Jets in FR0 radio galaxies

Context. The local radio-loud AGN population is dominated by compact sources named FR0s. These show features, for example the host type, mass of supermassive black hole (SMBH), and multi-band nuclear characteristics, that are similar to those FRI radio galaxies. However, in band, while FR0 share same properties, kiloparsec-scale diffuse component dominant missing Previous very-long-baseline interferometry (VLBI) observations a small sample FR0s complex structure, mostly symmetric (two-sided jets) with respect central core. Aims. With this project we would like study parsec-scale structure comparison sources. Jets relativistic on parsec scale decrease their velocity becoming subrelativistic kiloparsec scale. We test whether result also applies jets or, alternatively, they This might be reason why unable grow, because instabilities, related low jet bulk velocity. Methods. To end observed 18 galaxies VLBA at 1.5 5 GHz and/or EVN 1.7 produced detailed images milliarcsec resolution emission core structure. Results. All have been detected but one. Four unresolved, even these high-resolution images; all other derived distribution jet-to-counter-jet ratio found it significantly different from FRIs, suggesting speed velocities. Conclusions. Combining present data published VLBI observations, derive shows strong evidence mildly order 0.5c or less. A thin inner spine surrounded low-velocity sheath could agreement SMBH launch region properties.