Authors: B. Marcote, M. Giroletti, M. A. Garrett, Z. Paragi, J. Yang, K. Hada, T. W. B. Muxlow, C. C. Cheung
Journal: Transactions of IAA RAS vol. 41
Pages: 18 - 22
Keywords: galaxies: active, VLBI
FRB 150418 is the first fast radio bursts claimed to be localized. Keane et al. (2016) reported its association with a radio transient source hosted by an elliptical galaxy, WISE J0716−1900, located at a distance of z = 0.492 ± 0.008. However, this association has been questioned with recent VLA observations, which would support that the transient source is actually an active galactic nucleus (AGN) and thus unlinked with the origin of FRB 150418. Here we present the observations conducted with the European VLBI Network (EVN) at 5.0 GHz at four different epochs, together with three simultaneous e-MERLIN observations, to clarify the origin of the transient source located in WISE J0716−1900. We report a compact radio source on milliarcsecond scales with a persistent flux density of 115 ± 9 µJy beam¯¹, which implies a luminosity of (1.13 ± 0.15) × 10²³ W Hz¯¹ given the distance of the galaxy. Additionally, the compactness of the source allows us to estimate a brightness temperature of Tb ≥ 10⁸·⁵ K. These results are consistent with a scintillating low-luminosity AGN located in the center of WISE J0716 − 1900.