Using the 2 degree field galaxy redshift survey to detect gravitationally lensed quasars
File(s)
Published version
Author(s)
Mortlock, DJ
Webster, RL
Type
Journal Article
Abstract
Galaxy redshift surveys can be used to detect gravitationally lensed quasars if the spectra
obtained are searched for the emission lines of quasars. Previous investigations of this
possibility have used simple models to show that the 2 degree Field (2dF) redshift survey
could yield several tens of new lenses, and that the larger Sloan Digital Sky Survey should
contain an order of magnitude more. However the particular selection effects of the samples
were not included in these calculations, limiting the robustness of the predictions; thus a
more detailed simulation of the 2dF survey was undertaken here. The use of an isophotal
magnitude limit reduces both the depth of the sample and the expected number of lenses, but
more important is the Automatic Plate Measuring survey's star±galaxy separation algorithm,
used to generate the 2dF input catalogue. It is found that most quasar lenses are classed as
merged stars, with only the few lenses with low-redshift deflectors likely to be classified as
galaxies. Explicit inclusion of these selection effects implies that the 2dF survey should
contain 10 lenses on average. The largest remaining uncertainty is the lack of knowledge of
the ease with which any underlying quasars can be extracted from the survey spectra.
obtained are searched for the emission lines of quasars. Previous investigations of this
possibility have used simple models to show that the 2 degree Field (2dF) redshift survey
could yield several tens of new lenses, and that the larger Sloan Digital Sky Survey should
contain an order of magnitude more. However the particular selection effects of the samples
were not included in these calculations, limiting the robustness of the predictions; thus a
more detailed simulation of the 2dF survey was undertaken here. The use of an isophotal
magnitude limit reduces both the depth of the sample and the expected number of lenses, but
more important is the Automatic Plate Measuring survey's star±galaxy separation algorithm,
used to generate the 2dF input catalogue. It is found that most quasar lenses are classed as
merged stars, with only the few lenses with low-redshift deflectors likely to be classified as
galaxies. Explicit inclusion of these selection effects implies that the 2dF survey should
contain 10 lenses on average. The largest remaining uncertainty is the lack of knowledge of
the ease with which any underlying quasars can be extracted from the survey spectra.
Date Issued
2001-03-01
Date Acceptance
2000-09-12
Citation
Monthly Notices of the Royal Astronomical Society, 2001, 321 (4), pp.629-641
ISSN
0035-8711
Publisher
Oxford University Press (OUP)
Start Page
629
End Page
641
Journal / Book Title
Monthly Notices of the Royal Astronomical Society
Volume
321
Issue
4
Copyright Statement
© 2001 Oxford University Press. This is a pre-copy-editing, author-produced version of an article accepted for publication in Monthly Notices of the Royal Astronomical Society following peer review. The definitive publisher-authenticated version Daniel J. Mortlock, Rachel L. Webster, Using the 2 degree Field galaxy redshift survey to detect gravitationally lensed quasars, Monthly Notices of the Royal Astronomical Society, Volume 321, Issue 4, March 2001, Pages 629–641, https://doi.org/10.1046/j.1365-8711.2001.04065.x is available online at: https://doi.org/10.1046/j.1365-8711.2001.04065.x
Identifier
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Subjects
Science & Technology
Physical Sciences
Astronomy & Astrophysics
gravitational lensing
methods : data analysis
surveys
quasars : emission lines
quasars : general
ELLIPTICAL GALAXIES
LUMINOSITY FUNCTION
DISTRIBUTIONS
MAGNITUDES
2DF
PARAMETERS
PHOTOMETRY
CLUSTERS
CATALOG
Publication Status
Published
Date Publish Online
2001-03-11