Tracing dark energy with quasars

Abstract

The nature of dark energy, driving the accelerated expansion of the Universe, is one of the most important issues in modern astrophysics. In order to understand this phenomenon, we need precise astrophysical probes of the universal expansion spanning wide redshift ranges. Quasars have recently emerged as such a probe, thanks to their high intrinsic luminosities and, most importantly, our ability to measure their luminosity distances independently of redshifts. Here we report our ongoing work on observational reverberation mapping using the time delay of the Mg II line, performed with the South African Large Telescope (SALT). The concept of dark energy was introduced in the process of understanding the evolution of the Universe. This is one of the most interesting topic in modern astronomy followed by the discovery of the accelerated expansion of the Universe. Precise measurement of this effect is a key to understand the nature of this medium, and we need good probes to do that. Quasars appears as an ideal candidate for this purpose as these objects are highly luminous and detected in wide range of redshift. From Big Bang to present time a lot of things happened and we are able to see amazing structures of galaxies and stars. In the beginning of Universe everything was blurred in space and the concept of dark energy was introduced in the process of understanding its evolution. The discovery of the accelerated expansion of the Universe gives us possibility to define new interesting topics in modern astronomy. Although there are some theoretical explanation for the existence of dark energy, yet it has remained the biggest puzzle among the astronomers and physicist.