Speaker
Description
The X-ray emission from resolved knots in the jets of many blazar cannot be explained as a simple extension of the radio synchrotron spectrum. So far no general consensus could be reached on the relative importance of the different broadband-emission mechanisms at play. In particular, observing the low radio frequencies provide valuable constraints to test different emission models like IC/CMB, Synchrotron Self Compton(SSC) or second synchrotron peak. We aim to study a sample of blazars featuring X-ray emitting jets, the morphology of which can be sampled with LOFAR-VLBI. We present ongoing analysis and results on the first object in this sample, OJ287. The long international baselines of LOFAR allow us to spatially resolve the individual X-ray emitting jet knots at ~140MHz and to probe the previously inaccessible part of the low-energy electron population. In combination with shorter-wavelength radio in the VLA GHz regime and Chandra X-ray data, the LOFAR-VLBI data will help test and constrain the above-mentioned different emission models. Here, we present results from this project with a focus on the LOFAR-VLBI sub-arcsecond resolution image of the X-ray jet in OJ287, resolving the kiloparsec knots in the jet. Furthermore, we present broadband SED modeling analysis for these knots, thereby understanding the physical properties of the underlying electron population.
