Tycho's Remnant: Post-Shock Temperature, Compression and the Cosmic-Ray Energy Share

This paper computes the energy, density and acceleration budgets of Tycho's remnant from a small set of adopted, published input values, using the relations stated in the Methods and a deposited script that reproduces every number. For the unmodified strong shock, a speed of 4.5e+03 km/s implies a post-shock temperature of 24.2 keV; assigning fifteen percent of the shock energy to cosmic rays raises the compression ratio to 4.9 and lowers the expected temperature to 18 keV. The lowered temperature is the direction, and roughly the size, of the discrepancy that X-ray measurements of Tycho's shocked interstellar gas have reported for two decades, which is why this remnant remains a standard exhibit in the case for efficient acceleration. 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.