Chameleon $f(R)$ gravity on the Virgo cluster scale
Abstract
Models of modified gravity offer promising alternatives to the concordance $\Lambda$CDM cosmology to explain the latetime acceleration of the universe. A popular such model is $f(R)$ gravity, in which the Ricci scalar in the EinsteinHilbert action is replaced by a general function of it. We study the $f(R)$ model of Hu & Sawicki (2007), which recovers standard General Relativity in high density regimes, while reproducing the desired latetime acceleration at cosmological scales. We run a suite of high resolution zoom simulations using the ECOSMOG code to examine the effect of $f(R)$ gravity on the properties of a halo that is analogous to the Virgo cluster. We show that the velocity dispersion profiles can potentially discriminate between $f(R)$ models and $\Lambda$CDM, and provide complementary analysis of lensing signal profiles to explore the possibility to further distinguish the different $f(R)$ models. Our results confirm the techniques explored by Cabre et al. (2012) to quantify the effect of environment in the behavior of $f(R)$ gravity, and we extend them to study halo satellites at various redshifts. We find that the modified gravity effects in our models are most observable at low redshifts, and that effects are generally stronger for satellites far from the center of the main halo. We show that the screening properties of halo satellites trace very well that of dark matter particles, which means that lowresolution simulations in which subhalos are not very well resolved can in principle be used to study satellite properties. We discuss observables, particularly for halo satellites, that can potentially be used to constrain the observational viability of $f(R)$ gravity.
 Publication:

arXiv eprints
 Pub Date:
 August 2014
 arXiv:
 arXiv:1408.2856
 Bibcode:
 2014arXiv1408.2856C
 Keywords:

 Astrophysics  Cosmology and Nongalactic Astrophysics
 EPrint:
 24 pages, 17 figures, submitted to MNRAS