English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

The physical origin of the X-ray emission in powerful quasar jets has been along-standing mystery. Though these jets start out on the sub-pc scale ashighly relativistic flows, we do not have any direct measurement of theirspeeds on the kpc scale, where the vast distances from the core necessitate insitu particle acceleration. If the jets remain highly relativistic on kpcscales, then the X-rays could be due to inverse-Compton upscattering of CMBphotons. However, the IC/CMB explanation predicts a high level of gamma-rayemission, which should be detectible by the Fermi/LAT. We have searched for andruled out this emission at a high level of significance for the well-knownsources 3C 273 and PKS 0637-752, suggesting the X-rays are synchrotron, thoughof unknown origin. These recent results with Fermi also suggest that thekpc-scale jets in powerful quasars are significantly slower than have beenpresumed under the IC/CMB model. I will discuss the surprising implications ofthese findings for the energetics and radiative output of powerful quasars aswell as their impact on their environment.

Missing Gamma-Rays from kpc-scale AGN Jets: A Test of the IC/CMB Model