Soft X-Ray Emission Measure, Luminosity and Cooling Time of the Local Bubble Interior

The hot gas filling the Local Bubble radiates in soft X-rays, and its emission measure, luminosity and cooling time follow from the density and temperature that X-ray spectroscopy returns. For a spherical volume of radius 100 parsecs at the published interior density, the emission measure is 2.77e+57 per cubic centimetre, the radiated luminosity is 2.77e+35 erg per second, and the ratio of stored thermal energy to luminosity gives a cooling time of 2.77e+07 years. That cooling time exceeds the age usually assigned to the bubble's current hot phase, which means the interior we observe has not had time to cool radiatively since it was last reheated, consistent with supernova reheating within the last few million years. The quantities are computed from stated published inputs with the deposited script, not measured anew.