THE CONNECTION BETWEEN THE RADIO JET AND THE GAMMA-RAY EMISSION IN THE RADIO GALAXY 3C 120
- Instituto de Astrofísica de Andalucía, CSIC, Apartado 3004, E-18080, Granada (Spain)
- Istituto Nazionale di Astrofisica-IASFBO, Via Gobetti 101, I-40129, Bologna (Italy)
- Institute for Astrophysical Research, Boston University, 725 Commonwealth Avenue, Boston, MA 02215 (United States)
- Department of Physics, Purdue University, 525 Northwestern Avenue, West Lafayette, IN 47907 (United States)
- Astro Space Center, Lebedev Physical Institute, Russian Academy of Sciences, Profsoyuznaya str. 84/32, Moscow 117997 (Russian Federation)
- Aalto University Metsähovi Radio Observatory, Metsähovintie 114, FI-02540 Kylmälä (Finland)
- Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, D-53121 Bonn (Germany)
We present the analysis of the radio jet evolution of the radio galaxy 3C 120 during a period of prolonged γ-ray activity detected by the Fermi satellite between 2012 December and 2014 October. We find a clear connection between the γ-ray and radio emission, such that every period of γ-ray activity is accompanied by the flaring of the millimeter very long baseline interferometry (VLBI) core and subsequent ejection of a new superluminal component. However, not all ejections of components are associated with γ-ray events detectable by Fermi. Clear γ-ray detections are obtained only when components are moving in a direction closer to our line of sight. This suggests that the observed γ-ray emission depends not only on the interaction of moving components with the millimeter VLBI core, but also on their orientation with respect to the observer. Timing of the γ-ray detections and ejection of superluminal components locate the γ-ray production to within ∼0.13 pc from the millimeter 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 γ-ray emission. Alternatively, the interaction of components with the jet sheath can provide the necessary photon field to produced the observed γ-rays by Compton scattering.
- OSTI ID:
- 22525671
- Journal Information:
- Astrophysical Journal, Vol. 808, Issue 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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SIX YEARS OF FERMI-LAT AND MULTI-WAVELENGTH MONITORING OF THE BROAD-LINE RADIO GALAXY 3C 120: JET DISSIPATION AT SUB-PARSEC SCALES FROM THE CENTRAL ENGINE
The γ-ray emission region in the Fanaroff-Riley II radio galaxy 3C 111