András Kovács - The Dipole Repeller

Wednesday 1 Mar 2017, 13:00 → 14:00 Europe/Madrid

Seminar (IFAE)

Jelena Aleksic (IFAE), Joern Lange (IFAE Barcelona), John E Ward (IFAE)

For nearly a century, we’ve known that our Universe is expanding, and that the distance to a galaxy determines its average apparent recessional speed from us. But on top of that is an additional motion - a peculiar velocity - caused by the local gravitational field of the Universe. When we look at the motion of our own galaxy, we see it’s moving about twice as fast in one direction as the attractive masses would allow. The “Great Attractor” as a source of our motion represents a longstanding puzzle in cosmography. Underdense regions, however, where there’s less mass and gravity than average, can serve as an effective repeller, failing to attract other matter just as much as overdense regions can attract it. Thanks to a newly mapped cosmic void, we might finally understand how our galaxy is moving through the Universe. In this talk, I will introduce the so-called “Dipole Repeller” and discuss implications for cosmological inference at large scales.