The radio jet of ultra-high-energy peaked BL Lac objects(UHBLs)

Abstract By using our one-epoch EVN+Merlin data and some archived VLBA data, we present the radio properties of 9 ultra-high-energy synchrotron peak BL Lacs (UHBLs) selected as all BL Lacs with log (νpeak/Hz)>20 from Nieppola et al. . Our results support that UHBLs might be the less Doppler beamed versions of HBLs with similar jet power.