천문학회지 (Journal of The Korean Astronomical Society)

  • 제44권2호
  • /
  • Pages.59-65
  • /
  • 2011
  • /
  • 1225-4614(pISSN)
  • /
  • 2288-890X(eISSN)
한국천문학회 (The Korean Astronomical Society)
권호 표지
DOI QR코드

DOI QR Code

LINEAR POLARIZATION OF A DOUBLE PEAKED BROAD EMISSION LINE IN ACTIVE GALACTIC NUCLEI

  • Lee, Hee-Won (Department of Astronomy and Space Science, Sejong University)
  • 투고 : 2011.02.18
  • 심사 : 2011.03.28
  • 발행 : 2011.04.30
PDF 다운로드
⟨ 이전 논문 다음 논문 ⟩

초록

A small number of active galactic nuclei are known to exhibit prominent double peak emission profiles that are well-fitted by a relativistic accretion disk model. We develop a Monte Carlo code to compute the linear polarization of a double peaked broad emission line arising from Thomson scattering. A Keplerian accretion disk is adopted for the double peak emission line region and the geometry is assumed to be Schwarzschild. Far from the accretion disk where flat Minkowski geometry is appropriate, we place an azimuthally symmetric scattering region in the shape of a spherical shell sliced with ${\Delta}{\mu}=0.1$. Adopting a Monte Carlo method we generate line photons in the accretion disk in arbitrary directions in the local rest frame and follow the geodesic paths of the photons until they hit the scattering region. The profile of the polarized flux is mainly determined by the relative location of the scattering region with respect to the emission source. When the scattering region is in the polar direction, the degree of linear polarization also shows a double peak structure. Under favorable conditions we show that up to 0.6% linear polarization may be obtained. We conclude that spectropolarimetry can be a powerful probe to reveal much information regarding the accretion disk geometry of these active galactic nuclei.

키워드

참고문헌

  1. Antonucci, R. R. 1993, Unified Models for Active Galactic Nuclei and Quasars, ARA&A, 31, 473 https://doi.org/10.1146/annurev.aa.31.090193.002353
  2. Antonucci, R. R., & Miller, J. S. 1985, Spectropo-larimetry and the Nature of NGC 1068, ApJ, 297, 621 https://doi.org/10.1086/163559
  3. Arav, N., Barlow, T. A., Laor, A., Sargent, W. L. W., & Blandford, R. D. 1998, MNRAS, 297, 990 https://doi.org/10.1046/j.1365-8711.1998.297004990.x
  4. Blandford, R. D., & McKee, C. F. 1982, Reverberation Mapping of the Emission Line Regions of Seyfert Galaxies and Quasars, ApJ, 255, 419 https://doi.org/10.1086/159843
  5. Chen, K., & Halpern, J. P. 1989, Structure of Line-Emitting Accretion Disks in Active Galactic Nuclei- Arp 102B, ApJ, 344, 115 https://doi.org/10.1086/167782
  6. Chen, K., Halpern, J. P., & Filippenko, A. V. 1989, Kinematic Evidence for a Relativisitc Keplerian Disk: Arp 102B, ApJ, 339, 742 https://doi.org/10.1086/167332
  7. Eracleous, M., & Halpern, J. P. 1994, Doubled-Peaked Emission Lines in Active Galactic Nuclei, ApJS, 90, 1 https://doi.org/10.1086/191856
  8. Eracleous, M., Livio, M., Halpern, J. P., & Storchi-Bergmann, T. 1995, Elliptical Accretion Disks in Active Galactic Nuclei, ApJ, 438, 610 https://doi.org/10.1086/175104
  9. Gaskell, C. M. 1996, Evidence for Binary Orbital Motion of a Quasar Broad-Line Region, ApJ, 464, L107 https://doi.org/10.1086/310119
  10. Koratkar, A., Antonucci, R. R. J., Goodrich, R. W., Bushouse, H., & Kinney, A. L. 1995, Quasar Lyman Edge Regions in Polarized Light, ApJ, 450, 501 https://doi.org/10.1086/176160
  11. Laor, A., Bahcall, J. N., Jannuzi, B. T., Schneider, D. P., Green, R. F., & Hartig, G. F. 1994, The Ultraviolet Emission Properties of Five Low-Redshift ActiveGalactic Nuclei at High Signal-to-Noise Ratio and Spectral Resolution, ApJ, 420, 110 https://doi.org/10.1086/173545
  12. Laor, A. 2006, Evidence of Line Broadening by Electron Scattering in the Broad Line Region of NGC 4395, ApJ, 643, 112 https://doi.org/10.1086/502798
  13. Lee, H.-W., & Ahn, S.-H. 1998, Polarization of the Ly alpha from an Anisotropically Expanding H I Shell in Primeval Galaxies, ApJ, 504, L61 https://doi.org/10.1086/311572
  14. Lee, H.-W., & Blandford, R. D. 1997, On the Polarization of Resonantly Scattered Emission Lines - III. Polarization of Quasar Broad Emission Lines and Broad Absorption Line Troughs, MNRAS, 288, 19 https://doi.org/10.1093/mnras/288.1.19
  15. Misner, C. W., Thorne, K. S., & Wheeler, J. A. 1979, Gravitation, Freeman
  16. Luminet, J. P. 1979, Image of a Spherical Black Hole with Thin Accretion Disk, A&A, 75, 228
  17. Osterbrock, D., & Ferland, G. 2005, Astrophysics of Gaseous Nebulae and Active Galactic Nuclei, University Science Books
  18. Puchnarewicz, E. M., Mason, K. O., & Carrera, F. J. 1996, Double-Peaked Balmer Line Emission in the Radio-Quiet AGN RX J1042+1212, MNRAS, 283,1311 https://doi.org/10.1093/mnras/283.4.1311
  19. Shapiro, S. L., & Teukolsky, S. A. 1986, Black Holes, White Dwarfs and Neutron Stars: The Physics of Compact Objects, Wiley
  20. Zheng, W., Sulentic, J. W., & Binette, L. 1990, A Double-Stream Model for Line Profiles, ApJ, 365, 115 https://doi.org/10.1086/169462