Is the 'great attractor' a loop of cosmic string?

Abstract

Recent measurements of galaxy velocities suggest that the observed large-scale streaming^1,2 may be attributed to a massive (M ≃ 10¹⁶ M⊙) 'attractor' located at a distance D ≃45 h⁻¹ Mpc (ref. 3; h = Hubble's constant in units of 100 km s⁻¹ Mpc⁻¹). We explore the idea that the streaming was induced by a large, moving loop of cosmic string. A stationary loop induces a velocity field that falls off as r⁻¹ where r is the distance from the loop. This is somewhat modified by the motion of the loop, but the r⁻¹ profile still persists in much of the wake of the string. The standard gaussian δ-field (density perturbation) inflationary models of cold or hot dark matter predict, on the other hand, a velocity that should fall off as r⁻³ away from the density peak. Extension of this model to the Local Supercluster (LSC) allows one to understand its Virgocentric velocity field of r⁻¹.