Archive abstract

Abstract of the proposal for the experiment EM137


The transient AT2018cow was discovered on 16th June 2018, offset by 1.7 kpc from the core of galaxy CGCG 137-068 (distance ~ 60 Mpc). Multi-wavelength observations suggest a variety of progenitors (e.g. peculiar supernovae, gamma-ray burst, tidal disruption event), and indicate the prominent influence of a central engine, thus offering an inconclusive picture but a promising opportunity for continued high-resolution VLBI monitoring observations. The source is detected (unresolved) in our recent L-band e-EVN (October 2018) and C-band EVN (November 2018) observations with increasing astrometric accuracy, enabling the characterization of the source morphology and its evolution. Another deep C-band EVN observation currently scheduled for the 1/2019 session can potentially detect a discernable shift in the emission peak and hence constrain proper motion. As the source continues to brighten in the GHz frequencies, we propose another epoch of C-band EVN observations (12-hour; 2/2019 session) to better understand the afterglow and provide strict constraints on the proper motion (> 0.15 mas/yr can be detected with three continuous EVN sessions epochs). The emission structure (jetted or expanding source) and progenitor nature can thus be clarified.
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