Orateur
Description
We look for signatures of the Hu-Sawicki f (R) modified gravity theory, proposed to explain the observed accelerated expansion of the
universe; in observations of the galaxy distribution, the cosmic microwave background (CMB), and gravitational lensing of the CMB.
We study constraints obtained by using observations of only the CMB primary anisotropies, before adding the galaxy power spectrum
and its cross-correlation with CMB lensing. We show that cross-correlation of the galaxy distribution with lensing measurements is
crucial to breaking parameter degeneracies, placing tighter constraints on the model. In particular, we set a strong upper limit on
log| fR0 |< −4.61 at 95% confidence level. This means that while the model may explain the accelerated expansion, its impact on large-
scale structure closely resembles General Relativity. Studies of this kind with future data sets will probe smaller potential deviations
from General Relativity.
