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Title: The Peak of the Fallback Rate from Tidal Disruption Events: Dependence on Stellar Type

A star completely destroyed in a tidal disruption event (TDE) ignites a luminous flare that is powered by the fallback of tidally stripped debris to a supermassive black hole (SMBH) of massM. We analyze two estimates for the peak fallback rate in a TDE, one being the “frozen-in” model, which predicts a strong dependence of the time to peak fallback rate,tpeak, on both stellar mass and age, with 15 days ≲tpeak≲ 10 yr for main sequence stars with masses 0.2 ≤M/M≤ 5 andM= 106M. The second estimate, which postulates that the star is completely destroyed when tides dominate the maximum stellar self-gravity, predicts thattpeakis very weakly dependent on stellar type, withtpeak=23.2±4.0daysM/106M1/2for 0.2 ≤M/M≤ 5, whiletpeak=29.8±3.6daysM/106M1/2for a Kroupa initial mass function truncated at 1.5M. This second estimate also agrees closely with hydrodynamical simulations, while the frozen-in model is discrepant by orders of magnitude. We conclude that (1) the time to peak luminosity in complete TDEs is almost exclusively determined by SMBH mass, and (2) massive-star TDEs power the largest accretion luminosities. Consequently, (a) decades-long extra-galactic outbursts cannot be powered by complete TDEs, including massive-star disruptions, and (b) the most highly super-Eddington TDEs are powered by the complete disruption of massive stars, which—if responsible for producing jetted TDEs—would explain the rarity of jetted TDEs and their preference for young and star-forming host galaxies.

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Author(s) / Creator(s):
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DOI PREFIX: 10.3847
Date Published:
Journal Name:
The Astrophysical Journal Letters
Medium: X Size: Article No. L2
["Article No. L2"]
Sponsoring Org:
National Science Foundation
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