Peculiar Velocity Anomaly from Forces Beyond Gravity?
  We address recently reported anomalously large bulk flows on scales of 100
Mpc/h and beyond. These coherent motions of galaxies challenge the standard
LCDM concordance model as well as a large class of competitive models of dark
energy and modified gravity. If confirmed, they may support alternative models
that include extra couplings inducing enhanced peculiar velocities on large
scales. A complementary probe of the evolution of large-scale perturbations is
the integrated Sachs-Wolfe effect; we explore the connection between this
observable and the bulk flow. For illustration, we consider a coupling between
dark energy and dark matter as well as a specific cosmological model, growing
neutrino quintessence.
