DM's Thesis


High Resolution Studies of the Lyman α Forest

This page contains my Ph.D. thesis, and also my physics honours year report. The topic is optical spectroscopy of QSOs (more commonly known as quasars to the general public), which is in the field of astrophysics. I made most of the observations used in this thesis at the 3.9 metre Anglo-Australian Telescope at Siding Springs, near Coonabarabran, New South Wales.

Abstract

This thesis presents a study of the Lyman α forest clouds along the sightlines to the high-redshift QSOs 1101-264 and 2348-147. A preliminary study is made of a detailed simulation of a QSO spectrum in order to characterise the biases present in the data reduction and analysis techniques. The information gained is used to aid the interpretation of several observational properties of the Lyman α clouds:

The metal line systems in the spectra of the QSOs are also described and a search is made for the presence of metals in Lyman α forest systems. Some observations on the shapes of the QSO Lyman α emission line profiles are made. A comparison between various QSO sightlines is performed to gauge the validity of extrapolating information from one sightline to large regions of high-redshift space.

Contents

Links to scanned PDF files.

The scanning process

I scanned this thesis because the only electronic copy I had was backed up on to tape and deleted from the university computers when my student account was removed. When I wanted it back some years later, the tape couldn't be found. I finally decided scanning and OCR technology was adequate enough to let me scan a hardcopy. I scanned into chunks of about 70 pages or less, because the scanner page-feeder wouldn't take much more than that.

The pages appear as printed. The OCR text is hidden and accessible if you copy/paste. It seems to be pretty good for the English text, but fails to recognise any Greek characters, so you'll see some weirdness if you do that. It does allow the text to be (mostly) searchable.

Some of the pages at random in Appendix B: Spectra are rotated by 90°. The OCR seems to have recognised that the graph captions are rotated and decided to be "helpful" and rotate the page, but only did so successfully on some of the pages. I couldn't find any way to disable this auto-rotate feature.

News articles

A couple of reports about preliminary results of my thesis appeared in various newspapers, including the University of Sydney News, and The Australian. These articles are reproduced here.

Honours report

This is a shorter report I did for my physics honours year before starting my Ph.D. It's simpler work on the same topic. This PDF was scanned without OCR, so the text is not searchable or copiable.


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