In article ,
Eric Flesch writes:
is there broadly a redshift dependency in
lens power, that is, lens mass? Are high-z lenses seen to be more
powerful than low-z lenses, or is that susceptible to a Malmquist
bias?

This seems difficult to measure, and I doubt the answer is known.
You'd need a low-z and high-z lensing sample with known masses.

One approach might be to use a sample of lensing galaxy clusters
whose masses are derived from velocity dispersions, but I'd expect
big systematic errors. I might be wrong, though; there are lots of
people cleverer than I am.

--
Help keep our newsgroup healthy; please don't feed the trolls.
Steve Willner Phone 617-495-7123
Cambridge, MA 02138 USA