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First light from tidal disruption events

Bonnerot, Clément and Lu, Wenbin and Hopkins, Philip F. (2021) First light from tidal disruption events. Monthly Notices of the Royal Astronomical Society, 504 (4). pp. 4885-4905. ISSN 0035-8711. doi:10.1093/mnras/stab398.

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When a star comes too close to a supermassive black hole, it gets torn apart by strong tidal forces in a tidal disruption event, or TDE. Half of the elongated stream of debris comes back to the stellar pericentre where relativistic apsidal precession induces a self-crossing shock. As a result, the gas gets launched into an outflow that can experience additional interactions, leading to the formation of an accretion disc. We carry out the first radiation–hydrodynamics simulations of this process, making use of the same injection procedure to treat the self-crossing shock as in our previous adiabatic study. Two sets of realistic parameters of the problem are considered that correspond to different strengths of this initial interaction. In both cases, we find that the injected matter has its trajectories promptly circularized by secondary shocks taking place near the black hole. However, the generated internal energy efficiently diffuses away in the form of radiation, which results in a thin vertical profile of the formed disc. The diffusing photons promptly irradiate the surrounding debris until they emerge with a bolometric luminosity of L ≈ 10⁴⁴ erg s⁻¹. Towards the self-crossing shock, diffusion is, however, slowed that results in a shallower luminosity increase, with a potentially significant component in the optical band. Matter launched to large distances continuously gains energy through radiation pressure, which can cause a significant fraction to become unbound. This work provides direct insight into the origin of the early emission from TDEs, which is accessed by a rapidly increasing number of observations.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper ItemMovies of the simulation ItemGIZMO code
Bonnerot, Clément0000-0001-9970-2843
Lu, Wenbin0000-0002-1568-7461
Hopkins, Philip F.0000-0003-3729-1684
Additional Information:© 2021 The Author(s). Published by Oxford University Press on behalf of Royal Astronomical Society. Accepted 2021 January 27. Received 2021 January 18; in original form 2020 December 22. Published: 11 February 2021. We thank Tony Piro, Eliot Quataert, Sterl Phinney, Daniel Kasen, and Nathan Roth for useful discussions. We acknowledge the use of SPLASH (Price 2007) for producing most of the figures in this paper. This research benefited from interactions at the ZTF Theory Network Meeting, partly funded by the National Science Foundation under grant no. NSF PHY-1748958. The research of CB was funded by the Gordon and Betty Moore Foundation through grant GBMF5076. WL was supported by the David and Ellen Lee Fellowship at Caltech. Data Availability: The data underlying this article will be shared on reasonable request to the corresponding author. A public version of the GIZMO code is available at
Group:Astronomy Department, TAPIR
Funding AgencyGrant Number
Gordon and Betty Moore FoundationGBMF5076
David and Ellen Lee Postdoctoral ScholarshipUNSPECIFIED
Subject Keywords:black hole physics – hydrodynamics – galaxies: nuclei
Issue or Number:4
Record Number:CaltechAUTHORS:20210302-122414919
Persistent URL:
Official Citation:Clément Bonnerot, Wenbin Lu, Philip F Hopkins, First light from tidal disruption events, Monthly Notices of the Royal Astronomical Society, Volume 504, Issue 4, July 2021, Pages 4885–4905,
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:108271
Deposited By: Tony Diaz
Deposited On:02 Mar 2021 21:11
Last Modified:24 May 2021 18:07

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