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Title: 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

Abstract

In this paper, we present multi-wavelength monitoring results for the broad-line radio galaxy 3C 120 in the MeV/GeV, sub-millimeter, and 43 GHz bands over 6 yr. Over the past 2 yr, the Fermi-Large Area Telescope sporadically detected 3C 120 with high significance and the 230 GHz data also suggest an enhanced activity of the source. After the MeV/GeV detection from 3C 120 in MJD 56240–56300, 43 GHz Very Long Baseline Array (VLBA) monitoring revealed a brightening of the radio core, followed by the ejection of a superluminal knot. Since we observed the γ-ray and VLBA phenomena in temporal proximity to each other, it is naturally assumed that they are physically connected. This assumption was further supported by the subsequent observation that the 43 GHz core brightened again after a γ-ray flare occurred around MJD 56560. We can then infer that the MeV/GeV emission took place inside an unresolved 43 GHz core of 3C 120 and that the jet dissipation occurred at sub-parsec distances from the central black hole (BH), if we take the distance of the 43 GHz core from the central BH as ~0.5 pc, as previously estimated from the time lag between X-ray dips and knot ejections. Basedmore » on our constraints on the relative locations of the emission regions and energetic arguments, we conclude that the γ rays are more favorably produced via the synchrotron self-Compton process, rather than inverse Compton scattering of external photons coming from the broad line region or hot dusty torus. Finally, we also derived the electron distribution and magnetic field by modeling the simultaneous broadband spectrum.« less

Authors:
 [1];  [2];  [2];  [3]; ORCiD logo [4];  [5];  [6];  [7];  [7];  [5]
  1. Hiroshima University (Japan). Hiroshima Astrophysical Science Center
  2. Institute of Space and Astronautical Science (Japan)
  3. Naval Research Laboratory, Washington, DC (United States). Space Science Division
  4. Institute of Space and Astronautical Science (Japan) ; Jagiellonian University (Poland). Astronomical Observatory
  5. Hiroshima University (Japan). Department of Physical Sciences
  6. Harvard-Smithsonian Center for Astrophysics, Cambridge, MA (United States)
  7. Waseda University, Tokyo (Japan). Research Institute for Science and Engineering
Publication Date:
Research Org.:
SLAC National Accelerator Lab., Menlo Park, CA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1355174
Grant/Contract Number:  
AC02-76SF00515
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
The Astrophysical Journal. Letters
Additional Journal Information:
Journal Volume: 799; Journal Issue: 2; Journal ID: ISSN 2041-8213
Publisher:
Institute of Physics (IOP)
Country of Publication:
United States
Language:
English
Subject:
79 ASTRONOMY AND ASTROPHYSICS; radiation mechanisms; non-thermal — galaxies; active — galaxies; jets — gamma rays; galaxies — radio continuum; galaxies — galaxies; individual (3C 120)

Citation Formats

Tanaka, Y. T., Doi, A., Inoue, Y., Cheung, C. C., Stawarz, L., Fukazawa, Y., Gurwell, M. A., Tahara, M., Kataoka, J., and Itoh, R. 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. United States: N. p., 2015. Web. doi:10.1088/2041-8205/799/2/L18.
Tanaka, Y. T., Doi, A., Inoue, Y., Cheung, C. C., Stawarz, L., Fukazawa, Y., Gurwell, M. A., Tahara, M., Kataoka, J., & Itoh, R. 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. United States. doi:10.1088/2041-8205/799/2/L18.
Tanaka, Y. T., Doi, A., Inoue, Y., Cheung, C. C., Stawarz, L., Fukazawa, Y., Gurwell, M. A., Tahara, M., Kataoka, J., and Itoh, R. Fri . "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". United States. doi:10.1088/2041-8205/799/2/L18. https://www.osti.gov/servlets/purl/1355174.
@article{osti_1355174,
title = {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},
author = {Tanaka, Y. T. and Doi, A. and Inoue, Y. and Cheung, C. C. and Stawarz, L. and Fukazawa, Y. and Gurwell, M. A. and Tahara, M. and Kataoka, J. and Itoh, R.},
abstractNote = {In this paper, we present multi-wavelength monitoring results for the broad-line radio galaxy 3C 120 in the MeV/GeV, sub-millimeter, and 43 GHz bands over 6 yr. Over the past 2 yr, the Fermi-Large Area Telescope sporadically detected 3C 120 with high significance and the 230 GHz data also suggest an enhanced activity of the source. After the MeV/GeV detection from 3C 120 in MJD 56240–56300, 43 GHz Very Long Baseline Array (VLBA) monitoring revealed a brightening of the radio core, followed by the ejection of a superluminal knot. Since we observed the γ-ray and VLBA phenomena in temporal proximity to each other, it is naturally assumed that they are physically connected. This assumption was further supported by the subsequent observation that the 43 GHz core brightened again after a γ-ray flare occurred around MJD 56560. We can then infer that the MeV/GeV emission took place inside an unresolved 43 GHz core of 3C 120 and that the jet dissipation occurred at sub-parsec distances from the central black hole (BH), if we take the distance of the 43 GHz core from the central BH as ~0.5 pc, as previously estimated from the time lag between X-ray dips and knot ejections. Based on our constraints on the relative locations of the emission regions and energetic arguments, we conclude that the γ rays are more favorably produced via the synchrotron self-Compton process, rather than inverse Compton scattering of external photons coming from the broad line region or hot dusty torus. Finally, we also derived the electron distribution and magnetic field by modeling the simultaneous broadband spectrum.},
doi = {10.1088/2041-8205/799/2/L18},
journal = {The Astrophysical Journal. Letters},
number = 2,
volume = 799,
place = {United States},
year = {Fri Jan 23 00:00:00 EST 2015},
month = {Fri Jan 23 00:00:00 EST 2015}
}

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