The linear polarization of 3C 345 in the ultraviolet

Joseph F. Dolan, Patricia T. Boyd, Karen G. Wolinski, Paul S. Smith, Christopher D Impey, Robert C. Bless, M. J. Nelson, J. W. Percival, M. J. Taylor, J. L. Elliot, Edward L. Robinson, G. W. Van Citters

Research output: Contribution to journalArticle

9 Citations (Scopus)

Abstract

The linear polarization of 3C 345, a superluminal radio source and OVV quasar, was observed in two bandpasses in the ultraviolet (centered at 2160 Å and 2770 Å) in 1993 April using the High Speed Photometer on the Hubble Space Telescope. The quasar is significantly polarized in the UV (p > 5%). Ground-based polarimetry was obtained 11 days later, but a difference in the position angle between the observations in the visible and those in the UV indicate that the magnitude of the polarization of 3C 345 may have changed over that time. If the two observation sets represent the same state of spectral polarization, then the large UV flux implies that either the polarization of the synchrotron continuum must stop decreasing in the UV, or that there is an additional source of polarized flux in the ultraviolet. Only if the UV observations represent a spectral polarization state with the same position angle in the visible seen previously in 3C 345 can the polarized flux be represented by a single power law consistent with the three-component model of Smith et al. (1986, 1988). This model consists of a polarized synchrotron component, an unpolarized component from the broad-line region, and an unpolarized component attributed to thermal radiation from an optically thick accretion disk. Additional simultaneous polarimetry in the UV and visible will be required to further constrain models of the continuum emission processes in 3C 345 and determine if the UV polarized flux is synchrotron in origin.

Original languageEnglish (US)
Pages (from-to)560-566
Number of pages7
JournalAstrophysical Journal
Volume432
Issue number2
StatePublished - Sep 10 1994

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linear polarization
polarization
synchrotrons
polarimetry
quasars
continuums
thermal radiation
Hubble Space Telescope
accretion disks
photometers
photometer
high speed
power law
accretion
radio

Keywords

  • Polarization
  • Quasars: individual (3C 345)
  • Ultraviolet: galaxies

ASJC Scopus subject areas

  • Space and Planetary Science

Cite this

Dolan, J. F., Boyd, P. T., Wolinski, K. G., Smith, P. S., Impey, C. D., Bless, R. C., ... Van Citters, G. W. (1994). The linear polarization of 3C 345 in the ultraviolet. Astrophysical Journal, 432(2), 560-566.

The linear polarization of 3C 345 in the ultraviolet. / Dolan, Joseph F.; Boyd, Patricia T.; Wolinski, Karen G.; Smith, Paul S.; Impey, Christopher D; Bless, Robert C.; Nelson, M. J.; Percival, J. W.; Taylor, M. J.; Elliot, J. L.; Robinson, Edward L.; Van Citters, G. W.

In: Astrophysical Journal, Vol. 432, No. 2, 10.09.1994, p. 560-566.

Research output: Contribution to journalArticle

Dolan, JF, Boyd, PT, Wolinski, KG, Smith, PS, Impey, CD, Bless, RC, Nelson, MJ, Percival, JW, Taylor, MJ, Elliot, JL, Robinson, EL & Van Citters, GW 1994, 'The linear polarization of 3C 345 in the ultraviolet', Astrophysical Journal, vol. 432, no. 2, pp. 560-566.
Dolan JF, Boyd PT, Wolinski KG, Smith PS, Impey CD, Bless RC et al. The linear polarization of 3C 345 in the ultraviolet. Astrophysical Journal. 1994 Sep 10;432(2):560-566.
Dolan, Joseph F. ; Boyd, Patricia T. ; Wolinski, Karen G. ; Smith, Paul S. ; Impey, Christopher D ; Bless, Robert C. ; Nelson, M. J. ; Percival, J. W. ; Taylor, M. J. ; Elliot, J. L. ; Robinson, Edward L. ; Van Citters, G. W. / The linear polarization of 3C 345 in the ultraviolet. In: Astrophysical Journal. 1994 ; Vol. 432, No. 2. pp. 560-566.
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abstract = "The linear polarization of 3C 345, a superluminal radio source and OVV quasar, was observed in two bandpasses in the ultraviolet (centered at 2160 {\AA} and 2770 {\AA}) in 1993 April using the High Speed Photometer on the Hubble Space Telescope. The quasar is significantly polarized in the UV (p > 5{\%}). Ground-based polarimetry was obtained 11 days later, but a difference in the position angle between the observations in the visible and those in the UV indicate that the magnitude of the polarization of 3C 345 may have changed over that time. If the two observation sets represent the same state of spectral polarization, then the large UV flux implies that either the polarization of the synchrotron continuum must stop decreasing in the UV, or that there is an additional source of polarized flux in the ultraviolet. Only if the UV observations represent a spectral polarization state with the same position angle in the visible seen previously in 3C 345 can the polarized flux be represented by a single power law consistent with the three-component model of Smith et al. (1986, 1988). This model consists of a polarized synchrotron component, an unpolarized component from the broad-line region, and an unpolarized component attributed to thermal radiation from an optically thick accretion disk. Additional simultaneous polarimetry in the UV and visible will be required to further constrain models of the continuum emission processes in 3C 345 and determine if the UV polarized flux is synchrotron in origin.",
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AU - Bless, Robert C.

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AU - Percival, J. W.

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AB - The linear polarization of 3C 345, a superluminal radio source and OVV quasar, was observed in two bandpasses in the ultraviolet (centered at 2160 Å and 2770 Å) in 1993 April using the High Speed Photometer on the Hubble Space Telescope. The quasar is significantly polarized in the UV (p > 5%). Ground-based polarimetry was obtained 11 days later, but a difference in the position angle between the observations in the visible and those in the UV indicate that the magnitude of the polarization of 3C 345 may have changed over that time. If the two observation sets represent the same state of spectral polarization, then the large UV flux implies that either the polarization of the synchrotron continuum must stop decreasing in the UV, or that there is an additional source of polarized flux in the ultraviolet. Only if the UV observations represent a spectral polarization state with the same position angle in the visible seen previously in 3C 345 can the polarized flux be represented by a single power law consistent with the three-component model of Smith et al. (1986, 1988). This model consists of a polarized synchrotron component, an unpolarized component from the broad-line region, and an unpolarized component attributed to thermal radiation from an optically thick accretion disk. Additional simultaneous polarimetry in the UV and visible will be required to further constrain models of the continuum emission processes in 3C 345 and determine if the UV polarized flux is synchrotron in origin.

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