Archive abstract

Abstract of the proposal for the experiment EY033A

The transient AT2018cow was discovered on 16th June 2018, being offset by 1.7 kpc from the core of galaxy CGCG 137-068 (distance ~ 60 Mpc). Multi-wavelength observations from the time of discovery indicate a puzzling source nature, with an initial identification as a SN Ic changing to one hosting a gamma ray burst or a tidal disruption event involving an intermediate mass black hole, thus necessitating further monitoring to distinguish between them. Owing to the source being detected (though unresolved) in our recent L-band pilot EVN observations (and forthcoming higher mas-resolution C-band EVN observations), and it becoming brighter in the GHz-radio frequencies likely due to synchrotron emission processes, we propose continued VLBI observations of this source at 5 GHz in two staggered epochs (2-hour e-EVN plus 12-hour full EVN trigger observations) in order to study the afterglow nature. As the source is relatively nearby, this is expected to yield unique information on the source structure, proper motion and flux density which can enable the construction of the evolving spectrum and light curve and help elucidate the true nature of AT2018cow.
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