The tidal disruption of stars by supermassive black holes (SMBHs) can be used to probe the SMBH mass function, the properties of individual stars, and stellar dynamics in galactic nuclei. Upcoming missions will detect thousands of TDEs, and accurate theoretical modeling is required to interpret the data with precision. Here we analyze the influence of more realistic stellar structure on the outcome of TDEs; in particular, we compare the fallback rates -being the rate at which tidally-disrupted debris returns to the black hole -from progenitors generated with the stellar evolution code mesa to γ ≃ 4/3 and γ = 5/3 polytropes. We find that mesa-generated density profiles yield qualitatively-different fallback rates as compared to polytropic approximations, and that only the fallback curves from lowmass (1M ⊙ or less), zero-age main-sequence stars are well fit by either a γ ≃ 4/3 or 5/3 polytrope. Stellar age has a strong affect on the shape of the fallback curve, and can produce characteristic timescales (e.g., the time to the peak of the fallback rate) that greatly differ from the polytropic values. We use these differences to assess the degree to which the inferred black hole mass from the observed lightcurve can deviate from the true value, and find that the discrepancy can be at the order of magnitude level. Accurate stellar structure also leads to a substantial variation in the critical impact parameter at which the star is fully disrupted, and can increase the susceptibility of the debris stream to fragmentation under its own self-gravity. These results suggest that detailed modeling is required to accurately interpret observed lightcurves of TDEs.

The tidal force from a supermassive black hole can rip apart a star that passes close enough in what is known as a Tidal Disruption Event. Typically half of the destroyed star remains bound to the black hole and falls back on highly eccentric orbits, forming an accretion flow which powers a luminous flare. In this paper we use analytical and numerical calculations to explore the effect of stellar rotation on the fallback rate of material. We find that slowly spinning stars (Ω * 0.01Ω breakup ) provide only a small perturbation to fallback rates found in the non-spinning case. However when the star spins faster, there can be significant effects. If the star is spinning retrograde with respect to its orbit the tidal force from the black hole has to spin down the star first before disrupting it, causing delayed and sometimes only partial disruption events. However, if the star is spinning prograde this works with the tidal force and the material falls back sooner and with a higher peak rate. We examine the power-law index of the fallback curves, finding that in all cases the fallback rate overshoots the canonical t −5/3 rate briefly after the peak, with the depth of the overshoot dependent on the stellar spin. We also find that in general the late time evolution is slightly flatter than the canonical t −5/3 rate. We therefore conclude that considering the spin of the star may be important in modelling observed TDE lightcurves.