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We implement an adaptation of the COLA approach, a hybrid scheme that combines Lagrangian perturbation theory with an N-body approach, to model non-linear collapse in chameleon and symmetron modified gravity models. Gravitational screening…

Cosmology and Nongalactic Astrophysics · Physics 2017-05-30 Georgios Valogiannis , Rachel Bean

We study the effect of two Modified Gravity (MG) theories, $f(R)$ and nDGP, on three probes of large-scale structure, the real space power spectrum estimator $Q_0$, bispectrum and voids, and validate fast approximate COLA simulations…

Cosmology and Nongalactic Astrophysics · Physics 2022-12-28 Bartolomeo Fiorini , Kazuya Koyama , Albert Izard

We present a general parallelized and easy-to-use code to perform numerical simulations of structure formation using the COLA (COmoving Lagrangian Acceleration) method for cosmological models that exhibit scale-dependent growth at the level…

Cosmology and Nongalactic Astrophysics · Physics 2017-08-09 Hans A. Winther , Kazuya Koyama , Marc Manera , Bill S. Wright , Gong-Bo Zhao

We test the convergence of fast simulations based on the COmoving Lagrangian Acceleration (COLA) method for predictions of the matter power spectrum, specialising our analysis in the redshift range $1 \le z \le 1.65$, relevant to…

Cosmology and Nongalactic Astrophysics · Physics 2023-11-21 Bartolomeo Fiorini , Kazuya Koyama , Tessa Baker

This thesis introduces a set of methods for testing models of modified gravity using galaxy clusters. In particular, a technique for constraining models with a chameleon screening is introduced. In addition, the outlined technique is…

Cosmology and Nongalactic Astrophysics · Physics 2020-11-18 Andrius Tamosiunas

We investigate the viability of producing galaxy mock catalogues with COmoving Lagrangian Acceleration (COLA) simulations in Modified Gravity (MG) models employing the Halo Occupation Distribution (HOD) formalism. In this work, we focus on…

Cosmology and Nongalactic Astrophysics · Physics 2021-09-20 Bartolomeo Fiorini , Kazuya Koyama , Albert Izard , Hans A. Winther , Bill S. Wright , Baojiu Li

Accurate predictions for the non-linear matter power spectrum are needed to confront theory with observations in current and near future weak lensing and galaxy clustering surveys. We propose a computationally cheap method to create an…

Cosmology and Nongalactic Astrophysics · Physics 2020-01-01 Hans Winther , Santiago Casas , Marco Baldi , Kazuya Koyama , Baojiu Li , Lucas Lombriser , Gong-Bo Zhao

Modifications of general relativity provide an alternative explanation to dark energy for the observed acceleration of the universe. We review recent developments in modified gravity theories, focusing on higher dimensional approaches and…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-18 Bhuvnesh Jain , Justin Khoury

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

The theoretical basis of dark energy remains unknown and could signify a need to modify the laws of gravity on cosmological scales. In this study we investigate how the clustering and motions of galaxies can be used as probes of modified…

Cosmology and Nongalactic Astrophysics · Physics 2023-01-10 Stuart Lyall , Chris Blake , Ryan Turner , Rossana Ruggeri , Hans Winther

The standard paradigm of cosmology assumes General Relativity (GR) is a valid theory for gravity at scales in which it has not been properly tested. Developing novel tests of GR and its alternatives is crucial if we want to give strength to…

Cosmology and Nongalactic Astrophysics · Physics 2021-03-22 Claudio Llinares

We use N-body simulations to study the statistics of massive halos and redshift space distortions for theories with a standard \Lambda CDM expansion history and a galileon-type scalar field. The extra scalar field increases the…

Cosmology and Nongalactic Astrophysics · Physics 2013-10-30 Mark Wyman , Elise Jennings , Marcos Lima

In this paper we present preliminary results from cosmological simulations of modified gravity in the dark matter sector. Our results show improvements over standard cold dark matter cosmology. The abundance of low-mass haloes in the…

Astrophysics · Physics 2008-07-08 Wojciech A. Hellwing

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…

In the last two decades, Modified Gravity (MG) models have been proposed to explain the accelerated expansion of the Universe. However, one of the main difficulties these theories face is that they must reduce to General Relativity (GR) at…

General Relativity and Quantum Cosmology · Physics 2021-10-27 Alejandro Aviles

This paper is a pedagogical introduction to models of gravity and how to constrain them through cosmological observations. We focus on the Horndeski scalar-tensor theory and on the quantities that can be measured with a minimum of…

Cosmology and Nongalactic Astrophysics · Physics 2020-01-27 Luca Amendola , Dario Bettoni , Ana Marta Pinho , Santiago Casas

Stage-IV surveys will enable unprecedented tests of gravity on cosmological scales. However, assuming General Relativity in the analysis of large-scale structure could introduce systematic biases if gravity deviates from GR at these scales.…

Cosmology and Nongalactic Astrophysics · Physics 2025-11-27 Marc Alemany-Gotor , Cristian Viglione , Pablo Fosalba , Isaac Tutusaus

We review recent progress in the construction of modified gravity models as alternatives to dark energy as well as the development of cosmological tests of gravity. Einstein's theory of General Relativity (GR) has been tested accurately…

Cosmology and Nongalactic Astrophysics · Physics 2016-03-24 Kazuya Koyama

In this series of papers we present an emulator-based halo model for the non-linear clustering of galaxies in modified gravity cosmologies. In the first paper, we present emulators for the following halo properties: the halo mass function,…

We elucidate the importance of the consistent treatment of gravity-model specific non-linearities when estimating the growth of cosmological structures from redshift space distortions (RSD). Within the context of standard perturbation…

Cosmology and Nongalactic Astrophysics · Physics 2017-07-26 Benjamin Bose , Kazuya Koyama , Wojciech A. Hellwing , Gong-Bo Zhao , Hans A. Winther
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