The Radio Structure of High-Energy-Peaked BL Lacertae Objects

We present VLA and first-epoch VLBA observations that are part of a program to study the parsec-scale radio structure of a sample of 15 high-energy–peaked BL Lacertae objects (HBLs). The sample was chosen to span the range of logarithmic X-ray to radio flux ratios observed in HBLs. As this is only the first epoch of observations, proper motions of jet components are not yet available; thus, we consider only the structure and alignment of the parsec- and kiloparsec-scale jets. Like most low-energy–peaked BL Lacertae objects (LBLs), our HBL sample shows parsec-scale core-jet morphologies and compact, complex kiloparsec-scale morphologies. Some objects also show evidence for bending of the jet 10–20 pc from the core, suggesting interaction of the jet with the surrounding medium. Whereas LBLs show a wide distribution of parsec- to kiloparsec-scale jet misalignment angles, there is weak evidence that the jets in HBLs are more well aligned, suggesting that HBL jets are either intrinsically straighter or are seen further off-axis than LBL jets.