A novel approach in constraining electron spectra in blazar jets: The case of markarian 421

Masayoshi Ushio, Łukasz Stawarz, Tadayuki Takahashi, David Paneque, Grzegorz Madejski, Masaaki Hayashida, Jun Kataoka, Yasuyuki T. Tanaka, Takaaki Tanaka, Michałl Ostrowski

    研究成果: Article

    13 引用 (Scopus)

    抄録

    We report results from the observations of the well-studied TeV blazar Mrk 421 with the Swift and the Suzaku satellites in 2008 December. During the observation, Mrk 421 was found in a relatively low activity state, with the corresponding 2-10 keV flux of 3 × 10-10 erg s-1 cm-2. For the purpose of robustly constraining the UV-to-X-ray emission continuum we selected only the data corresponding to truly simultaneous time intervals between Swift and Suzaku, allowing us to obtain a good-quality, broadband spectrum despite a modest length (0.6 ks) exposure. We analyzed the spectrum with the parametric forward-fitting SYNCHROTRON model implemented in XSPEC assuming two different representations of the underlying electron energy distribution, both well motivated by the current particle acceleration models: a power-law distribution above the minimum energy γmin with an exponential cutoff at the maximum energy γmax, and a modified ultra-relativistic Maxwellian with an equilibrium energy γeq. We found that the latter implies unlikely physical conditions within the blazar zone of Mrk 421. On the other hand, the exponentially moderated power-law electron distribution gives two possible sets of the model parameters: (1) flat spectrum dN'e/dγ α γ-1.91 with low minimum electron energy γmin × 103, and (2) steep spectrum α γ-2.77 with high minimum electron energy γmin ∼2× 104. We discuss different interpretations of both possibilities in the context of a diffusive acceleration of electrons at relativistic, sub-or superluminal shocks. We also comment on exactly how the γ-ray data can be used to discriminate between the different proposed scenarios.

    元の言語English
    ページ(範囲)1509-1516
    ページ数8
    ジャーナルAstrophysical Journal
    724
    発行部数2
    DOI
    出版物ステータスPublished - 2010 12 1

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    electron
    electron energy
    energy
    electrons
    particle acceleration
    electron distribution
    rays
    energy distribution
    power law distribution
    cut-off
    shock
    continuums
    broadband
    intervals
    erg
    power law
    x rays
    distribution

    ASJC Scopus subject areas

    • Space and Planetary Science
    • Astronomy and Astrophysics

    これを引用

    Ushio, M., Stawarz, Ł., Takahashi, T., Paneque, D., Madejski, G., Hayashida, M., ... Ostrowski, M. (2010). A novel approach in constraining electron spectra in blazar jets: The case of markarian 421. Astrophysical Journal, 724(2), 1509-1516. https://doi.org/10.1088/0004-637X/724/2/1509

    A novel approach in constraining electron spectra in blazar jets : The case of markarian 421. / Ushio, Masayoshi; Stawarz, Łukasz; Takahashi, Tadayuki; Paneque, David; Madejski, Grzegorz; Hayashida, Masaaki; Kataoka, Jun; Tanaka, Yasuyuki T.; Tanaka, Takaaki; Ostrowski, Michałl.

    :: Astrophysical Journal, 巻 724, 番号 2, 01.12.2010, p. 1509-1516.

    研究成果: Article

    Ushio, M, Stawarz, Ł, Takahashi, T, Paneque, D, Madejski, G, Hayashida, M, Kataoka, J, Tanaka, YT, Tanaka, T & Ostrowski, M 2010, 'A novel approach in constraining electron spectra in blazar jets: The case of markarian 421', Astrophysical Journal, 巻. 724, 番号 2, pp. 1509-1516. https://doi.org/10.1088/0004-637X/724/2/1509
    Ushio M, Stawarz Ł, Takahashi T, Paneque D, Madejski G, Hayashida M その他. A novel approach in constraining electron spectra in blazar jets: The case of markarian 421. Astrophysical Journal. 2010 12 1;724(2):1509-1516. https://doi.org/10.1088/0004-637X/724/2/1509
    Ushio, Masayoshi ; Stawarz, Łukasz ; Takahashi, Tadayuki ; Paneque, David ; Madejski, Grzegorz ; Hayashida, Masaaki ; Kataoka, Jun ; Tanaka, Yasuyuki T. ; Tanaka, Takaaki ; Ostrowski, Michałl. / A novel approach in constraining electron spectra in blazar jets : The case of markarian 421. :: Astrophysical Journal. 2010 ; 巻 724, 番号 2. pp. 1509-1516.
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    abstract = "We report results from the observations of the well-studied TeV blazar Mrk 421 with the Swift and the Suzaku satellites in 2008 December. During the observation, Mrk 421 was found in a relatively low activity state, with the corresponding 2-10 keV flux of 3 × 10-10 erg s-1 cm-2. For the purpose of robustly constraining the UV-to-X-ray emission continuum we selected only the data corresponding to truly simultaneous time intervals between Swift and Suzaku, allowing us to obtain a good-quality, broadband spectrum despite a modest length (0.6 ks) exposure. We analyzed the spectrum with the parametric forward-fitting SYNCHROTRON model implemented in XSPEC assuming two different representations of the underlying electron energy distribution, both well motivated by the current particle acceleration models: a power-law distribution above the minimum energy γmin with an exponential cutoff at the maximum energy γmax, and a modified ultra-relativistic Maxwellian with an equilibrium energy γeq. We found that the latter implies unlikely physical conditions within the blazar zone of Mrk 421. On the other hand, the exponentially moderated power-law electron distribution gives two possible sets of the model parameters: (1) flat spectrum dN'e/dγ α γ-1.91 with low minimum electron energy γmin × 103, and (2) steep spectrum α γ-2.77 with high minimum electron energy γmin ∼2× 104. We discuss different interpretations of both possibilities in the context of a diffusive acceleration of electrons at relativistic, sub-or superluminal shocks. We also comment on exactly how the γ-ray data can be used to discriminate between the different proposed scenarios.",
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    AU - Stawarz, Łukasz

    AU - Takahashi, Tadayuki

    AU - Paneque, David

    AU - Madejski, Grzegorz

    AU - Hayashida, Masaaki

    AU - Kataoka, Jun

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    KW - X-rays: galaxies

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