The double quasar Q2138 -- 431: lensing by a dark galaxy?
نویسندگان
چکیده
منابع مشابه
The Double Quasar Q2138-431: Lensing by a Dark Galaxy?
We report the discovery of a new gravitational lens candidate Q2138-431AB, comprising two quasar images at a redshift of 1.641 separated by 4.5 arcsecs. The spectra of the two images are very similar, and the redshifts agree to better than 115 km.sec. The two images have magnitudes BJ = 19.8 and BJ = 21.0, and in spite of a deep search and image subtraction procedure, no lensing galaxy has been...
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The theoretically expected amplitude of the associations of background quasars with foreground galaxies as a result of gravitational lensing has been updated in this paper. Since the galactic matter alone yields an amplitude of quasar overdensity smaller than that observed, a special attention has been paid to the examination or re-examination of the uncertainties in the estimate of the quasar ...
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The magnification bias of large-scale structures, combined with galaxy biasing, leads to a cross-correlation of distant quasars with foreground galaxies on angular scales of the order of arc minutes and larger. The amplitude and angular shape of the cross-correlation function wQG contain information on cosmological parameters and the galaxy bias factor. While the existence of this cross-correla...
متن کاملA further discussion on quasar-galaxy associations from gravitational lensing
Quasar-galaxy associations, if they result from the effect of gravitational lensing by foreground galaxies, depend sensitively on the shape of the quasar number counts. Two kinds of quasar number-magnitude relations are predicted to produce quite different properties in quasar-galaxy associations: the counts of Boyle, Shanks and Peterson (1988; BSP) provide both positive and “negative” associat...
متن کاملar X iv : a st ro - p h / 97 09 04 9 v 1 5 S ep 1 99 7 The Double Quasar Q 2138 - 431 : Lensing by a Dark Galaxy ?
We report the discovery of a new gravitational lens candidate Q2138-431AB, comprising two quasar images at a redshift of 1.641 separated by 4.5 arcsecs. The spectra of the two images are very similar, and the redshifts agree to better than 115 km.sec. The two images have magnitudes BJ = 19.8 and BJ = 21.0, and in spite of a deep search and image subtraction procedure, no lensing galaxy has been...
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ژورنال
عنوان ژورنال: Monthly Notices of the Royal Astronomical Society
سال: 1997
ISSN: 0035-8711,1365-2966
DOI: 10.1093/mnras/291.4.811