Powered by Indico
v3.2.9
In this diploma thesis, five galaxies from the Quasar Catalog of the Sloan Digital Sky Survey First Data Release are investigated. These galaxies have redshifts 2.5 <z <2.8, r-band magnitudes ~ 20 and according to Bentz et al. (2004) they might be extremely bright Lyman Break Galaxies (LBGs), 4-5 magnitudes brighter than an L <sub>* LBG. These Monstergalaxies have been observed in seven different optical and near-infrared broadband filters, in purpose to investigate if they really are monsters or if they have been gravitationally lensed by foreground galaxies, and also to find some properties of their stellar populations.
The photometric redshifts of the foreground galaxies in the fields have been estimated from their colors, and the velocity dispersions have been estimated using empirical scaling relations (Faber-Jackson&Tully-Fischer). These redshifts and velocity dispersions have been used to calculate the maximum magnification of the Monstergalaxies, caused by gravitational lensing. I found that none of these Monstergalaxies have been magnified more than about a factor of two, which means that they are not normal LBGs that have been gravitationally lensed.
By using spectral evolutionary synthesis models and fit these to the observations using leastχ 2 -fitting, the masses and ages of the Monstergalaxies have been estimated. The analysis showed that if these galaxies are LBGs, then they are young, moderately dusty and very massive, and these results are consistent with the results from the gravitational lensing analysis.
According to some newly published papers, these galaxies are no LBGs, but instead a rare type of Quasar Stellar Objects. Even if this is true, the gravitational lensing analysis shows that these objects are very luminous objects, and an interesting project could be to estimate the masses of the supermassive black holes in the center of the galaxies.