DOI

https://doi.org/10.48717/7e11-mk34

Project

EW052

Title

e-EVN: EW052A, EW052A, EP134D, EB115D

Abstract

Extremely Stable Quasars (ESQs) are a rare population of type 1 quasars recently discovered to exhibit unusually weak optical variability, and a statistically significant radio excess which suggests the presence of intermediate-power jets. It has been proposed that ESQs may host ultra-strong magnetic fields near their central engines, which suppress magnetorotational instability in the inner accretion disk and simultaneously facilitate jet launching. We propose simultaneous 1.7 GHz + 5 GHz EVN observations of 8 ESQs, which were previously imaged at 1.7 GHz in our EVN program and found to exhibit compact radio cores with unusually large positional offsets (> 7 mas) from their Gaia optical centroids. We aim to investigate the origin of these large offsets, including the possibility that they arise from extreme core shifts-potentially linked to exceptionally strong magnetic fields in the jet-launching region-as well as alternative explanations such as compact jet knots or off-nucleus AGNs, which are also scientifically compelling. This pilot study will identify the best candidates for future multi-frequency VLBI observations to precisely measure core shifts and magnetic fields, potentially revealing the most extreme cases ever seen in quasars. We request a total observing time of 32 hours.