Are most detected tidal disruption events partial?

arXiv:2606.22919 · astro-ph.HE · Submitted 2026-06-22 · Read on arXiv

Megha Sharma, Daniel J. Price, Alexander Heger, Katie Auchettle

Monash University · Monash University, Univ. Grenoble Alpes · Monash University · University of Melbourne, University of California, Santa Cruz

astro-ph.HE

Submitted: 2026-06-22

Comments: 19 pages, 15 Figures, accepted to ApJ

Code: https://github.com/danieljprice/phantom

License: http://creativecommons.org/licenses/by/4.0/

The gist: During a tidal disruption event (TDE), a star loses mass due to the tidal gravitational forces of the black hole.

Terminology

Abstract

During a tidal disruption event (TDE), a star loses mass due to the tidal gravitational forces of the black hole. In a partial tidal disruption event, a stellar remnant is left behind. Several dozen TDEs have been detected so far, including repeating partial events. We use the Phantom smoothed particle hydrodynamics code to model the disruption of a 1 Msun star around a 10 6 Msun black hole for impact parameters resulting in less than equal to 50 % mass loss. We only consider zero energy orbits. Our simulations show that the mass fallback rate can exceed the Eddington limit for beta greater than or equal to 0.8, allowing debris to obscure the accretion disc by forming a reprocessing layer, similar to full TDEs. The mass fallback rate is shallower than t-5/3, tracking closer to t-9/4. Assuming thermal emission from the debris, that shock heating is trapped, that electron scattering dominates the opacity, and a color correction f col of 1.7, we find temperatures of 10 4 K, optical bolometric luminosities of 10 42-44 erg/s and blackbody radii ranging from 10-100 au for our simulations. We compare our values with observations and find support for the previous argument that some TDEs classified as full disruptions might actually be partial. Moreover, our results explain the detected optical/UV TDEs. We also find that our zero energy partial TDEs have properties similar to the repeating partial TDEs such as ASSASN-19dj, ASSASN-14ko, ASSASN-18ul, ASSASN-22ci, AT2020vdq and AT2022dbl. In the beta=0.8, isentropic simulation where radiation is assumed to escape, we find X-ray luminosities of 10 44-45 erg/s and radii lower than the inner most stable circular orbit.

Sources

Related papers