2016A&A...593L..16G

Aims. We investigate the nature of the compact and possibly variable nuclear radio source in the centre of WISE J0716-19, the proposed host galaxy of the fast radio burst FRB 150418.
Methods. We observed WISE J0716-19 at 5.0GHz with the European VLBI Network (EVN) four times between 2016 March 16 and June 2. At three epochs, we simultaneously observed the source with e-MERLIN at the same frequency.
Results. We detected a compact source in the EVN data in each epoch with a significance of up to ∼8σ. The four epochs yielded consistent results within their uncertainties for the peak surface intensity and positions. The mean values for these quantities are I_peak=(115±9)µJy/beam and RA=07h16m34.55496(7)s, Dec=-19°00'39.4754(8)". The e-MERLIN data provided ∼3-5σ detections at a position consistent with those of the EVN data. The emission on angular scales intermediate between the EVN and e-MERLIN is consistent with being null. The brightness temperature of the EVN core is T_b≥10^8.5K, close to the value previously required to explain the short-term radio variability properties of WISE J0716-19 in terms of interstellar scintillation.
Conclusions. Our observations provide direct and independent evidence of a nuclear compact source in WISE J0716-19, a physical scenario without evident connection with FRB 150418. However, the EVN data do not indicate the variability observed with the VLA.