  The nature of dark matter is one of the most important unsolved questions in
science. Some dark matter candidates do not have sufficient nongravitational
interactions to be probed in laboratory or accelerator experiments. It is thus
important to develop astrophysical probes which can constrain or lead to a
discovery of such candidates. We illustrate this using state-of-the-art
measurements of strong gravitationally-lensed quasars to constrain four of the
most popular sterile neutrino models, and also report the constraints for other
independent methods that are comparable in procedure. First, we derive
effective relations to describe the correspondence between the mass of a
thermal relic warm dark matter particle and the mass of sterile neutrinos
produced via Higgs decay and GUT-scale scenarios, in terms of large-scale
structure and galaxy formation astrophysical effects. Second, we show that
sterile neutrinos produced through the Higgs decay mechanism are allowed only
for mass $>26$ keV, and GUT-scale scenario $>5.3$ keV. Third, we show that the
single sterile neutrino model produced through active neutrino oscillations is
allowed for mass $>92$ keV, and the 3 sterile neutrino minimal standard model
($\nu$MSM) for mass $>16$ keV. These are the most stringent experimental limits
on these models.
