The Nearby Luminous Transient AT2018cow: A Magnetar Formed in a Subrelativistically Expanding Nonjetted Explosion
Artikel i vetenskaplig tidskrift, 2020

The fast-rising blue optical transient AT2018cow indicated unusual early-phase characteristics unlike relatively better studied explosive transients. Its afterglow may be produced by either a relativistically beamed (jetted) or intrinsically luminous (nonjetted) ejecta and carries observational signatures of the progenitor and environment. High-resolution monitoring can distinguish between these scenarios and clarify the progenitor nature. We present very long baseline interferometry (VLBI) observations of AT2018cow at 5 GHz involving 21 radio telescopes from the European VLBI Network with five sessions spanning ≈1 yr. With an astrometric precision up to 25 μas per epoch, the rapidly fading compact mas-scale source is found to be nonjetted with a proper motion of ≤0.15 mas yr-1 (0.14 c). This and a dense (number density ≈104-105 cm-3) magnetized environment (magnetic field strength ≥0.84 G) are characteristic of a newly formed magnetar driven central engine, originating in the successful explosion of a low-mass star.


P. Mohan

Shanghai Astronomical Observatory

T. An

Shanghai Astronomical Observatory

Chinese Academy of Sciences

Jun Yang

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

Shanghai Astronomical Observatory

Astrophysical Journal Letters

2041-8205 (ISSN) 2041-8213 (eISSN)

Vol. 888 2 L24


Astronomi, astrofysik och kosmologi

Fusion, plasma och rymdfysik



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