The radio detection and accretion properties of the peculiar nuclear transient AT 2019avd
Artikel i vetenskaplig tidskrift, 2023

AT 2019avd is a nuclear transient detected from infrared to soft X-rays, though its nature is yet unclear. The source has shown two consecutive flaring episodes in the optical and the infrared bands, and its second flare was covered by X-ray monitoring programs. During this flare, the UVOT/Swift photometries revealed two plateaus: one observed after the peak and the other one appeared similar to 240 d later. Meanwhile, our NICER and XRT/Swift campaigns show two declines in the X-ray emission, one during the first optical plateau and one 70-90 d after the optical/UV decline. The evidence suggests that the optical/UV could not have been primarily originated from X-ray reprocessing. Furthermore, we detected a timelag of similar to 16-34 d between the optical and UV emission, which indicates the optical likely comes from UV reprocessing by a gas at a distance of 0.01-0.03 pc. We also report the first VLA and VLBA detection of this source at different frequencies and different stages of the second flare. The information obtained in the radio band - namely a steep and a late-time inverted radio spectrum, a high brightness temperature and a radio-loud state at late times - together with the multiwavelength properties of AT 2019avd suggests the launching and evolution of outflows such as disc winds or jets. In conclusion, we propose that after the ignition of black hole activity in the first flare, a super-Eddington flaring accretion disc formed and settled to a sub-Eddington state by the end of the second flare, associated with a compact radio outflow.

accretion discs

black hole physics

galaxies: nuclei

radio continuum: transients

accretion

galaxies: active

Författare

Yanan Wang

University of Southampton

Ranieri D. Baldi

University of Southampton

Istituto nazionale di astrofisica (INAF)

Santiago Del Palacio

Chalmers, Rymd-, geo- och miljövetenskap, Astronomi och plasmafysik

Muryel Guolo

Johns Hopkins University

Xiaolong Yang

Chinese Academy of Sciences

Yangkang Zhang

Chinese Academy of Sciences

Chris Done

Durham University

Dheeraj R. Pasham

Massachusetts Institute of Technology (MIT)

Erlin Qiao

Chinese Academy of Sciences

Ning Jiang

University of Science and Technology of China

Hongliang Yan

Chinese Academy of Sciences

Francesca Panessa

Istituto nazionale di astrofisica (INAF)

Chichuan Jin

Chinese Academy of Sciences

Rongfeng Shen

Sun Yat-Sen University

Lixin Dai

The University of Hong Kong

Monthly Notices of the Royal Astronomical Society

0035-8711 (ISSN) 1365-2966 (eISSN)

Vol. 520 2 2417-2435

Ämneskategorier

Subatomär fysik

Astronomi, astrofysik och kosmologi

Atom- och molekylfysik och optik

Annan fysik

DOI

10.1093/mnras/stad101

Mer information

Senast uppdaterat

2024-03-15