Measuring Stellar and Black Hole Masses of Tidal Disruption Events

The flare produced when a star is tidally disrupted by a supermassive black hole holds potential as a diagnostic of both the black hole mass and the star mass. We propose a new method to realize this potential based upon a physical model of optical/UV light production in which shocks near the apocenters of debris orbits dissipate orbital energy, which is then radiated from that region. Measurement of the optical/UV luminosity and color temperature at the peak of the flare leads directly to the two masses. The black hole mass depends mostly on the temperature observed at peak luminosity, while the mass of the disrupted star depends mostly on the peak luminosity. We introduce TDEmass, a method to infer the black hole and stellar masses given these two input quantities. Using TDEmass, we find, for 21 well-measured events, black hole masses between 5 × 10⁵ and 10⁷ M _⊙ and disrupted stars with initial masses between 0.6 and 13 M _⊙. An open-source python-based tool for TDEmass is available at https://github.com/taehoryu/TDEmass.git.