EDP Sciences
Free access
Volume 418, Number 2, May I 2004
Page(s) 387 - 392
Section Cosmology (including clusters of galaxies)
DOI http://dx.doi.org/10.1051/0004-6361:20040049

A&A 418, 387-392 (2004)
DOI: 10.1051/0004-6361:20040049

Flux-limited strong gravitational lensing and dark energy

D.-M. Chen

National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012, PR China
(Received 23 June 2003 / Accepted 15 January 2004 )

In the standard flat cosmological constant ( $\Lambda$) cold dark matter (CDM) cosmology, a model of two populations of lens halos for strong gravitational lensing can reproduce the results of the Jodrell-Bank VLA Astrometric Survey (JVAS) and the Cosmic Lens All-Sky Survey (CLASS) radio survey. In such a model, lensing probabilities are sensitive to three parameters: the concentration parameter  c1, the cooling mass scale  $M_{\rm c}$ and the value of the CDM power spectrum normalization parameter  $\sigma_8$. The value ranges of these parameters are constrained by various observations. However, we found that predicted lensing probabilities are also quite sensitive to the flux density (brightness) ratio  $q_{{\rm r}}$ of the multiple lensing images, which has been a very important selection criterion of a sample in any lensing survey experiments. We re-examine the mentioned above model by considering the flux ratio and galactic central Super Massive Black Holes (SMBHs), in flat, low-density cosmological models with different cosmic equations of state  $\omega$, and find that the predicted lensing probabilities without considering  $q_{{\rm r}}$ are over-estimated. A low value of  $q_{{\rm r}}$ can be compensated for by raising the cooling mass scale  $M_{\rm c}$ in fitting the predicted lensing probabilities to JVAS/CLASS observations. To determine the cosmic equation of state  $\omega$, the uncertainty in  $M_{\rm c}$ must be resolved. The effects of SMBHs cannot be detected by strong gravitational lensing methods when  $q_{{\rm r}}\leq 10$.

Key words: cosmology: theory -- cosmology: gravitational lensing

© ESO 2004