TY - JOUR
T1 - The hubble space telescope snapshot survey. IV. A summary of the search for gravitationally lensed quasars
AU - Maoz, D.
AU - Bahcall, J. N.
AU - Schneider, D. P.
AU - Bahcall, N. A.
AU - Djorgovski, S.
AU - Doxsey, R.
AU - Gould, A.
AU - Kirhakos, S.
AU - Meylan, G.
AU - Yanny, B.
PY - 1993
Y1 - 1993
N2 - We report the concluding results of the HST Snapshot Survey for gravitationally lensed quasars. New observations of 153 high-luminosity z > 1 quasars are presented, bringing to 498 the total number of quasars observed in the survey. The new observations do not reveal new candidates for gravitational lensing. We present tables summarizing all of the snapshot observations, with measured V-magnitudes, accurate to 0.1 mag, for each of the quasars successfully observed. The tables are available on request in machine-readable form. The observed frequency of lensing of quasars into multiple images is 3-6 out of 502, depending on whether one counts candidates that are not yet securely confirmed and cases in which clusters play a role. This frequency is in the range predicted by calculations with a vanishing cosmological constant, assuming galaxies can be modeled by unevolving isothermal spheres dominated in their centers by dark matter. The observed frequency is an order of magnitude lower than expected in such models when the universe is strongly dominated by a cosmological constant. This conclusion is, however, sensitive to the model assumptions and to the precise number of actual lensed quasars.
AB - We report the concluding results of the HST Snapshot Survey for gravitationally lensed quasars. New observations of 153 high-luminosity z > 1 quasars are presented, bringing to 498 the total number of quasars observed in the survey. The new observations do not reveal new candidates for gravitational lensing. We present tables summarizing all of the snapshot observations, with measured V-magnitudes, accurate to 0.1 mag, for each of the quasars successfully observed. The tables are available on request in machine-readable form. The observed frequency of lensing of quasars into multiple images is 3-6 out of 502, depending on whether one counts candidates that are not yet securely confirmed and cases in which clusters play a role. This frequency is in the range predicted by calculations with a vanishing cosmological constant, assuming galaxies can be modeled by unevolving isothermal spheres dominated in their centers by dark matter. The observed frequency is an order of magnitude lower than expected in such models when the universe is strongly dominated by a cosmological constant. This conclusion is, however, sensitive to the model assumptions and to the precise number of actual lensed quasars.
KW - Cosmology: Observations
KW - Gravitational lensing
KW - Quasars: General
UR - http://www.scopus.com/inward/record.url?scp=12044253808&partnerID=8YFLogxK
U2 - 10.1086/172639
DO - 10.1086/172639
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AN - SCOPUS:12044253808
SN - 0004-637X
VL - 409
SP - 28
EP - 41
JO - Astrophysical Journal
JF - Astrophysical Journal
IS - 1
ER -