A Survey for Large Separation Lensed FIRST Quasars

Details A Survey for Large Separation Lensed FIRST Quasars A Survey for Large Separation Lensed FIRST Quasars

2001-01-15

arxiv.org/abs/astro-ph/0101230v1

Mon.Not.Roy.Astron.Soc. 324 (2001) 463

Astronomy and Astrophysics

Astrophysics

10 pages, accepted for publication in MNRAS

Scientific paper

10.1046/j.1365-8711.2001.04326.x

Little is known about the statistics of gravitationally lensed quasars at large (7''-30'') image separations, which probe masses on the scale of galaxy clusters. We have carried out a survey for gravitationally-lensed objects, among sources in the FIRST 20cm radio survey that have unresolved optical counterparts in the digitizations of the Palomar Observatory Sky Survey. From the statistics of ongoing surveys that search for quasars among FIRST sources, we estimate that there are about 9100 quasars in this source sample, making this one of the largest lensing surveys to date. Using broad-band imaging, we have isolated all objects with double radio components separated by 5''-30'', that have unresolved optical counterparts with similar BVI colours. Our criteria for similar colours conservatively allow for observational error and for colour variations due to time delays between lensed images. Spectroscopy of these candidates shows that none of the pairs are lensed quasars. This sets an upper limit (95% confidence) on the lensing fraction in this survey of 3.3x10^-4, assuming 9100 quasars. Although the source redshift distribution is poorly known, a rough calculation of the expected lensing frequency and the detection efficiencies and biases suggests that simple theoretical expectations are of the same order of magnitude as our observational upper limit. Our procedure is novel in that our exhaustive search for lensed objects does not require prior identification of the quasars in the sample as such. Characterization of the FIRST-selected quasar population will enable using our result to constrain quantitatively the mass properties of clusters.

Affiliated with

Also associated with

No associations

Rating

A Survey for Large Separation Lensed FIRST Quasars does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with A Survey for Large Separation Lensed FIRST Quasars, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and A Survey for Large Separation Lensed FIRST Quasars will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-531126