COLA with scale-dependent growth: applications to screened modified gravity models

We develop perturbation theory approaches to model the marked correlation function constructed to up-weight low density regions of the Universe, which might help distinguish modified gravity models from the standard cosmology model based on general relativity. Working within Convolution Lagrangian Perturbation Theory, we obtain that weighted correlation functions are expressible as double convolution integrals that we approximate using a combination of Eulerian and Lagrangian schemes. We find that different approaches agree within 1% on quasi non-linear scales. Compared with N-body simulations, the perturbation theory is found to provide accurate predictions for the marked correlation function of dark matter fields, dark matter halos as well as Halo Occupation Distribution galaxies down to 30 Mpc/h. These analytic approaches help to understand the degeneracy between the mark and the galaxy bias and find a way to maximize the differences among various cosmological models.

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“…, (A.6) and the second order growth functions, D (2) , are the solutions to equations [31][32][33] (T − A(k))D…”

Section: Discussionmentioning

confidence: 99%

Marked correlation functions in perturbation theory

Avilés

Koyama

Cervantes-Cota

et al. 2020

J. Cosmol. Astropart. Phys.

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“…We can show that the corresponding Fourier transform with respect to q at second order for the specific case of scale-dependent modified gravity without massive neutrinos is [52,58,59]…”

Section: Scale-dependent Modified Gravity Without Massive Neutrinosmentioning

confidence: 99%

COLA with massive neutrinos

Wright

Winther

Koyama

2017

J. Cosmol. Astropart. Phys.

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Abstract. The effect of massive neutrinos on the growth of cold dark matter perturbations acts as a scale-dependent Newton's constant and leads to scale-dependent growth factors just as we often find in models of gravity beyond General Relativity. We show how to compute growth factors for ΛCDM and general modified gravity cosmologies combined with massive neutrinos in Lagrangian perturbation theory for use in COLA and extensions thereof. We implement this together with the grid-based massive neutrino method of Brandbyge and Hannestad in MG-PICOLA and compare COLA simulations to full N-body simulations of ΛCDM and f (R) gravity with massive neutrinos. Our implementation is computationally cheap if the underlying cosmology already has scale-dependent growth factors and it is shown to be able to produce results that match N-body to percent level accuracy for both the total and CDM matter power-spectra up to k 1h/Mpc.

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“…In the previous work (Hu et al 2018), we proposed the screened halo model (CHAM) method for the non-linear power spectrum modelling in the alternatives to the standard ΛCDM scenario. Besides, there also exist some hybrid methods combining higher order perturbation theory with simulations, such as COLA Tassev et al (2013) and its modified version Valogiannis & Bean (2017); Winther et al (2017). Further-more, the recent progresses in the emulator Winther et al (2019) and reaction method Cataneo et al (2019) predict that we are able to approaching 1% level of modelling the non-linear power spectrum for the generic dark energy/modified gravity models.…”

Section: Introductionmentioning

confidence: 99%

Non-linear matter power spectrum without screening dynamics modelling in f(R) gravity

Ruan

Zhang

2020

Monthly Notices of the Royal Astronomical Society

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Halo model is a physically intuitive method for modelling the non-linear power spectrum, especially for the alternatives to the standard ΛCDM models. In this paper, we exam the Sheth-Tormen barrier formula adopted in the previous CHAM method (Hu et al. 2018). As an example, we model the ellipsoidal collapse of top-hat dark matter haloes in f (R) gravity. A good agreement between Sheth-Tormen formula and our result is achieved. The relative difference in the ellipsoidal collapse barrier is less than or equal to 1.6%. Furthermore, we verify that, for F4 and F5 cases of Hu-Sawicki f (R) gravity, the screening mechanism do not play a crucial role in the non-linear power spectrum modelling up to k ∼ 1[h/Mpc]. We compare two versions of modified gravity modelling, namely with/without screening. We find that by treating the effective Newton constant as constant number (G eff = 4/3G N ) is acceptable. The scale dependence of the gravitational coupling is sub-relevant. The resulting spectra in F4 and F5, are in 0.1% agreement with the previous CHAM results. The published code is accelerated significantly. Finally, we compare our halo model prediction with N-body simulation. We find that the general spectrum profile agree, qualitatively. However, via the halo model approach, there exists a systematic under-estimation of the matter power spectrum in the co-moving wavenumber range between 0.3h/Mpc and 3h/Mpc. These scales are overlapping with the transition scales from two halo term dominated regimes to those of one halo term dominated.

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COLA with scale-dependent growth: applications to screened modified gravity models

Cited by 93 publications

References 78 publications

Marked correlation functions in perturbation theory

Marked correlation functions in perturbation theory

COLA with massive neutrinos

Non-linear matter power spectrum without screening dynamics modelling in f(R) gravity

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