The evolution of the large-scale emission in FRI jets - Astrophysics > High Energy Astrophysical PhenomenaReport as inadecuate

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Abstract: Recent observations in X-rays and gamma-rays of nearby FRI radio galaxieshave raised the question of the origin of the emission detected in thetermination structures of their jets. The study of these structures can giveinformation on the conditions for particle acceleration and radiation at thefront shocks. In addition, an evolutionary scenario can help to disentangle theorigin of the detected X-ray emission in young FRI sources, like some GigahertzPeaked Spectrum AGNs. This work focuses on the nature and detectability of theradiation seen from the termination regions of evolving FRI jets. We use theresults of a relativistic, two-dimensional numerical simulation of thepropagation of an FRI jet, coupled with a radiation model, to make predictionsfor the spectra and lightcurves of the thermal and non-thermal emission atdifferent stages of the FRI evolution. Our results show that under moderatemagnetic fields, the synchrotron radiation would be the dominant non-thermalchannel, appearing extended in radio and more compact in X-rays, withrelatively small flux variations with time. The shocked jet synchrotronemission would dominate the X-ray band, although the shocked ISM-ICM thermalcomponent alone may be significant in old sources. Inverse Compton scatteringof CMB photons could yield significant fluxes in the GeV and TeV bands, with anon-negligible X-ray contribution. The IC radiation would present a biggerangular size in X-rays and GeV than in TeV, with fluxes increasing with time.We conclude that the thermal and non-thermal broadband emission from thetermination regions of FRI jets could be detectable for sources located up todistances of a few 100 Mpc.

Author: Pol Bordas, Valentí Bosch-Ramon, Manel Perucho


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