Thermal and Dynamical Properties of CIV Absorbers

Introduction

The spectra of Quasi-Stellar Objects (QSOs) provide a unique labratory for studying the properties of the intergalactic medium (IGM). As the QSO light propegates through the IGM, gas clouds leave their mark on the spectra. By analyzing the breadth, depth, shape, and position of these absorption lines, many key properties can be determined about the gas clouds in the IGM. This study looked at the clouds rich in triply ionized Carbon (CIV) to determine their thermal and dynamical properties at redshifts between 1.5 and 3.5.

A lot is unknown about the IGM at these redshifts. It is important to study because at this stage of the universe, 90% of all of the Baryons are found in the IGM. In order to determine the total Baryonic density, the IGM must be well defined. The QSO spectra also give us clues about the evolution of galaxies. It is believed that the CIV absorbers are located in circumgalactic clouds reaching beyond the galaxy halos and are enriched by the supernovae within the galaxies.

Data

The Data comes from high resolution spectra taken from 17 QSOs using the Ultraviolet and Visible Echelle Spectrograph (UVES) on the VLT at the European Southern Observatory. These spectra have a resolution of 6.7 km/s and a signal-to-noise of 80-120 in the CIV region and 20-60 in the forest region. They were reduced and normalized using the UVES data reduction pipeline. The absorption lines were then fitted by hand using Voigt profiles.

The VLT at ESO.

Useful links

SIMBAD (Stellar/Galactic database)

NED (Extragalactic database)

UNIX tutorial

Web page basics

NASA Astrophysics Data Service