Enormous extragalactic void is pushing on the Milky Way

The Milky Way galaxy is currently racing through space at about 2 million km/h (1.2 million mph), on a journey towards a gravitational anomaly known as the Great Attractor, which is in turn being dragged towards an even bigger structure, the Shapley Supercluster. But there’s more to the story than these mysterious monsters: Astronomers have now discovered a huge extragalactic void, called the Dipole Repeller, that’s pushing us away.

More…

Voids can’t push…

dv said:

Voids can’t push…

They can if the explosion that created them is powerful enough.

“The Shapley Supercluster, some 650 million light-years away, is dense with mass and is constantly drawing more mass into it, including the entire Laniakea Supercluster of galaxies that contains the Milky Way.”

True.

“Since it’s difficult to observe an absence of galaxies, a team of researchers from the Hebrew University of Jerusalem, along with scientists in the US and France, created a 3D map of the “galaxy flow field” – essentially, tracking the paths that galaxies are taking on their journey through the universe. Building this map using data from telescopes like Hubble, the team focused on galaxies with peculiar velocities, which means they’re moving faster than the universe is expanding. Through statistical analysis of several different datasets, the team was able to infer the underlying distribution of mass throughout the universe.”

They can do that?! That’s not easy to do even in theory, because almost all of the data is missing. Redshift is known of course, but how can they distinguish cosmological redshift from anomalous redshift, and further the lateral motion of galaxies parallel to the line of sight is completely unknown.