High-resolution VLBI observations of and modelling the radio emission from the TDE AT2019dsg. (arXiv:2106.15799v2 [astro-ph.HE] UPDATED)
<a href="http://arxiv.org/find/astro-ph/1/au:+Mohan_P/0/1/0/all/0/1">Prashanth Mohan</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+An_T/0/1/0/all/0/1">Tao An</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Zhang_Y/0/1/0/all/0/1">Yingkang Zhang</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Yang_J/0/1/0/all/0/1">Jun Yang</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Yang_X/0/1/0/all/0/1">Xiaolong Yang</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Wang_A/0/1/0/all/0/1">Ailing Wang</a>
A tidal disruption event (TDE) involves the shredding of a star in the
proximity of a supermassive black hole (SMBH). The nearby ($approx$230 Mpc)
relatively radio-quiet, thermal emission dominated source AT2019dsg is the
first TDE with a potential neutrino association. The origin of non-thermal
emission remains inconclusive; possibilities include a relativistic jet or a
sub-relativistic 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 $pm$ 0.65 mas yr$^{-1}$ ($3.2 pm
2.2~c$; $1-sigma$). Modelling the radio emission favors an origin from the
interaction between a decelerating outflow (velocity $approx$ 0.1 $c$) and a
dense circum-nuclear medium. The transition of the synchrotron self-absorption
frequency through the observation band marks a peak flux density of 1.19 $pm$
0.18 mJy at 152.8 $pm$ 16.2 days. An equipartition analysis indicates an
emission region distance of $geqslant$ 4.7 $times$ 10$^{16}$ cm, magnetic
field strength $geqslant$ 0.17 G, and number density $geqslant$ 5.7 $times$
10$^{3}$ cm$^{-3}$. The disruption involves a $approx$ 2 $M_odot$ star with a
penetration factor $approx 1$ and a total energy output of $leqslant$ 1.5
$times$ 10$^{52}$ erg. The outflow is radiatively driven by accretion of
stellar debris onto the SMBH. Neutrino production is likely related to the
acceleration of protons to PeV energies and the availability of a suitable
cross-section at the outflow base. The present study thus helps exclude
jet-related origins for non-thermal emission and neutrino production, and
constrains non-jetted scenarios.
A tidal disruption event (TDE) involves the shredding of a star in the
proximity of a supermassive black hole (SMBH). The nearby ($approx$230 Mpc)
relatively radio-quiet, thermal emission dominated source AT2019dsg is the
first TDE with a potential neutrino association. The origin of non-thermal
emission remains inconclusive; possibilities include a relativistic jet or a
sub-relativistic 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 $pm$ 0.65 mas yr$^{-1}$ ($3.2 pm
2.2~c$; $1-sigma$). Modelling the radio emission favors an origin from the
interaction between a decelerating outflow (velocity $approx$ 0.1 $c$) and a
dense circum-nuclear medium. The transition of the synchrotron self-absorption
frequency through the observation band marks a peak flux density of 1.19 $pm$
0.18 mJy at 152.8 $pm$ 16.2 days. An equipartition analysis indicates an
emission region distance of $geqslant$ 4.7 $times$ 10$^{16}$ cm, magnetic
field strength $geqslant$ 0.17 G, and number density $geqslant$ 5.7 $times$
10$^{3}$ cm$^{-3}$. The disruption involves a $approx$ 2 $M_odot$ star with a
penetration factor $approx 1$ and a total energy output of $leqslant$ 1.5
$times$ 10$^{52}$ erg. The outflow is radiatively driven by accretion of
stellar debris onto the SMBH. Neutrino production is likely related to the
acceleration of protons to PeV energies and the availability of a suitable
cross-section at the outflow base. The present study thus helps exclude
jet-related origins for non-thermal emission and neutrino production, and
constrains non-jetted scenarios.
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