High-resolution VLBI observations of and modelling the radio emission from the TDE AT2019dsg

2021/06/30 by Prashanth Mohan, P. Mohan, Tao An +4 · 16 citations
Physics and Astronomy · #Accretion (finance) #Astronomy #Astrophysics #Astrophysics and Cosmic Phenomena #Equipartition theorem #Flare #Galaxy #Gamma-ray bursts and supernovae #Magnetic field #Neutrino #Nuclear physics #Outflow #Physics #Radio Astronomy Observations and Technology #Supermassive black hole #Very-long-baseline interferometry #astro-ph.HE

paper · pdf · open access · doi:10.3847/1538-4357/ac4cb2

published in The Astrophysical Journal 927(1), 74 (IOP Publishing) · 17 pages, 2 figures, 4 tables. Accepted for publication in The Astrophysical Journal

arxiv created 2022/01/17 · openalex publication_date 2022/03/01 · arxiv updated 2022/03/14 · openalex created_date 2022/04/03 · openalex updated_date 2026/08/05

Abstract

A tidal disruption event (TDE) involves the shredding of a star in the proximity of a supermassive black hole (SMBH). The nearby (≈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 ± 0.65 mas yr^-1 (3.2 ± 2.2~c; 1-σ). Modelling the radio emission favors an origin from the interaction between a decelerating outflow (velocity ≈ 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 ± 0.18 mJy at 152.8 ± 16.2 days. An equipartition analysis indicates an emission region distance of \geqslant 4.7 × 10¹⁶ cm, magnetic field strength \geqslant 0.17 G, and number density \geqslant 5.7 × 10³ cm^-3. The disruption involves a ≈ 2 M_\odot star with a penetration factor ≈ 1 and a total energy output of \leqslant 1.5 × 10⁵² 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.

Citations

• Fluid dynamics of relativistic blast waves
• RADIO MONITORING OF THE TIDAL DISRUPTION EVENT SWIFT J164449.3+573451. I. JET ENERGETICS AND THE PRISTINE PARSEC-SCALE ENVIRONMENT OF A SUPERMASSIVE BLACK HOLE
• Radio Monitoring of the Tidal Disruption Event Swift J164449.3+573451. III. Late-time Jet Energetics and a Deviation from Equipartition
• Seventeen Tidal Disruption Events from the First Half of ZTF Survey Observations: Entering a New Era of Population Studies
• High-energy Neutrino and Gamma-Ray Emission from Tidal Disruption Events
• Neutrino emission from an off-axis jet driven by the tidal disruption event AT2019dsg
• A tidal disruption event coincident with a high-energy neutrino