منابع مشابه
Binary quasars
Quasar pairs are either physically distinct binary quasars or the result of gravitational lensing. The majority of known pairs are in fact lenses, with a few confirmed as binaries, leaving a population of objects that have not yet been successfully classified. Building on the arguments of Kochanek, Falco & Muñoz (1999a), it is shown that there are no objective reasons to reject the binary inter...
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 کاملDo Quasars Lens Quasars?
If the unexpectedly high frequency of quasar pairs with very different component redshifts is due to the lensing of a population of background quasars by the foreground quasar, typical lens masses must be ∼ 10M⊙ and the sum of all such quasar lenses would have to contain ∼ 0.005 times the closure density of the Universe. It then seems plausible that a very high fraction of all ∼ 10M⊙ gravitatio...
متن کاملQuasars Probing Quasars I: Optically Thick Absorbers near Luminous Quasars
With close pairs of quasars at different redshifts, a background quasar sightline can be used to study a foreground quasar’s environment in absorption. We search 149 moderate resolution background quasar spectra, from Gemini, Keck, the MMT, and the SDSS to survey Lyman Limit Systems (LLSs) and Damped Lyα systems (DLAs) in the vicinity of 1.8 < z < 4.0 luminous foreground quasars. A sample of 27...
متن کاملA Population of Short-Period Variable Quasars from PTF as Supermassive Black Hole Binary Candidates
Supermassive black hole binaries (SMBHBs) at sub-parsec separations should be common in galactic nuclei, as a result of frequent galaxy mergers. Hydrodynamical simulations of circumbinary discs predict strong periodic modulation of the mass accretion rate on time-scales comparable to the orbital period of the binary. As a result, SMBHBs may be recognized by the periodic modulation of their brig...
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ژورنال
عنوان ژورنال: Monthly Notices of the Royal Astronomical Society
سال: 1999
ISSN: 0035-8711,1365-2966
DOI: 10.1046/j.1365-8711.1999.02872.x