Reference : Close pairs of quasars with different redshifts: New observations and results
Scientific journals : Article
Physical, chemical, mathematical & earth Sciences : Space science, astronomy & astrophysics
http://hdl.handle.net/2268/176226
Close pairs of quasars with different redshifts: New observations and results
English
Sluse, Dominique mailto [Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Astroph. extragalactique et observations spatiales (AEOS) >]
Surdej, Jean [Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Astroph. extragalactique et observations spatiales (AEOS) >]
Claeskens, Jean-François [Institut d'Astrophysique et de Géophysique, Université de Liège, Allée du 6 Août, 17, B5C, 4000 Sart Tilman, Belgium]
De Rop, Yves [Université de Liège - ULiège > Département de physique > Imagerie médicale expérimentale >]
Lee, D. W. [Institut d'Astrophysique et de Géophysique, Université de Liège, Allée du 6 Août, 17, B5C, 4000 Sart Tilman, Belgium]
Iovino, A. [Osservatorio Astronomico di Brera, Via Brera 28, 20121 Milano, Italy]
Hawkins, M. R. S. [Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ, Scotland, UK)]
1-Jan-2003
Astronomy and Astrophysics
397
539-544
Yes
International
[en] quasars: general ; gravitational lensing
[en] Burbidge et al. (\cite {burbidge}) argue that the observed number of quasar pairs with small angular separations and different redshifts (typically Delta theta <= 5 arcsec and Delta z > 0.1 ) is not compatible with a random distribution of quasars over the sky. After a brief review of all known quasar pairs with different redshifts, we show by means of very simple calculations that the probability of finding the three accepted pairs accidentally is of the order of 10%. We conclude that, under realistic hypotheses, the observed number of quasar pairs with different redshifts is not unlikely. We also present arguments showing that gravitational lensing biases are probably not strong enough to significantly increase the expected number of quasar pairs. The failure to detect with HST a secondary lensed image of the background quasar near the foreground one in these three pairs supports this view.
http://hdl.handle.net/2268/176226
10.1051/0004-6361:20021524
http://adsabs.harvard.edu/abs/2003A%26A...397..539S

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