Constraints on $f(R)$ and nDGP Modified Gravity Model Parameters with Cluster Abundances and Galaxy Clustering. (arXiv:2101.08728v1 [astro-ph.CO])

<a href="http://arxiv.org/find/astro-ph/1/au:+Liu_R/0/1/0/all/0/1">Rayne Liu</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Valogiannis_G/0/1/0/all/0/1">Georgios Valogiannis</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Battaglia_N/0/1/0/all/0/1">Nicholas Battaglia</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Bean_R/0/1/0/all/0/1">Rachel Bean</a>

We present forecasted cosmological constraints from combined measurements of

galaxy cluster abundances from the Simons Observatory and galaxy clustering

from a DESI-like experiment on two well-studied modified gravity models, the

chameleon-screened $f(R)$ Hu-Sawicki model and the nDGP braneworld Vainshtein

model.

A Fisher analysis is conducted using $sigma_8$ constraints derived from

thermal Sunyaev-Zel’dovich (tSZ) selected galaxy clusters, as well as linear

and mildly non-linear redshift-space 2-point galaxy correlation functions. We

find that the cluster abundances drive the constraints on the nDGP model while

$f(R)$ constraints are led by galaxy clustering. The two tracers of the

cosmological gravitational field are found to be complementary, and their

combination significantly improves constraints on the $f(R)$ in particular in

comparison to each individual tracer alone.

For a fiducial model of $f(R)$ with $text{log}_{10}(f_{R0})=-6$ and $n=1$ we

find combined constraints of $sigma(text{log}_{10}(f_{R0}))=0.48$ and

$sigma(n)=2.3$, while for the nDGP model with $n_{text{nDGP}}=1$ we find

$sigma(n_{text{nDGP}})=0.087$. Around a fiducial General Relativity (GR)

model, we find a $95%$ confidence upper limit on $f(R)$ of

$f_{R0}leq5.68times 10^{-7}$. Our results present the exciting potential to

utilize upcoming galaxy and CMB survey data available in the near future to

discern and/or constrain cosmic deviations from GR.

We present forecasted cosmological constraints from combined measurements of

galaxy cluster abundances from the Simons Observatory and galaxy clustering

from a DESI-like experiment on two well-studied modified gravity models, the

chameleon-screened $f(R)$ Hu-Sawicki model and the nDGP braneworld Vainshtein

model.

A Fisher analysis is conducted using $sigma_8$ constraints derived from

thermal Sunyaev-Zel’dovich (tSZ) selected galaxy clusters, as well as linear

and mildly non-linear redshift-space 2-point galaxy correlation functions. We

find that the cluster abundances drive the constraints on the nDGP model while

$f(R)$ constraints are led by galaxy clustering. The two tracers of the

cosmological gravitational field are found to be complementary, and their

combination significantly improves constraints on the $f(R)$ in particular in

comparison to each individual tracer alone.

For a fiducial model of $f(R)$ with $text{log}_{10}(f_{R0})=-6$ and $n=1$ we

find combined constraints of $sigma(text{log}_{10}(f_{R0}))=0.48$ and

$sigma(n)=2.3$, while for the nDGP model with $n_{text{nDGP}}=1$ we find

$sigma(n_{text{nDGP}})=0.087$. Around a fiducial General Relativity (GR)

model, we find a $95%$ confidence upper limit on $f(R)$ of

$f_{R0}leq5.68times 10^{-7}$. Our results present the exciting potential to

utilize upcoming galaxy and CMB survey data available in the near future to

discern and/or constrain cosmic deviations from GR.

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