Tracing dark energy with quasars

TL;DR

This paper discusses using quasars as astrophysical probes to understand dark energy by measuring their luminosity distances through reverberation mapping of the Mg II line, aiding in studying the universe's accelerated expansion.

Contribution

It presents ongoing observational work on reverberation mapping of quasars using the Mg II line with SALT to improve dark energy constraints.

Findings

Successful measurement of Mg II line time delays

Enhanced quasar luminosity distance data for cosmology

Progress in using quasars to probe dark energy

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).