Intrinsic alignments of dark matter halos in $f(R)$ gravity simulations
  There is a growing interest of utilizing intrinsic alignment (IA) of galaxy
shapes as a geometric and dynamical probe of cosmology. In this paper we
present the first measurements of IA in a modified gravity model using the
gravitational shear-intrinsic ellipticity correlation (GI) and intrinsic
ellipticity-ellipticity correlation (II) functions of dark-matter halos from
$f(R)$ gravity simulations. By comparing them with the same statistics measured
in $\Lambda$CDM simulations, we find that the IA statistics in different
gravity models show distinguishable features, with a trend similar to the case
of conventional galaxy clustering statistics. Thus, the GI and II correlations
are found to be useful in distinguishing between the $\Lambda$CDM and $f(R)$
gravity models. More quantitatively, IA statistics enhance detectability of the
imprint of f(R) gravity on large scale structures by $\sim20\%$ when combined
with the conventional halo clustering in redshift space. Our results
demonstrate the usefulness of IA statistics as a probe of gravity beyond a
consistency test of $\Lambda$CDM and general relativity.
