SIMBAD references

Two new samples of QSOs have been constructed from recent surveys to test the hypothesis that the redshift distribution of bright QSOs is periodic in log(1+z). The first of these comprises 57 different redshifts among all known close pairs or multiple QSOs with image separations ≤10", and the second consists of 39 QSOs selected through their X-ray emission and their proximity to bright, comparatively nearby active galaxies. The redshift distributions of the samples are found to exhibit distinct peaks with a periodic separation of ∼0.089 in log(1+z) identical to that claimed in earlier samples, but now extended out to higher redshift peaks z=2.63, 3.45, and 4.47, predicted by the formula but never seen before. The periodicity is also seen in a third sample, the 78 QSOs of the 3C and 3CR catalogs. It is present in these three data sets at a high overall significance level (∼10^–5) and appears not to be explicable by spectroscopic or similar selection effects. Possible interpretations are briefly discussed.