High-resolution VLBI Observations of and Modeling the Radio Emission from the Tidal Disruption Event AT2019dsg
Artikel i vetenskaplig tidskrift, 2022

A tidal disruption event (TDE) involves the shredding of a star in the proximity of a supermassive black hole (SMBH). The nearby (approximate to 230 Mpc) relatively radio-quiet, thermal-emission-dominated source AT2019dsg is the first TDE with a potential neutrino association. The origin of nonthermal emission remains inconclusive; possibilities include a relativistic jet or a subrelativistic outflow. Distinguishing between them can address neutrino production mechanisms. High-resolution very long baseline interferometry 5 GHz observations provide a proper motion of 0.94 +/- 0.65 mas yr(-1) (3.2 +/- 2.2 c; 1 sigma). Modeling the radio emission favors an origin from the interaction between a decelerating outflow (velocity approximate to 0.1 c) and a dense circumnuclear medium. The transition of the synchrotron self-absorption frequency through the observation band marks a peak flux density of 1.19 +/- 0.18 mJy at 152.8 +/- 16.2 days. An equipartition analysis indicates an emission-region distance of >= 4.7 x 10(16) cm, magnetic field strength >= 0.17 G, and number density >= 5.7 x 10(3) cm(-3). The disruption involves a approximate to 2 M (circle dot) star with a penetration factor approximate to 1 and a total energy output of <= 1.5 x 10(52) erg. The outflow is radiatively driven by the accretion of stellar debris onto the SMBH. Neutrino production is likely related to the acceleration of protons to peta-electron-volt energies and the availability of a suitable cross section at the outflow base. The present study thus helps exclude jet-related origins for nonthermal emission and neutrino production, and constrains nonjetted scenarios.


Prashanth Mohan

Chinese Academy of Sciences

Tao An

Chinese Academy of Sciences

Yingkang Zhang

Chinese Academy of Sciences

Jun Yang

Chalmers, Rymd-, geo- och miljövetenskap, Onsala rymdobservatorium, Observationssupport

Xiaolong Yang

Chinese Academy of Sciences

Ailing Wang

Chinese Academy of Sciences

Astrophysical Journal

0004-637X (ISSN) 1538-4357 (eISSN)

Vol. 927 1 74


Subatomär fysik

Astronomi, astrofysik och kosmologi

Fusion, plasma och rymdfysik



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