Published in 1987, "QSO Absorption Lines: Probing the Universe", eds. J.C. Blades, D.A. Turnshek and C.A. Norman


QSO ABSORPTION LINES: INTRODUCTION

W. L. W. Sargent


Palomar Observatory, California Institute of Technology


Abstract. A brief account is given of the physical properties of the heavy-element and Ly-alpha forest absorption redshift systems observed in QSO spectra. Theories for their origin are summarized. It is emphasized that the two types of absorption system have qualitatively different properties and that they are almost certainly not components of a single population as Tytler has recently claimed. Extensive new data on the heavy-element redshifts reveal clustering on velocity scales unlikely to have been produced by the motions of clouds within galaxies. Extensive absorption systems observed in the relatively wide QSO pair Q1037-2704 and Q1038-2712 and in the spectra of other QSOs in the surrounding field are described. Observations of this kind appear to represent a new way of studying the large-scale distribution of galaxies at earlier epochs in the expansion of the Universe.


Table of Contents

INTRODUCTION

PROPERTIES OF THE HEAVY-ELEMENT REDSHIFTS

PHYSICAL PROPERTIES OF THE Ly-alpha CLOUDS

RECENT DEVELOPMENTS ON THE Ly-alpha FOREST

ORIGIN OF THE HEAVY-ELEMENT REDSHIFTS

THE ORIGIN OF THE Ly-alpha FOREST LINES

NEW RESULTS ON CLUSTERING

QSO ABSORPTION LINES AND LARGE-SCALE STRUCTURE

THE QSO PAIR Q2343+1229, Q2344+1225

CONCLUSIONS

REFERENCES

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