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تسجيل مستخدم جديدModeling the 3C 120 Radio Jet from 1 to 30 Milliarcseconds
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The predicted spatial development of helical structures along an expanding jet are used to model observed structures and motions in the 3C 120 jet. Proper motions of helical components associated with the pattern and of other components that move through the pattern provide estimates of flow and helical pattern speeds. Theoretical modeling allows determination of sound speeds as a function of jet viewing angle. Jet morphology argues against viewing angles larger than 12 deg. At a 12 deg viewing angle the most likely scenario involves a decline in jet sound speed from c/3 < a_j < c/1.7 at ~0.5 mas from the core to 0.1c < a_j < 0.25c at ~25 mas from the core accompanied by some acceleration in the jet flow from Lorentz factor < 5 to Lorentz factor > 7. At smaller viewing angles the jet sound speed is lower and at a 6 deg viewing angle the jet sound speed is about a factor 2 less but the flow Lorentz factor is comparable. The decline in radio intensity is on the order of what would be associated with isothermal jet expansion. Knot interknot intensity variations are greater than would be expected from adiabatic compressions associated with the helical twist and we infer the presence of a shock along the leading edge of the helical twist. Our results imply that the macroscopic heating of the expanding jet fluid is less than the microscopic energization of the synchrotron radiating relativistic electrons.
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We present the results of extensive multi-frequency monitoring of the radio galaxy 3C 120 between 2002 and 2007 at X-ray, optical, and radio wave bands, as well as imaging with the Very Long Baseline Array (VLBA). Over the 5 yr of observation, signif
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We present the analysis of the radio jet evolution of the radio galaxy 3C 120 during a period of prolonged gamma-ray activity detected by the Fermi satellite between December 2012 and October 2014. We find a clear connection between the gamma-ray and
radio emission, such that every period of gamma-ray activity is accompanied by the flaring of the mm-VLBI core and subsequent ejection of a new superluminal component. However, not all ejections of components are associated with gamma-ray events detectable by Fermi. Clear gamma-ray detections are obtained only when components are moving in a direction closer to our line of sight.This suggests that the observed gamma-ray emission depends not only on the interaction of moving components with the mm-VLBI core, but also on their orientation with respect to the observer. Timing of the gamma-ray detections and ejection of superluminal components locate the gamma-ray production to within almost 0.13 pc from the mm-VLBI core, which was previously estimated to lie about 0.24 pc from the central black hole. This corresponds to about twice the estimated extension of the broad line region, limiting the external photon field and therefore suggesting synchrotron self Compton as the most probable mechanism for the production of the gamma-ray emission. Alternatively, the interaction of components with the jet sheath can provide the necessary photon field to produced the observed gamma-rays by Compton scattering.
We present the spectral analysis of a 200~ks observation of the broad-line radio galaxy 3C~120 performed with the high energy transmission grating (HETG) spectrometer on board the emph{Chandra} X-ray Observatory. We find (i) a neutral absorption comp
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