Unraveling the nature of unidentified high galactic latitude FERMI/LAT gamma-ray sources with Suzaku

Keiichi Maeda, Jun Kataoka, T. Nakamori, L. Stawarz, R. Makiya, T. Totani, C. C. Cheung, D. Donato, N. Gehrels, P. Saz Parkinson, Y. Kanai, N. Kawai, Y. Tanaka, R. Sato, T. Takahashi, Y. Takahashi

    Research output: Contribution to journalArticle

    14 Citations (Scopus)

    Abstract

    Here we report on the results of deep X-ray follow-up observations of four unidentified γ-ray sources detected by the Fermi/LAT instrument at high Galactic latitudes using the X-ray Imaging Spectrometers on board the Suzaku satellite. All of the studied objects were detected with high significance during the first three months of Fermi/LAT operation and subsequently better localized in the first Fermi/LAT catalog (1FGL). For some of them, possible associations with pulsars and active galaxies have subsequently been discussed, and our observations provide an important contribution to this debate. In particular, a bright X-ray point source has been found within the 95% confidence error circle of 1FGLJ1231.1-1410. The X-ray spectrum of the discovered Suzaku counterpart of 1FGLJ1231.1-1410 is well fitted by a blackbody with an additional power-law component. This supports the recently claimed identification of this source with a millisecond pulsar PSRJ1231-1411. For the remaining three Fermi objects, on the other hand, the X-ray observations performed are less conclusive. In the case of 1FGLJ1311.7-3429, two bright X-ray point sources were found within the LAT 95% error circle. Even though the X-ray spectral and variability properties for these sources were robustly assessed, their physical nature and relationship with the γ-ray source remain uncertain. Similarly, we found several weak X-ray sources in the field of 1FGLJ1333.2+5056, one coinciding with the high-redshift blazar CLASSJ1333+5057. We argue that the available data are consistent with the physical association between these two objects, although the large positional uncertainty of the γ-ray source hinders a robust identification. Finally, we have detected an X-ray point source in the vicinity of 1FGLJ2017.3+0603. This Fermi object was recently suggested to be associated with a newly discovered millisecond radio pulsar PSRJ2017+0603, because of the spatial coincidence and the detection of the γ-ray pulsations in the light curve of 1FGLJ2017.3+0603. Interestingly, we have detected the X-ray counterpart of the high-redshift blazar CLASSJ2017+0603, located within the error circle of the γ-ray source, while we were only able to determine an X-ray flux upper limit at the pulsar position. All in all, our studies indicate that while a significant fraction of unidentified high Galactic latitude γ-ray sources is related to the pulsar and blazar phenomena, associations with other classes of astrophysical objects are still valid options.

    Original languageEnglish
    Article number103
    JournalAstrophysical Journal
    Volume729
    Issue number2
    DOIs
    Publication statusPublished - 2011 Mar 10

    Fingerprint

    rays
    pulsars
    x rays
    point sources
    point source
    active galaxies
    imaging spectrometers
    light curve
    catalogs
    confidence
    astrophysics
    power law
    spectrometer
    radio
    galaxies

    Keywords

    • galaxies: active
    • gamma rays: general
    • pulsars: general
    • radiation mechanisms: non-thermal
    • X-rays: general

    ASJC Scopus subject areas

    • Space and Planetary Science
    • Astronomy and Astrophysics

    Cite this

    Unraveling the nature of unidentified high galactic latitude FERMI/LAT gamma-ray sources with Suzaku. / Maeda, Keiichi; Kataoka, Jun; Nakamori, T.; Stawarz, L.; Makiya, R.; Totani, T.; Cheung, C. C.; Donato, D.; Gehrels, N.; Saz Parkinson, P.; Kanai, Y.; Kawai, N.; Tanaka, Y.; Sato, R.; Takahashi, T.; Takahashi, Y.

    In: Astrophysical Journal, Vol. 729, No. 2, 103, 10.03.2011.

    Research output: Contribution to journalArticle

    Maeda, K, Kataoka, J, Nakamori, T, Stawarz, L, Makiya, R, Totani, T, Cheung, CC, Donato, D, Gehrels, N, Saz Parkinson, P, Kanai, Y, Kawai, N, Tanaka, Y, Sato, R, Takahashi, T & Takahashi, Y 2011, 'Unraveling the nature of unidentified high galactic latitude FERMI/LAT gamma-ray sources with Suzaku', Astrophysical Journal, vol. 729, no. 2, 103. https://doi.org/10.1088/0004-637X/729/2/103
    Maeda, Keiichi ; Kataoka, Jun ; Nakamori, T. ; Stawarz, L. ; Makiya, R. ; Totani, T. ; Cheung, C. C. ; Donato, D. ; Gehrels, N. ; Saz Parkinson, P. ; Kanai, Y. ; Kawai, N. ; Tanaka, Y. ; Sato, R. ; Takahashi, T. ; Takahashi, Y. / Unraveling the nature of unidentified high galactic latitude FERMI/LAT gamma-ray sources with Suzaku. In: Astrophysical Journal. 2011 ; Vol. 729, No. 2.
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    AU - Kataoka, Jun

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    AU - Stawarz, L.

    AU - Makiya, R.

    AU - Totani, T.

    AU - Cheung, C. C.

    AU - Donato, D.

    AU - Gehrels, N.

    AU - Saz Parkinson, P.

    AU - Kanai, Y.

    AU - Kawai, N.

    AU - Tanaka, Y.

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    N2 - Here we report on the results of deep X-ray follow-up observations of four unidentified γ-ray sources detected by the Fermi/LAT instrument at high Galactic latitudes using the X-ray Imaging Spectrometers on board the Suzaku satellite. All of the studied objects were detected with high significance during the first three months of Fermi/LAT operation and subsequently better localized in the first Fermi/LAT catalog (1FGL). For some of them, possible associations with pulsars and active galaxies have subsequently been discussed, and our observations provide an important contribution to this debate. In particular, a bright X-ray point source has been found within the 95% confidence error circle of 1FGLJ1231.1-1410. The X-ray spectrum of the discovered Suzaku counterpart of 1FGLJ1231.1-1410 is well fitted by a blackbody with an additional power-law component. This supports the recently claimed identification of this source with a millisecond pulsar PSRJ1231-1411. For the remaining three Fermi objects, on the other hand, the X-ray observations performed are less conclusive. In the case of 1FGLJ1311.7-3429, two bright X-ray point sources were found within the LAT 95% error circle. Even though the X-ray spectral and variability properties for these sources were robustly assessed, their physical nature and relationship with the γ-ray source remain uncertain. Similarly, we found several weak X-ray sources in the field of 1FGLJ1333.2+5056, one coinciding with the high-redshift blazar CLASSJ1333+5057. We argue that the available data are consistent with the physical association between these two objects, although the large positional uncertainty of the γ-ray source hinders a robust identification. Finally, we have detected an X-ray point source in the vicinity of 1FGLJ2017.3+0603. This Fermi object was recently suggested to be associated with a newly discovered millisecond radio pulsar PSRJ2017+0603, because of the spatial coincidence and the detection of the γ-ray pulsations in the light curve of 1FGLJ2017.3+0603. Interestingly, we have detected the X-ray counterpart of the high-redshift blazar CLASSJ2017+0603, located within the error circle of the γ-ray source, while we were only able to determine an X-ray flux upper limit at the pulsar position. All in all, our studies indicate that while a significant fraction of unidentified high Galactic latitude γ-ray sources is related to the pulsar and blazar phenomena, associations with other classes of astrophysical objects are still valid options.

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