Skip to main content Accessibility help
×
Home

High Optical Polarization in Flat-Spectrum Radio Sources

  • D. Wills (a1), Beverley J. Wills (a1), R.R.J. Antonucci (a2), Richard Barvainis (a3), Michel Breger (a4), J. A. Bailey (a5), J. H. Hough (a6) and K. Ballard (a7)...

Extract

We have made a polarimetric survey of 84 quasi-stellar objects, to supplement published polarization measurements for two samples of quasars identified with flat-spectrum (core-dominant) radio sources in 5 GHz surveys made at Bonn (Kühr 1980) and at the VLA (Perley 1982). The observations were made using the McDonald 2.1m Struve reflector and the polarimeter described by Breger (1979); the typical accuracy is 0.5% for an 18 mag object after half an hour. Earlier surveys, such as those by Stockman, Moore and Angel (1984), included objects of various radio spectral types, and only a small fraction of the objects showed high polarization (> 3%), but our sample of flat-spectrum quasars reveals many more (about half) of the objects to be highly polarized. Some of them are, expectedly, of the BL Lac class, but many of them have strong broad emission lines. There are two striking correlations among the results:

  1. (1)The degree of polarization is strongly correlated with the dominance of the radio core - specifically, with the ratio, R, of core to lobe luminosity (Fig. 1). For example, about 75% of the objects with log R > 1.25 and redshift z < 1 have p > 3%. This relation implies that if the radio core radiation is beamed, as seems likely, then so is the optical synchrotron component.
  2. (2)The fraction of objects with p > 3% is inversely correlated with redshift (e.g. Fig. 2). The most likely interpretation of this result is that quasars' degree of polarization decreases with decreasing rest wavelength, and the shorter wavelengths are shifted into our wide observational passband at higher redshifts.

    • Send article to Kindle

      To send this article to your Kindle, first ensure no-reply@cambridge.org is added to your Approved Personal Document E-mail List under your Personal Document Settings on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part of your Kindle email address below. Find out more about sending to your Kindle. Find out more about sending to your Kindle.

      Note you can select to send to either the @free.kindle.com or @kindle.com variations. ‘@free.kindle.com’ emails are free but can only be sent to your device when it is connected to wi-fi. ‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.

      Find out more about the Kindle Personal Document Service.

      High Optical Polarization in Flat-Spectrum Radio Sources
      Available formats
      ×

      Send article to Dropbox

      To send this article to your Dropbox account, please select one or more formats and confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your <service> account. Find out more about sending content to Dropbox.

      High Optical Polarization in Flat-Spectrum Radio Sources
      Available formats
      ×

      Send article to Google Drive

      To send this article to your Google Drive account, please select one or more formats and confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your <service> account. Find out more about sending content to Google Drive.

      High Optical Polarization in Flat-Spectrum Radio Sources
      Available formats
      ×

Copyright

References

Hide All
Breger, M. 1979, Ap.J. 233, 97.
Bailey, J.A. and Hough, J. H. 1982, PASP 94, 618.
Kühr, H. 1980, (Bonn).
Perley, R.A. 1982, A.J. 87, 859.
Smith, P.S. et al. 1988, Ap.J. Letts. 326, L39.
Stockman, H.S., Moore, R.L. and Angel, J.R.P. 1984, Ap.J. 279, 485.

High Optical Polarization in Flat-Spectrum Radio Sources

  • D. Wills (a1), Beverley J. Wills (a1), R.R.J. Antonucci (a2), Richard Barvainis (a3), Michel Breger (a4), J. A. Bailey (a5), J. H. Hough (a6) and K. Ballard (a7)...

Metrics

Full text views

Total number of HTML views: 0
Total number of PDF views: 0 *
Loading metrics...

Abstract views

Total abstract views: 0 *
Loading metrics...

* Views captured on Cambridge Core between <date>. This data will be updated every 24 hours.

Usage data cannot currently be displayed