The TDE Population from First-Principles Models of Stellar Disruption and Debris Dynamics

We present a physically-grounded population model for optical tidal disruption events (TDEs) that combines first-principles hydrodynamic simulations of stellar disruption with statistical inference of the underlying stellar and black hole populations. The model’s prediction of peak luminosity is based directly on recent global simulations that follow the disruption self-consistently and contains no tunable parameters related to the emission physics. We construct the predicted joint distribution of peak luminosity and black hole mass, including both full and partial disruptions, and compare it to a sample of observed TDEs using Bayesian inference and Markov chain Monte Carlo sampling. We find that the model reproduces the distribution in the ($M_{BH},L_{peak}$) plane for the bulk of the observed TDE population with good statistical consistency. The data strongly favor an old stellar population, with a sharp suppression of stars above $M_* \simeq 1.5 - 2 M_\odot$. They also indicate that, at fixed stellar mass, the volumetric TDE rate is nearly independent of black hole mass. Partial disruptions contribute a substantial fraction ($\sim 30%$) of detected events in flux-limited samples and are essential for reproducing the observed distribution. The inferred population properties are robust to different approximations to the stellar mass-radius relation, although the event rate at high luminosity is sensitive to the form of this relation for massive stars. We predict a large population of difficult to detect low luminosity TDEs, implying that the true volumetric TDE rate may exceed that inferred from present samples by up to an order of magnitude.

💡 Research Summary

This paper presents a physically‑grounded population model for optical tidal disruption events (TDEs) that directly links the peak luminosity of a flare to the fundamental hydrodynamics of stellar disruption. The authors combine results from three independent, state‑of‑the‑art global three‑dimensional simulations of full and partial stellar disruptions with a Bayesian statistical framework to predict the joint distribution of peak luminosity (L peak) and supermassive black‑hole mass (M BH). The key innovation is that the L peak–M BH relation is derived from first‑principles simulations, requiring no tunable emission‑physics parameters.

The theoretical foundation starts from the classic tidal radius (r_t\sim R_(M_{\rm BH}/M_)^{1/3}) and introduces two correction factors, (\Psi(M_,M_{\rm BH})) for the effective disruption radius and (\Xi(M_,M_{\rm BH})) for the spread in specific orbital energy of the debris. Both factors are of order unity but encode the dependence on the stellar internal density profile and relativistic effects. For a given pericenter distance (r_p), the fraction of stellar mass stripped is (\Delta M/M_* \approx (r_p/R_T)^{-3}), which drops sharply for partial disruptions.

Using the simulation‑calibrated energy dissipation rate in the stream–stream and nozzle shocks, the authors derive an analytic expression for the peak bolometric luminosity:

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