Gravitational Magnification of Pop III Supernovae in Hierarchical Cosmological Models: NGST Perspectives

摘要

We study the gravitational lensing magnification produced by the interveningcosmological matter distribution, as deduced from three different hierarchicalmodels (SCDM, LCDM, CHDM) on very high redshift sources, particularlysupernovae in protogalactic (Pop III) objects. By means of ray-shootingnumerical simulations we find that caustics are more intense and concentratedin SCDM models. The magnification probability function presents a moderatedegree of evolution up to $zpprox 5$ (CHDM) and $zpprox 7$ (SCDM/LCDM). Allmodels predict that statistically large magnifications, $mu simgt 20$ areachievable, with a probability of the order of a fraction of percent, the SCDMmodel being the most efficient magnifier. All cosmologies predict that above$zpprox 4$ there is a 10% chance to get magnifications larger than 3. We haveexplored the observational perspectives for Pop III SNe detection with NGSTwhen gravitational magnification is taken into account. We find that NGSTshould be able to detect and confirm spectroscopically Type II SNe up to aredshift of $z pprox 4$ in the J band (for $T_{SN}=25000$ K); this limitcould be increased up to $zpprox 9$ in the K band, allowing for a relativelymoderate magnification. Possibly promising strategies to discriminate amongcosmological models using their GL magnification predictions and very high-$z$SNe are sketched. Finally, we outline and discuss the limitations of our study.