## Very close pairs of quasi-stellar objects
^{1} Center for Astrophysics and Space Sciences and Department
of Physics, University of California, La Jolla, California 92093-0111,
USA^{2} 102 Admirals Walk, Bournemouth BH2 5HF Dorset, UK^{3} Max Planck Institut für Astrophysik,
Karl-Schwarzschild-Strasse 1, D-85740 Garching bei München,
Germany
It is pointed out that there are now known four very close pairs of QSOs with separations arcsec and very different redshifts. Several estimates indicates that the probability that they are accidental configurations are small; a conservative estimate of the probability to have four such pairs by random projection yields . We conclude either that this is further evidence that QSOs have significant non-cosmological redshift components, or that the pairs must be explained by gravitational lensing.
## Contents- 1. Introduction
- 2. The observational data and probability calculations
- 3. Possible interpretations
- 4. A gravitational lens origin for close QSO pairs
- 5. Conclusion
- Acknowledgements
- References
© European Southern Observatory (ESO) 1997 Online publication: July 3, 1998 |