FIELD GALAXIES AND THEIR AGNs: NATURE VERSUS NURTURE

One of the biggest successes of the standard Big Bang cosmology is the prediction of the existence and black body nature of Cosmic Microwave Background (CMB). Observations and measurements of the CMB radiation by COBE (COsmic Background Explorer), WMAP (Wilkinson Microwave Anisotropy Probe) and Planck show an almost isotropic blackbody radiation with temperature TCMB = 2.726 ± 0.010 K (Mather et al. 1994) (Universe is very smooth on large scales > 200 Mpc), and show temperature anisotropies on angular scales of ∼90◦ (Smoot et al. 1992) (Universe is inhomogeneous on small scales represented by planets, stars, galaxies, clusters and superclusters of galaxies). As a possible explanation, theory of inflation predicts that the Universe expands exponentially for a brief period of time. During this time, matter distribution is ”flattened” and at the end of this inflationary period, it is highly homogeneous on large scales, but is locally perturbed as a consequence of quantum fluctuations (Guth and Kaiser 2005). Hence, quantum fluctuations create a perturbation field that can be described as a Gaussian random field. These primordial density perturbations grow into the gravitational instability scenario through the gravitational Jeans instability, which leads to the formation of the first structures.