Fundamental plane

Niels Bohr Institutet
17. december 2020
The orange ellipses represent galaxies. The farther they are to the right, the larger they are, according to the observations. Being higher up can mean they the are either more massive, or that they are fainter. Or both.

The galaxies fall in two groups — the ones in the bottom are observed properties of the distant galaxies, seen 10 billions years ago, while the upper group represent local galaxies, seen roughly like they are today.

In both cases, the galaxies are seen to fall in a rather narrow range — this is in fact the Fundamental Plane "seen from the side", so to speak (if this makes little sense, try viewing the 3D version).