Modified Gravity Spins Up Galactic Halos
  We investigate the effect of modified gravity on the specific angular
momentum of galactic halos by analyzing the halo catalogs at z=0 from
high-resolution N-body simulations for a f(R) gravity model that meets the
solar-system constraint. It is shown that the galactic halos in the f(R)
gravity model tend to acquire significantly higher specific angular momentum
than those in the standard LCDM model. The largest difference in the specific
angular momentum distribution between these two models occurs for the case of
the isolated galactic halos with mass less than 10^{11}M_sun/h, which are
likely least shielded by the chameleon screening mechanism. As the specific
angular momentum of galactic halos is rather insensitive to the other
cosmological parameters, it can in principle be an independent discriminator of
modified gravity. We speculate a possibility of using the relative abundance of
the low surface brightness galaxies (LSBGs) as a test of GR given that the
formation of the LSBGs befalls in the fast spinning dark halos.
