Quasars resolved?
نویسندگان
چکیده
منابع مشابه
Do 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...
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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...
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Big Bang Nucleosynthesis (BBN) is the synthesis of the light nuclei, Deuterium (D or 2H), 3He, 4He and 7Li during the first few minutes of the universe. In this review we concentrate on recent data which give the primordial deuterium (D) abundance. We have measured the primordial D/H in gas with very nearly primordial abundances. We use the Lyman series absorption lines seen in the spectra of q...
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We present the results of the “Quasars near Quasars” (QNQ) survey, a CCD-based slitless spectroscopic survey for faint V <∼ 22 quasars at 1.7 <∼ z <∼ 3.6 on 18 26.2 × 33.5 fields centred on bright quasars at 2.76 < z < 4.69. In total 169 quasar candidates with emission lines were selected from the extracted flux-calibrated spectra on the basis of well-defined automatic selection criteria follow...
متن کاملBinary 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...
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ژورنال
عنوان ژورنال: Nature
سال: 1982
ISSN: 0028-0836,1476-4687
DOI: 10.1038/295556a0