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Main Authors: Srinivasan, Sankarshana, Thomas, Daniel B, Taylor, Peter L.
Format: Preprint
Published: 2024
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Online Access:https://arxiv.org/abs/2409.06569
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author Srinivasan, Sankarshana
Thomas, Daniel B
Taylor, Peter L.
author_facet Srinivasan, Sankarshana
Thomas, Daniel B
Taylor, Peter L.
contents Stage IV large scale structure surveys are promising probes of gravity on cosmological scales. Due to the vast model-space in the modified gravity literature, model-independent parameterisations represent useful and scalable ways to test extensions of $Λ$CDM. In this work we use a recently validated approach of computing the non-linear $3\times 2$pt observables in modified gravity models with a time-varying effective gravitational constant $μ$ and a gravitational slip $η$ that is binned in redshift to produce Fisher forecasts for an LSST Y10-like survey. We also include in our modelling an effective nulling scheme for weak-lensing by applying the BNT transformation that localises the weak-lensing kernel enabling well-informed scale cuts. We show that the combination of improved non-linear modelling and better control of the scales that are modelled/cut yields high precision constraints on the cosmological and modified gravity parameters. We find that 4 redshift bins for $μ$ of width corresponding to equal incremental $Λ$CDM growth is optimal given the state-of-the-art modelling and show how the BNT transformation can be used to mitigate the impact of small-scale systematic effects, such as baryonic feedback.
format Preprint
id arxiv_https___arxiv_org_abs_2409_06569
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Cosmological gravity on all scales IV: 3x2pt Fisher forecasts for pixelised phenomenological modified gravity
Srinivasan, Sankarshana
Thomas, Daniel B
Taylor, Peter L.
Cosmology and Nongalactic Astrophysics
General Relativity and Quantum Cosmology
Stage IV large scale structure surveys are promising probes of gravity on cosmological scales. Due to the vast model-space in the modified gravity literature, model-independent parameterisations represent useful and scalable ways to test extensions of $Λ$CDM. In this work we use a recently validated approach of computing the non-linear $3\times 2$pt observables in modified gravity models with a time-varying effective gravitational constant $μ$ and a gravitational slip $η$ that is binned in redshift to produce Fisher forecasts for an LSST Y10-like survey. We also include in our modelling an effective nulling scheme for weak-lensing by applying the BNT transformation that localises the weak-lensing kernel enabling well-informed scale cuts. We show that the combination of improved non-linear modelling and better control of the scales that are modelled/cut yields high precision constraints on the cosmological and modified gravity parameters. We find that 4 redshift bins for $μ$ of width corresponding to equal incremental $Λ$CDM growth is optimal given the state-of-the-art modelling and show how the BNT transformation can be used to mitigate the impact of small-scale systematic effects, such as baryonic feedback.
title Cosmological gravity on all scales IV: 3x2pt Fisher forecasts for pixelised phenomenological modified gravity
topic Cosmology and Nongalactic Astrophysics
General Relativity and Quantum Cosmology
url https://arxiv.org/abs/2409.06569