منابع مشابه
Two Close–Separation Quasar–Quasar Pairs in the Large Bright Quasar Survey
We present photometric and spectroscopic observations of two close quasar– quasar pairs found in the Large Bright Quasar Survey (LBQS) (Hewett et al. 1995, AJ, 109, 1498). The two components of the 2153-2056 pair (z = 1.845, ∆θ = 7. 8, B = 17.9 and 21.3) have the same redshifts within the relatively large uncertainty, ∆vA−B = −1100±1500 km s, of the observations. The quasars are most likely spa...
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We use the Véron-Cetty & Véron (2000) catalog (VV) of 13 213 quasars to investigate their possible physical grouping over angular scales 10′′ ≤ ∆θ ≤ 1000′′. We first estimate the number of quasar pairs that would be expected in VV assuming a random distribution for the quasar positions and taking into account observational selection effects affecting heterogeneous catalogs. We find in VV a stat...
متن کاملWhy Quasar Pairs Are Binary Quasars And Not Gravitational Lenses
We use simple comparisons of the optical and radio properties of the wide separation (3 < < 10) quasar pairs to demonstrate that they are binary quasars rather than gravitational lenses. The most likely model is that all the pairs are binary quasars, with a one-sided 2{ (1{ ) upper limit of 22% (8%) on the lens fraction. Simple models for the expected enhancement of quasar activity during galax...
متن کاملQSO mass constraints from gravitational lensing studies of quasar pairs
New constraints on the mass of quasars are derived from gravitational lensing studies of the QSO pairs Q1548+114 A & B and Q1148+0055 A & B, for which new ground-based and Hubble Space Telescope (HST) direct imagery have been obtained. In the case of Q1548+114 A & B, QSO A has been resolved into its host galaxy and a close companion. The nondetection with HST of a secondary lensed image of the ...
متن کاملTowards Constraints on Dark Energy from Absorption Spectra of Close Quasar Pairs
A comparison between the line of sight power spectrum (the auto spectrum) of absorption in the Lyman-alpha forest and the cross power spectrum (the cross spectrum) between the absorption in neighboring lines of sight offers an evolution-free means to constrain the cosmological constant, or dark energy. Using cosmological simulations, we consider a maximum likelihood method to obtain constraints...
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ژورنال
عنوان ژورنال: Symposium - International Astronomical Union
سال: 1986
ISSN: 0074-1809
DOI: 10.1017/s0074180900153227