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 Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

The X-ray emission mechanism in large-scale jets of powerful radio quasarshas been a source of debate in recent years, with two competinginterpretations: either the X-rays are of synchrotron origin, arising from adifferent electron energy distribution than that producing the radio to opticalsynchrotron component, or they are due to inverse Compton scattering of cosmicmicrowave background photons (IC/CMB) by relativistic electrons in a powerfulrelativistic jet with bulk Lorentz factor Gamma ~ 10-20. These two models implyradically different conditions in the large-scale jet in terms of jet speed,kinetic power, and maximum energy of the particle acceleration mechanism, withimportant implications for the impact of the jet on the large-scaleenvironment. A large part of the X-ray origin debate has centered on thewell-studied source 3C 273. Here we present new observations from Fermi whichput an upper limit on the gamma-ray flux from the large-scale jet of 3C 273that violates at a confidence greater that 99.9% the flux expected from theIC/CMB X-ray model found by extrapolation of the UV to X-ray spectrum of knotA, thus ruling out the IC/CMB interpretation entirely for this source whencombined with previous work. Further, this upper limit from Fermi puts a limiton the Doppler beaming factor of at least delta < 9, assuming equipartitionfields, and possibly as low as delta < 5, assuming no major deceleration of thejet from knots A through D1.

Fermi Rules Out the IC/CMB Model for the Large Scale Jet X-ray Emission of 3C 273