Peculiar Velocity Anomaly from Forces Beyond Gravity?

Understand

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.