Ayumu Terukina, Kazuhiro Yamamoto
We investigate the gas density, temperature and pressure profiles in a dark matter halo under the influence of the chameleon modified gravity. Utilizing an analytic approximate solution for the chameleon field equation with the source term with the Navarro-Frenk-White universal density profile, we solve the hydrostatic equilibrium equation for the gas coupled with the scalar field. We find that the gas distribution becomes compact because larger pressure gradient is necessary due to the additional chameleon force. The characteristic radius of the gas distribution is determined by the configuration of the chameleon field. For a smaller mass halo, the gas distribution could be much smaller than the virial radius, which put a constraint on the chameleon field configuration. We also discuss about an application of our results to an f(R) modified gravity model, which may put a tight constraint on the model parameter of |f_{R0}|\simlt 10^{-5}.
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http://arxiv.org/abs/1203.6163
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