## 6. Gravitational lensingIn a recent paper Marri & Ferrara (1998) study the effects of
gravitational lensing (GL) on high- For the SCDM model, which yields the highest magnification, we find
that the increase in the total number of core collapse SNe is only a
few percent when using the NGST limits
( = 30.2 and
= 31.4). The effects are even
smaller for the shorter wavelength bands. The reason for the small
effect is that with the faint limits of the NGST almost all SNe up to
4 are detected even without
magnification, and that the number of SNe with even higher More interesting, for SNe with 4 we find, when using the NGST M´ limit, an increase by 20% of the predicted counts. For SNe with 9 the increase is 40%. It should, however, be noted that estimates presented by Porciani & Madau (1998) give a much lower probability for substantial magnification compared to the Marri & Ferrara results used in the estimates above. The reason for this seems to be that Marri & Ferrara assume point-like lenses, whereas Porciani & Madau use a more realistic mass distribution characterized by singular isothermal spheres. Therefore, the effects of gravitational lensing presented here could be overestimated. © European Southern Observatory (ESO) 1999 Online publication: October 4, 1999 |