans A. Winther

Model-independent constraints on modified gravity models hitherto exist mainly on linear scales. A recently developed formalism presented a consistent parameterisation that is valid on all scales. Using this approach, we perform…

Cosmology and Nongalactic Astrophysics · Physics 2021-06-15 Sankarshana Srinivasan , Daniel B Thomas , Francesco Pace , Richard Battye

Galaxy surveys are an important probe for superimposed oscillations on the primordial power spectrum of curvature perturbations, which are predicted in several theoretical models of inflation and its alternatives. In order to exploit the…

Cosmology and Nongalactic Astrophysics · Physics 2020-04-27 Mario Ballardini , Riccardo Murgia , Marco Baldi , Fabio Finelli , Matteo Viel

Testing gravity and the concordance model of cosmology, $\Lambda$CDM, at large scales is a key goal of this decade's largest galaxy surveys. Here we present a comparative study of dark matter power spectrum predictions from different…

The mysterious nature of the dark sector of the $\Lambda$CDM model is one of the main motivators behind the study of alternative cosmological models. A central quantity of interest for these models is the matter power spectrum, which…

Cosmology and Nongalactic Astrophysics · Physics 2024-06-11 Renate Mauland , Hans A. Winther , Cheng-Zong Ruan
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