DOI

https://doi.org/10.48717/xcs5-fs51

Project

EH036

Title

First-epoch VLBI of HE0435

Abstract

Strong gravitational lensing can be used to observe otherwise undetectable background sources, thanks to the magnifying power of the lensing mass. We have previously used this property in combination with the EVN to image the faintest ever radio source and resolve its structure to the sub-parsec scale (Hartley et al, 2019). This observation was part of a programme to understand the radio emission mechanisms involved in radio quiet quasars (RQQ), using lenses as cosmic telescopes in order to directly image otherwise unseen radio emission. While statistical studies by some authors have found evidence that starburst activity dominates the emission in this population, others have shown that RQQs simply represent a continuum of AGN activity, with jets ranging in size from radio loud quasar scales and down. Our previous observation found direct evidence for jets as the dominant source of emission, and observations of two more lensed RQQs also show evidence of AGN activity. We wish to expand our sample to include all quadruply imaged RQQs above -15 Dec in order to begin using our observations to statistically constrain the RQQ problem. A non-detection would provide a robust rejection of AGN activity in this case.