Mon. Not. R. Astron. Soc., 507, 3207-3227 (2021/November-1)
Global simulations of tidal disruption event disc formation via stream injection in GRRMHD.
Abstract (from CDS):
We use the general relativistic radiation magnetohydrodynamics code KORAL to simulate the accretion disc formation resulting from the tidal disruption of a solar mass star around a supermassive black hole (BH) of mass 106 M☉. We simulate the disruption of artificially more bound stars with orbital eccentricity e <= 0.99 (compared to the more realistic case of parabolic orbits with e = 1) on close orbits with impact parameter β >= 3. We use a novel method of injecting the tidal stream into the domain, and we begin the stream injection at the peak fallback rate in this study. For two simulations, we choose e = 0.99 and inject mass at a rate that is similar to parabolic TDEs. We find that the disc only becomes mildly circularized with eccentricity e ≃ 0.6 within the 3.5 d that we simulate. The rate of circularization is faster for pericenter radii that come closer to the BH. The emitted radiation is mildly super-Eddington with L_ bol_~3-5 L_ Edd_ and the photosphere is highly asymmetric with the photosphere being significantly closer to the inner accretion disc for viewing angles near pericenter. We find that soft X-ray radiation with Trad ≃ 3-5 x 105 K may be visible for chance viewing angles. Our simulations suggest that TDEs should be radiatively inefficient with η ≃ 0.009-0.014.