Simulation-based clustering to constrain Modified Gravity theories

Carolina Cuesta-Lazaro

 April 2022 - Britgrav

FORGE Collaboration: Christian Arnold, Benjamin Giblin, Joachim Harnois-Deraps, Yan-Chuan Cai, Cesar Hernandez-Aguayo, Chris Davies, Enrique Paillas, Cheng-Zong Ruan and Baojiu Li

Space-time

geometetry

Energy content

Adding new degrees of freedom

  • To the energy content (dynamic) DARK ENERGY
  • To the way space-time geometry reacts to the energy content MODIFIED GRAVITY (FIFTH FORCES)

?

GRAVITATIONAL ACTIONS 

S_{GR}
S_{f(R)}
S_{nDGP}
S_{?}

N-BODY SIMULATIONS

\mathcal{O}(50)

LIKELIHOOD

LARGE SCALE STRUCTURE DATA

DESI,Euclid ...

GRAVITATIONAL ACTIONS 

S_{GR}
S_{f(R)}
S_{nDGP}
S_{?}

N-BODY SIMULATIONS

\mathcal{O}(50)

LIKELIHOOD

LARGE SCALE STRUCTURE DATA

DESI,Euclid ...

DESI

Spectroscopic

30+ million redshifts

Credit: D. Schlegel/Berkeley Lab using data from DESI

EUCLID

Imaging

15,000 square degrees out to redshift z=2

S = \int d^4 x \sqrt{-g} \left(\frac{R + f(R)}{16 \pi G} + \mathcal{L_m} \right)

arxiv:2109.04984

nDGP

Can match expansion to LCDM

Screening mechanisms to pass solar system tests

Do not modify speed of gravitational wave propagation

Need a "cosmological constant"

S = \int d^4 x \sqrt{-g} \left(\frac{R }{16 \pi G} + \mathcal{L}_m \right) + \int d^5 x \sqrt{-g_5} \frac{R_5}{16 \pi G r_c}

f(R)

FORGE: F(R)

BRIDGE: nDGP

H_0r_c
f_{R_0}

More models coming soon!

MG-GLAM x100 faster than MG-Arepo

arxiv:2110.00328

arxiv:2110.00566

arxiv:2109.04984

2-POINT STATISTICS

arxiv:2109.04984

Credit: https://cs231n.github.io/convolutional-networks/

\hat{O}(k)
\mathcal{L} = \frac{1}{n} \sum |\hat{O}(k) - O(k)|
\Omega_m
|f(R)|
h
\sigma_8

FORGE collaboration (in prep)

Harnois-Deraps et al (in prep)

C^{ij}_\ell = \int_0^{\chi_H} d \chi \frac{q^i(\chi) q^j(\chi)}{\chi^2} P_{mm}\left( \frac{\ell + 1/2}{\chi}, z(\chi) \right)

Mimicking Euclid

Environment dependent clustering

 

  • O(50) N-body simulations -> sub-percent accurate predictions for two point observables -> tight constraints on Modified gravity parameters through a Euclid-like survey

 

  • We can engineer summary statistics that extract more information by exploiting environmental dependencies. But, can we model them to the same accuracy?

 

What is the impact of baryons on small scales?

Are there degeneracies with other cosmological parameters that would alter our constraints?

Simulation-based clustering predictions to constrain Modified Gravity theories

By carol cuesta

Simulation-based clustering predictions to constrain Modified Gravity theories

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