Classifying self-gravitating radiations

Understand

We study a static system of self-gravitating radiations confined in a sphere by using numerical and analytical calculations.

• Due to the scaling symmetry of radiations, most of main properties of a solution can be represented as a segment of a solution curve on a plane of two-dimensional scale invariant variables.
• We define an `approximate horizon' (AH) from the analogy with an apparent horizon.
• Any solution curve contains a unique point which corresponds to the AH.