Advertisement

OH maser polarization

  • Shuji Deguchi
  • William D. Watson
2. Theory
Part of the Lecture Notes in Physics book series (LNP, volume 412)

Abstract

The mechanism to produce circular polarization has been reinvestigated under conditions with radiative pumping and the Faraday rotation due to electrons. A new radiative pump mechanism is proposed for the OH main line masers. A parity propensity for the OH collisional excitation, which has recently been found by laboratory experiments, prohibits the collisional pumping of the main line masers. It is shown that the inversion can be created when the radiation temperature is higher than the kinetic temperature. The anisotropic radiative pump can produce unequal magnetic sublevel populations. In addition to the line overlap between the Zeeman triplet of the OH main lines, a modest amount of the Faraday rotation due to electrons can increase the degree of circular polarization of OH masers even when the angle to the magnetic filed is near π/2.

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. Andresen, P., Hausier, D., & Lulf, H. W., 1984, J. Chem. Phys. 81, 571Google Scholar
  2. Andresen, P., Aristov, N., Beushausen, V., Hausier D., & Lulf, H. W., 1991, J. Chem. Phys. 95, 5773Google Scholar
  3. Cesaroni, & Walmsley, 1991, AAp. 241, 537Google Scholar
  4. Cohen, R. J., Downes, G, Emerson, R., Grimm, M., Guikis, S., Stevens, G., & Tarter, J., 1987, MNRAS. 225, 491Google Scholar
  5. Bujarrabal, V., Guilbert, J., Nguyen-Q-Rieu, & Omont, A., 1980, AAp. 84, 311Google Scholar
  6. Cook, A. H. 1966, Nature 221, 503Google Scholar
  7. Deguchi, S., & Watson, W. D., 1985, ApJ. 289, 621Google Scholar
  8. Deguchi, S., & Watson, W. D., 1986, ApJ. 300, L15Google Scholar
  9. Doel, R. C., Gray, M. D., & Field, D., 1990, MNRAS. 244, 504Google Scholar
  10. Dewangan, D. P., Flower, D. R., & Alexander, M. H., 1987, MNRAS. 226, 505Google Scholar
  11. Kylafs, N. D., & Norman, C. A., 1990, ApJ. 350, 209Google Scholar
  12. Nedoluha, G., and Watson, W. D., 1989, ApJ. 335, L20Google Scholar
  13. Reid. M. J., & Moran, J. M., 1981, Ann. Rcv. AAp. 19, 231Google Scholar

Copyright information

© Springer-Verlag 1993

Authors and Affiliations

  • Shuji Deguchi
    • 1
  • William D. Watson
    • 2
  1. 1.Nobeyama Radio ObservatoryNational Astronomical ObservatoryNaganoJapan
  2. 2.Department of PhysicsUniversity of IllinoisUrbana

Personalised recommendations