Landing page for project EM170

We propose to continue our astrometric monitoring program on the newly-detected relativistic tidal disruption event AT2022cmc. This is the first such event detected since 2012, and only the second studied in detail with VLBI. Such ``jetted" tidal disruption events are a rare subclass of highly-energetic tidal disruptions in which a relativistic jet is launched at a very low inclination to the line of sight. Our two early-time eEVN observations of the event (1.5 and 4.5 months post-discovery) provided a high-precision, early-time anchor on the source position. With two additional astrometric epochs over the next year, we aim to detect any jet motion, thereby constraining a combination of Lorentz factor and viewing angle. These data will complement ongoing multi-radio frequency monitoring of the event, helping to break modelling degeneracies and thereby determining the physical parameters of the jets. Two well-positioned background calibrator sources enable us to minimize systematic errors on the astrometry, providing excellent astrometric precision. A significant detection of jet motion with these high-precision astrometric observations would provide the first direct constraint on the Lorentz factor of a jet in a tidal disruption event.

This data is part of the archive of VLBI data maintained by JIVE on behalf of the EVN, a network of radio telescopes located primarily in Europe and Asia, with additional antennas in South Africa. The EVN archive itself has the DOI https://doi.org/10.17616/R3Z197