Suzaku X-ray imaging of the extended lobe in the giant radio galaxy NGC6251 associated with the fermi-lat source 2FGLJ1629.4+8236

Y. Takeuchi, Jun Kataoka, Stawarz, Y. Takahashi, Keiichi Maeda, T. Nakamori, C. C. Cheung, A. Celotti, Y. Tanaka, T. Takahashi

    Research output: Contribution to journalArticle

    17 Citations (Scopus)

    Abstract

    We report the results of a Suzaku X-ray imaging study of NGC6251, a nearby giant radio galaxy with intermediate FRI/II radio properties. Our pointing direction was centered on the γ-ray emission peak recently discovered with the Fermi Large Area Telescope (LAT) around the position of the northwest (NW) radio lobe 15 arcmin offset from the nucleus. After subtracting two "off-source" pointings adjacent to the radio lobe and removing possible contaminants in the X-ray Imaging Spectrometer field of view, we found significant residual X-ray emission most likely diffuse in nature. The spectrum of the excess X-ray emission is well fitted by a power law with a photon index Γ = 1.90 ± 0.15 and a 0.5-8keV flux of 4 × 10 -13ergcm-2s-1. We interpret this diffuse X-ray emission component as being due to inverse Compton upscattering of the cosmic microwave background photons by ultrarelativistic electrons within the lobe, with only a minor contribution from the beamed emission of the large-scale jet. Utilizing archival radio data for the source, we demonstrate by means of broadband spectral modeling that the γ-ray flux of the Fermi-LAT source 2FGLJ1629.4+8236 may well be accounted for by the high-energy tail of the inverse Compton continuum of the lobe. Thus, this claimed association of γ-rays from the NW lobe of NGC6251, together with the recent Fermi-LAT imaging of the extended lobes of CentaurusA, indicates that particles may be efficiently (re-)accelerated up to ultrarelativistic energies within extended radio lobes of nearby radio galaxies in general.

    Original languageEnglish
    Article number66
    JournalAstrophysical Journal
    Volume749
    Issue number1
    DOIs
    Publication statusPublished - 2012 Apr 10

    Fingerprint

    radio galaxies
    lobes
    radio
    x rays
    rays
    telescopes
    imaging spectrometers
    photons
    field of view
    contaminants
    energy
    power law
    spectrometer
    continuums
    broadband
    microwaves
    electron
    nuclei
    pollutant
    modeling

    Keywords

    • acceleration of particles
    • galaxies: individual (NGC 6251)
    • galaxies: jets
    • gamma rays: general
    • radiation mechanisms: non-thermal
    • X-rays: galaxies

    ASJC Scopus subject areas

    • Space and Planetary Science
    • Astronomy and Astrophysics

    Cite this

    Suzaku X-ray imaging of the extended lobe in the giant radio galaxy NGC6251 associated with the fermi-lat source 2FGLJ1629.4+8236. / Takeuchi, Y.; Kataoka, Jun; Stawarz; Takahashi, Y.; Maeda, Keiichi; Nakamori, T.; Cheung, C. C.; Celotti, A.; Tanaka, Y.; Takahashi, T.

    In: Astrophysical Journal, Vol. 749, No. 1, 66, 10.04.2012.

    Research output: Contribution to journalArticle

    Takeuchi, Y. ; Kataoka, Jun ; Stawarz ; Takahashi, Y. ; Maeda, Keiichi ; Nakamori, T. ; Cheung, C. C. ; Celotti, A. ; Tanaka, Y. ; Takahashi, T. / Suzaku X-ray imaging of the extended lobe in the giant radio galaxy NGC6251 associated with the fermi-lat source 2FGLJ1629.4+8236. In: Astrophysical Journal. 2012 ; Vol. 749, No. 1.
    @article{ed085ee5d9d243ffbe7490a66351d543,
    title = "Suzaku X-ray imaging of the extended lobe in the giant radio galaxy NGC6251 associated with the fermi-lat source 2FGLJ1629.4+8236",
    abstract = "We report the results of a Suzaku X-ray imaging study of NGC6251, a nearby giant radio galaxy with intermediate FRI/II radio properties. Our pointing direction was centered on the γ-ray emission peak recently discovered with the Fermi Large Area Telescope (LAT) around the position of the northwest (NW) radio lobe 15 arcmin offset from the nucleus. After subtracting two {"}off-source{"} pointings adjacent to the radio lobe and removing possible contaminants in the X-ray Imaging Spectrometer field of view, we found significant residual X-ray emission most likely diffuse in nature. The spectrum of the excess X-ray emission is well fitted by a power law with a photon index Γ = 1.90 ± 0.15 and a 0.5-8keV flux of 4 × 10 -13ergcm-2s-1. We interpret this diffuse X-ray emission component as being due to inverse Compton upscattering of the cosmic microwave background photons by ultrarelativistic electrons within the lobe, with only a minor contribution from the beamed emission of the large-scale jet. Utilizing archival radio data for the source, we demonstrate by means of broadband spectral modeling that the γ-ray flux of the Fermi-LAT source 2FGLJ1629.4+8236 may well be accounted for by the high-energy tail of the inverse Compton continuum of the lobe. Thus, this claimed association of γ-rays from the NW lobe of NGC6251, together with the recent Fermi-LAT imaging of the extended lobes of CentaurusA, indicates that particles may be efficiently (re-)accelerated up to ultrarelativistic energies within extended radio lobes of nearby radio galaxies in general.",
    keywords = "acceleration of particles, galaxies: individual (NGC 6251), galaxies: jets, gamma rays: general, radiation mechanisms: non-thermal, X-rays: galaxies",
    author = "Y. Takeuchi and Jun Kataoka and Stawarz and Y. Takahashi and Keiichi Maeda and T. Nakamori and Cheung, {C. C.} and A. Celotti and Y. Tanaka and T. Takahashi",
    year = "2012",
    month = "4",
    day = "10",
    doi = "10.1088/0004-637X/749/1/66",
    language = "English",
    volume = "749",
    journal = "Astrophysical Journal",
    issn = "0004-637X",
    publisher = "IOP Publishing Ltd.",
    number = "1",

    }

    TY - JOUR

    T1 - Suzaku X-ray imaging of the extended lobe in the giant radio galaxy NGC6251 associated with the fermi-lat source 2FGLJ1629.4+8236

    AU - Takeuchi, Y.

    AU - Kataoka, Jun

    AU - Stawarz,

    AU - Takahashi, Y.

    AU - Maeda, Keiichi

    AU - Nakamori, T.

    AU - Cheung, C. C.

    AU - Celotti, A.

    AU - Tanaka, Y.

    AU - Takahashi, T.

    PY - 2012/4/10

    Y1 - 2012/4/10

    N2 - We report the results of a Suzaku X-ray imaging study of NGC6251, a nearby giant radio galaxy with intermediate FRI/II radio properties. Our pointing direction was centered on the γ-ray emission peak recently discovered with the Fermi Large Area Telescope (LAT) around the position of the northwest (NW) radio lobe 15 arcmin offset from the nucleus. After subtracting two "off-source" pointings adjacent to the radio lobe and removing possible contaminants in the X-ray Imaging Spectrometer field of view, we found significant residual X-ray emission most likely diffuse in nature. The spectrum of the excess X-ray emission is well fitted by a power law with a photon index Γ = 1.90 ± 0.15 and a 0.5-8keV flux of 4 × 10 -13ergcm-2s-1. We interpret this diffuse X-ray emission component as being due to inverse Compton upscattering of the cosmic microwave background photons by ultrarelativistic electrons within the lobe, with only a minor contribution from the beamed emission of the large-scale jet. Utilizing archival radio data for the source, we demonstrate by means of broadband spectral modeling that the γ-ray flux of the Fermi-LAT source 2FGLJ1629.4+8236 may well be accounted for by the high-energy tail of the inverse Compton continuum of the lobe. Thus, this claimed association of γ-rays from the NW lobe of NGC6251, together with the recent Fermi-LAT imaging of the extended lobes of CentaurusA, indicates that particles may be efficiently (re-)accelerated up to ultrarelativistic energies within extended radio lobes of nearby radio galaxies in general.

    AB - We report the results of a Suzaku X-ray imaging study of NGC6251, a nearby giant radio galaxy with intermediate FRI/II radio properties. Our pointing direction was centered on the γ-ray emission peak recently discovered with the Fermi Large Area Telescope (LAT) around the position of the northwest (NW) radio lobe 15 arcmin offset from the nucleus. After subtracting two "off-source" pointings adjacent to the radio lobe and removing possible contaminants in the X-ray Imaging Spectrometer field of view, we found significant residual X-ray emission most likely diffuse in nature. The spectrum of the excess X-ray emission is well fitted by a power law with a photon index Γ = 1.90 ± 0.15 and a 0.5-8keV flux of 4 × 10 -13ergcm-2s-1. We interpret this diffuse X-ray emission component as being due to inverse Compton upscattering of the cosmic microwave background photons by ultrarelativistic electrons within the lobe, with only a minor contribution from the beamed emission of the large-scale jet. Utilizing archival radio data for the source, we demonstrate by means of broadband spectral modeling that the γ-ray flux of the Fermi-LAT source 2FGLJ1629.4+8236 may well be accounted for by the high-energy tail of the inverse Compton continuum of the lobe. Thus, this claimed association of γ-rays from the NW lobe of NGC6251, together with the recent Fermi-LAT imaging of the extended lobes of CentaurusA, indicates that particles may be efficiently (re-)accelerated up to ultrarelativistic energies within extended radio lobes of nearby radio galaxies in general.

    KW - acceleration of particles

    KW - galaxies: individual (NGC 6251)

    KW - galaxies: jets

    KW - gamma rays: general

    KW - radiation mechanisms: non-thermal

    KW - X-rays: galaxies

    UR - http://www.scopus.com/inward/record.url?scp=84859121054&partnerID=8YFLogxK

    UR - http://www.scopus.com/inward/citedby.url?scp=84859121054&partnerID=8YFLogxK

    U2 - 10.1088/0004-637X/749/1/66

    DO - 10.1088/0004-637X/749/1/66

    M3 - Article

    AN - SCOPUS:84859121054

    VL - 749

    JO - Astrophysical Journal

    JF - Astrophysical Journal

    SN - 0004-637X

    IS - 1

    M1 - 66

    ER -