Polarimetric and spectroscopic optical observations of the ultra-compact X-ray binary 4U 0614+091

M. C. Baglio, D. Mainetti, P. D'Avanzo, S. Campana, S. Covino, Dave Russell, T. Shahbaz

    Research output: Contribution to journalArticle

    Abstract

    Aims. We present a polarimetric and spectroscopic study of the persistent ultra-compact X-ray binary 4U 0614+091 aimed at searching for the emission of a relativistic particle jet and at unveiling the orbital period Porb of the system. Methods. We obtained r-band polarimetric observations with the Telescopio Nazionale Galileo (TNG) equipped with the PAOLO polarimeter and with the Nordic Optical Telescope (NOT) equipped with the ALFOSC instrument, covering ~2 h and ~0.5 h observations, respectively. We carried out low resolution spectroscopy of the system using the ESO Very Large Telescope equipped with FORS1 for ~1.5 h (16 spectra covering the range 4300-8000 Å). Results. The polarimetric analysis performed starting from the TNG dataset revealed a polarisation degree in the r-band of 3% ± 1%. From the NOT dataset, due to the lower signal-to-noise ratio, we could obtain only a 3σ upper limit of 3.4%. From the joining of a spectroscopic and photometric analysis, through the study of the equivalent width variations of the CII 7240 Å line and the r-band light curve, we could find a hint of a ~45 min periodicity. Conclusions. A polarisation degree P of ~3% in the r-band is consistent with the emission of a relativistic particle jet, which is supposed to emit intrinsically linearly polarised synchrotron radiation. Since no variations of P with time have been detected, and the accretion disc of the system does not contain ionised hydrogen, scattering by free electrons in the accretion disc has been rejected. The period of ~45 min obtained through the analysis of the system light curve and of the equivalent width variations of the selected spectral line is probably linked to the presence of a hot spot or a superhump in the accretion disc, and lead to an orbital period ? 1 h for the binary system.

    Original languageEnglish (US)
    Article numberA99
    JournalAstronomy and Astrophysics
    Volume572
    DOIs
    StatePublished - Dec 1 2014

    Fingerprint

    accretion
    accretion disks
    relativistic particles
    telescopes
    polarization
    light curve
    coverings
    x rays
    orbitals
    signal-to-noise ratio
    periodicity
    hot spot
    spectroscopic analysis
    polarimeters
    European Southern Observatory
    spectroscopy
    scattering
    hydrogen
    free electrons
    line spectra

    Keywords

    • Polarisation
    • Stars: jets
    • Stars: neutron
    • X-rays: binaries

    ASJC Scopus subject areas

    • Astronomy and Astrophysics
    • Space and Planetary Science

    Cite this

    Baglio, M. C., Mainetti, D., D'Avanzo, P., Campana, S., Covino, S., Russell, D., & Shahbaz, T. (2014). Polarimetric and spectroscopic optical observations of the ultra-compact X-ray binary 4U 0614+091. Astronomy and Astrophysics, 572, [A99]. https://doi.org/10.1051/0004-6361/201424665

    Polarimetric and spectroscopic optical observations of the ultra-compact X-ray binary 4U 0614+091. / Baglio, M. C.; Mainetti, D.; D'Avanzo, P.; Campana, S.; Covino, S.; Russell, Dave; Shahbaz, T.

    In: Astronomy and Astrophysics, Vol. 572, A99, 01.12.2014.

    Research output: Contribution to journalArticle

    Baglio, MC, Mainetti, D, D'Avanzo, P, Campana, S, Covino, S, Russell, D & Shahbaz, T 2014, 'Polarimetric and spectroscopic optical observations of the ultra-compact X-ray binary 4U 0614+091', Astronomy and Astrophysics, vol. 572, A99. https://doi.org/10.1051/0004-6361/201424665
    Baglio, M. C. ; Mainetti, D. ; D'Avanzo, P. ; Campana, S. ; Covino, S. ; Russell, Dave ; Shahbaz, T. / Polarimetric and spectroscopic optical observations of the ultra-compact X-ray binary 4U 0614+091. In: Astronomy and Astrophysics. 2014 ; Vol. 572.
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    abstract = "Aims. We present a polarimetric and spectroscopic study of the persistent ultra-compact X-ray binary 4U 0614+091 aimed at searching for the emission of a relativistic particle jet and at unveiling the orbital period Porb of the system. Methods. We obtained r-band polarimetric observations with the Telescopio Nazionale Galileo (TNG) equipped with the PAOLO polarimeter and with the Nordic Optical Telescope (NOT) equipped with the ALFOSC instrument, covering ~2 h and ~0.5 h observations, respectively. We carried out low resolution spectroscopy of the system using the ESO Very Large Telescope equipped with FORS1 for ~1.5 h (16 spectra covering the range 4300-8000 {\AA}). Results. The polarimetric analysis performed starting from the TNG dataset revealed a polarisation degree in the r-band of 3{\%} ± 1{\%}. From the NOT dataset, due to the lower signal-to-noise ratio, we could obtain only a 3σ upper limit of 3.4{\%}. From the joining of a spectroscopic and photometric analysis, through the study of the equivalent width variations of the CII 7240 {\AA} line and the r-band light curve, we could find a hint of a ~45 min periodicity. Conclusions. A polarisation degree P of ~3{\%} in the r-band is consistent with the emission of a relativistic particle jet, which is supposed to emit intrinsically linearly polarised synchrotron radiation. Since no variations of P with time have been detected, and the accretion disc of the system does not contain ionised hydrogen, scattering by free electrons in the accretion disc has been rejected. The period of ~45 min obtained through the analysis of the system light curve and of the equivalent width variations of the selected spectral line is probably linked to the presence of a hot spot or a superhump in the accretion disc, and lead to an orbital period ? 1 h for the binary system.",
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    AU - Baglio, M. C.

    AU - Mainetti, D.

    AU - D'Avanzo, P.

    AU - Campana, S.

    AU - Covino, S.

    AU - Russell, Dave

    AU - Shahbaz, T.

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    N2 - Aims. We present a polarimetric and spectroscopic study of the persistent ultra-compact X-ray binary 4U 0614+091 aimed at searching for the emission of a relativistic particle jet and at unveiling the orbital period Porb of the system. Methods. We obtained r-band polarimetric observations with the Telescopio Nazionale Galileo (TNG) equipped with the PAOLO polarimeter and with the Nordic Optical Telescope (NOT) equipped with the ALFOSC instrument, covering ~2 h and ~0.5 h observations, respectively. We carried out low resolution spectroscopy of the system using the ESO Very Large Telescope equipped with FORS1 for ~1.5 h (16 spectra covering the range 4300-8000 Å). Results. The polarimetric analysis performed starting from the TNG dataset revealed a polarisation degree in the r-band of 3% ± 1%. From the NOT dataset, due to the lower signal-to-noise ratio, we could obtain only a 3σ upper limit of 3.4%. From the joining of a spectroscopic and photometric analysis, through the study of the equivalent width variations of the CII 7240 Å line and the r-band light curve, we could find a hint of a ~45 min periodicity. Conclusions. A polarisation degree P of ~3% in the r-band is consistent with the emission of a relativistic particle jet, which is supposed to emit intrinsically linearly polarised synchrotron radiation. Since no variations of P with time have been detected, and the accretion disc of the system does not contain ionised hydrogen, scattering by free electrons in the accretion disc has been rejected. The period of ~45 min obtained through the analysis of the system light curve and of the equivalent width variations of the selected spectral line is probably linked to the presence of a hot spot or a superhump in the accretion disc, and lead to an orbital period ? 1 h for the binary system.

    AB - Aims. We present a polarimetric and spectroscopic study of the persistent ultra-compact X-ray binary 4U 0614+091 aimed at searching for the emission of a relativistic particle jet and at unveiling the orbital period Porb of the system. Methods. We obtained r-band polarimetric observations with the Telescopio Nazionale Galileo (TNG) equipped with the PAOLO polarimeter and with the Nordic Optical Telescope (NOT) equipped with the ALFOSC instrument, covering ~2 h and ~0.5 h observations, respectively. We carried out low resolution spectroscopy of the system using the ESO Very Large Telescope equipped with FORS1 for ~1.5 h (16 spectra covering the range 4300-8000 Å). Results. The polarimetric analysis performed starting from the TNG dataset revealed a polarisation degree in the r-band of 3% ± 1%. From the NOT dataset, due to the lower signal-to-noise ratio, we could obtain only a 3σ upper limit of 3.4%. From the joining of a spectroscopic and photometric analysis, through the study of the equivalent width variations of the CII 7240 Å line and the r-band light curve, we could find a hint of a ~45 min periodicity. Conclusions. A polarisation degree P of ~3% in the r-band is consistent with the emission of a relativistic particle jet, which is supposed to emit intrinsically linearly polarised synchrotron radiation. Since no variations of P with time have been detected, and the accretion disc of the system does not contain ionised hydrogen, scattering by free electrons in the accretion disc has been rejected. The period of ~45 min obtained through the analysis of the system light curve and of the equivalent width variations of the selected spectral line is probably linked to the presence of a hot spot or a superhump in the accretion disc, and lead to an orbital period ? 1 h for the binary system.

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    KW - Stars: jets

    KW - Stars: neutron

    KW - X-rays: binaries

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