The Crab Nebula's Expansion Energy: Partition Between Motion, Field and Radiation

This paper computes the energy, density and acceleration budgets of the Crab Nebula from a small set of adopted, published input values, using the relations stated in the Methods and a deposited script that reproduces every number. At the adopted mass and filament speed, the expansion energy is 3.61e+49 erg, a fraction 0.436 of the rotational energy surrendered since an adopted birth period of 14 milliseconds, so a share of the same order remains for radiation and for the stored particle population. The radiated output integrated over the age is of the same order as the injected total of 8.27e+49 erg, which is the quantitative content of the statement that the Crab converts spin-down power to light with an efficiency approached by no other known nebula; the instantaneous X-ray efficiency alone is 0.109. The calculation is a computation from stated assumptions, not a measurement, and each headline result is reported together with the diagnostic that tests whether the assumed evolutionary phase applies to this object.