Optical-NIR spectra of quasars close to reionization (z~ 6)

TL;DR

This paper presents high-quality optical-NIR spectra of three quasars near the reionization epoch (z~6), enabling insights into early universe processes like re-ionization and galaxy evolution.

Contribution

It provides new spectra of z~6 quasars and updates the cosmic mass density of C IV ions, enhancing understanding of early universe ionization history.

Findings

Confirmed constant trend of C IV cosmic mass density between redshifts 2.5 and 5.

Provided high-resolution spectra of three quasars at z~6.

Supported studies of re-ionization and early galaxy evolution.

Abstract

X-shooter, with its characteristics of resolution, spectral coverage and efficiency, provides a unique opportunity to obtain spectra of the highest-redshift quasars (z ~ 6) that will allow us to carry out successful investigations on key cosmological issues, from the details of the re-ionization process, to the evolution of the first galaxies and AGNs. In this paper, we present the spectra of three z ~ 6 quasars: one obtained during the commissioning of X-shooter and two in the context of our ongoing GTO programme. Combining this sample with data in the literature, we update the value of the C IV cosmic mass density in the range 4.5 < z < 5, confirming the constant trend with redshift between 2.5 and 5.