Evolution of and high-energy emission from GHz-peaked spectrum sources

Stawarz, L. Ostorero, M. C. Begelman, R. Moderski, J. Kataoka, S. Wagners

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Abstract

Here we discuss evolution and broadband emission of compact (<kpc) lobes in young radio sources. We propose a simple dynamical description for these objects, consisting of a relativistic jet propagating into a uniform gaseous medium in the central parts of an elliptical host. In the framework of the proposed model we follow the evolution of ultrarelativistic electrons injected from a terminal hot spot of a jet to expanding lobes, taking into account their adiabatic energy losses, as well as radiative cooling. This allows us to discuss the broadband lobe emission of young radio sources. In particular, we argue that the observed spectral turnover in the radio synchrotron spectra of these objects cannot originate from the synchrotron self-absorption process but is most likely due to free-free absorption effects connected with neutral clouds of interstellar medium engulfed by the expanding lobes and photoionized by active centers. We also find a relatively strong and complex high-energy emission component produced by inverse Compton upscattering of various surrounding photon fields by the lobes' electrons. We argue that such high-energy radiation is strong enough to account for several observed properties of GHz-peaked spectrum (GPS) radio galaxies at UV and X-ray frequencies. In addition, this emission is expected to extend up to GeV (or possibly even TeV) photon energies and can thus be probed by several modem 7-ray instruments. In particular, we suggest that GPS radio galaxies should constitute a relatively numerous class of extragalactic sources detected by GLAST.

Original languageEnglish
Pages (from-to)911-925
Number of pages15
JournalAstrophysical Journal
Volume680
Issue number2
DOIs
Publication statusPublished - 2008 Jun 20

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Keywords

  • Acceleration of particles
  • Galaxies: active
  • Galaxies: jets
  • Radiation mechanisms: nonthermal

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this

Stawarz, Ostorero, L., Begelman, M. C., Moderski, R., Kataoka, J., & Wagners, S. (2008). Evolution of and high-energy emission from GHz-peaked spectrum sources. Astrophysical Journal, 680(2), 911-925. https://doi.org/10.1086/587781