Fermi -LAT and Suzaku observations of the radio galaxy Centaurus B

J. Katsuta, Y. T. Tanaka, L. Stawarz, S. P. O'Sullivan, C. C. Cheung, Jun Kataoka, S. Funk, T. Yuasa, H. Odaka, T. Takahashi, J. Svoboda

    Research output: Contribution to journalArticle

    14 Citations (Scopus)

    Abstract

    Centaurus B is a nearby radio galaxy positioned in the southern hemisphere close to the Galactic plane. Here we present a detailed analysis of about 43 months of accumulated Fermi-LAT data of the γ-ray counterpart of the source initially reported in the 2nd Fermi-LAT catalog, and of newly acquired Suzaku X-ray data. We confirm its detection at GeV photon energies and analyze the extension and variability of the γ-ray source in the LAT dataset, in which it appears as a steady γ-ray emitter. The X-ray core of Centaurus B is detected as a bright source of a continuum radiation. We do not detect, however, any diffuse X-ray emission from the known radio lobes, with the provided upper limit only marginally consistent with the previously claimed ASCA flux. Two scenarios that connect the X-ray and γ-ray properties are considered. In the first one, we assume that the diffuse non-thermal X-ray emission component is not significantly below the derived Suzaku upper limit. In this case, modeling the inverse-Compton emission shows that the observed γ-ray flux of the source may in principle be produced within the lobes. This association would imply that efficient in-situ acceleration of the radiating electrons is occurring and that the lobes are dominated by the pressure from the relativistic particles. In the second scenario, with the diffuse X-ray emission well below the Suzaku upper limits, the lobes in the system are instead dominated by the magnetic pressure. In this case, the observed γ-ray flux is not likely to be produced within the lobes, but instead within the nuclear parts of the jet. By means of synchrotron self-Compton modeling, we show that this possibility could be consistent with the broad-band data collected for the unresolved core of Centaurus B, including the newly derived Suzaku spectrum.

    Original languageEnglish
    Article numberA66
    JournalAstronomy and Astrophysics
    Volume550
    DOIs
    Publication statusPublished - 2013

    Fingerprint

    radio galaxies
    rays
    lobes
    radio
    x rays
    broadband data
    relativistic particles
    Southern Hemisphere
    modeling
    catalogs
    synchrotrons
    emitters
    continuums
    broadband
    electron
    photons
    radiation
    energy
    electrons

    Keywords

    • Acceleration of particles
    • Galaxies: individual: Centaurus B
    • Galaxies: jets
    • Gamma rays: galaxies
    • Radiation mechanisms: non-thermal
    • X-rays: galaxies

    ASJC Scopus subject areas

    • Astronomy and Astrophysics
    • Space and Planetary Science

    Cite this

    Katsuta, J., Tanaka, Y. T., Stawarz, L., O'Sullivan, S. P., Cheung, C. C., Kataoka, J., ... Svoboda, J. (2013). Fermi -LAT and Suzaku observations of the radio galaxy Centaurus B. Astronomy and Astrophysics, 550, [A66]. https://doi.org/10.1051/0004-6361/201220270

    Fermi -LAT and Suzaku observations of the radio galaxy Centaurus B. / Katsuta, J.; Tanaka, Y. T.; Stawarz, L.; O'Sullivan, S. P.; Cheung, C. C.; Kataoka, Jun; Funk, S.; Yuasa, T.; Odaka, H.; Takahashi, T.; Svoboda, J.

    In: Astronomy and Astrophysics, Vol. 550, A66, 2013.

    Research output: Contribution to journalArticle

    Katsuta, J, Tanaka, YT, Stawarz, L, O'Sullivan, SP, Cheung, CC, Kataoka, J, Funk, S, Yuasa, T, Odaka, H, Takahashi, T & Svoboda, J 2013, 'Fermi -LAT and Suzaku observations of the radio galaxy Centaurus B', Astronomy and Astrophysics, vol. 550, A66. https://doi.org/10.1051/0004-6361/201220270
    Katsuta, J. ; Tanaka, Y. T. ; Stawarz, L. ; O'Sullivan, S. P. ; Cheung, C. C. ; Kataoka, Jun ; Funk, S. ; Yuasa, T. ; Odaka, H. ; Takahashi, T. ; Svoboda, J. / Fermi -LAT and Suzaku observations of the radio galaxy Centaurus B. In: Astronomy and Astrophysics. 2013 ; Vol. 550.
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    abstract = "Centaurus B is a nearby radio galaxy positioned in the southern hemisphere close to the Galactic plane. Here we present a detailed analysis of about 43 months of accumulated Fermi-LAT data of the γ-ray counterpart of the source initially reported in the 2nd Fermi-LAT catalog, and of newly acquired Suzaku X-ray data. We confirm its detection at GeV photon energies and analyze the extension and variability of the γ-ray source in the LAT dataset, in which it appears as a steady γ-ray emitter. The X-ray core of Centaurus B is detected as a bright source of a continuum radiation. We do not detect, however, any diffuse X-ray emission from the known radio lobes, with the provided upper limit only marginally consistent with the previously claimed ASCA flux. Two scenarios that connect the X-ray and γ-ray properties are considered. In the first one, we assume that the diffuse non-thermal X-ray emission component is not significantly below the derived Suzaku upper limit. In this case, modeling the inverse-Compton emission shows that the observed γ-ray flux of the source may in principle be produced within the lobes. This association would imply that efficient in-situ acceleration of the radiating electrons is occurring and that the lobes are dominated by the pressure from the relativistic particles. In the second scenario, with the diffuse X-ray emission well below the Suzaku upper limits, the lobes in the system are instead dominated by the magnetic pressure. In this case, the observed γ-ray flux is not likely to be produced within the lobes, but instead within the nuclear parts of the jet. By means of synchrotron self-Compton modeling, we show that this possibility could be consistent with the broad-band data collected for the unresolved core of Centaurus B, including the newly derived Suzaku spectrum.",
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    AU - Tanaka, Y. T.

    AU - Stawarz, L.

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    AU - Cheung, C. C.

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    AU - Funk, S.

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    AB - Centaurus B is a nearby radio galaxy positioned in the southern hemisphere close to the Galactic plane. Here we present a detailed analysis of about 43 months of accumulated Fermi-LAT data of the γ-ray counterpart of the source initially reported in the 2nd Fermi-LAT catalog, and of newly acquired Suzaku X-ray data. We confirm its detection at GeV photon energies and analyze the extension and variability of the γ-ray source in the LAT dataset, in which it appears as a steady γ-ray emitter. The X-ray core of Centaurus B is detected as a bright source of a continuum radiation. We do not detect, however, any diffuse X-ray emission from the known radio lobes, with the provided upper limit only marginally consistent with the previously claimed ASCA flux. Two scenarios that connect the X-ray and γ-ray properties are considered. In the first one, we assume that the diffuse non-thermal X-ray emission component is not significantly below the derived Suzaku upper limit. In this case, modeling the inverse-Compton emission shows that the observed γ-ray flux of the source may in principle be produced within the lobes. This association would imply that efficient in-situ acceleration of the radiating electrons is occurring and that the lobes are dominated by the pressure from the relativistic particles. In the second scenario, with the diffuse X-ray emission well below the Suzaku upper limits, the lobes in the system are instead dominated by the magnetic pressure. In this case, the observed γ-ray flux is not likely to be produced within the lobes, but instead within the nuclear parts of the jet. By means of synchrotron self-Compton modeling, we show that this possibility could be consistent with the broad-band data collected for the unresolved core of Centaurus B, including the newly derived Suzaku spectrum.

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    KW - X-rays: galaxies

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