عنوان

The fine-structure constant and wavelength calibration

Number

TL3sp9x7ss

.Language of Text, Soundtrack etc

انگلیسی

Title Proper

The fine-structure constant and wavelength calibration

General Material Designation

[Thesis]

First Statement of Responsibility

Whitmore, Jonathan

Name of Publisher, Distributor, etc.

UC San Diego

Date of Publication, Distribution, etc.

2011

Body granting the degree

UC San Diego

Text preceding or following the note

2011

Text of Note

The fine-structure constant is a fundamental constant of the universe -- and widely thought to have an unchanging value. However, the past decade has witnessed a controversy unfold over the claimed detection that the fine-structure constant had a different value in the distant past. These astrophysical measurements were made with spectrographs at the world's largest optical telescopes. The spectrographs make precise measurements of the wavelength spacing of absorption lines in the metals in the gas between the quasar background source and our telescopes on Earth. The wavelength spacing gives a snapshot of the atomic physics at the time of the interaction. Whether the fine-structure constant has changed is determined by comparing the atomic physics in the distant past with the atomic physics of today. We present our contribution to the discussion by analyzing three nights data taken with the HIRES instrument (High Resolution Echelle Spectrograph) on the Keck telescope. We provide an independent measurement on the fine-structure constant from the Damped Lyman alpha system at a redshift of z=2.309 (10.8 billion years ago) quasar PHL957. We developed a new method for calibrating the wavelength scale of a quasar exposure to a much higher precision than previously achieved. In our subsequent analysis, we discovered unexpected wavelength calibration errors that has not been taken into account in the previously reported measurements. After characterizing the wavelength miscalibrations on the Keck-HIRES instrument, we obtained several nights of data from the main competing instrument, the VLT (Very Large Telescope) with UVES (Ultraviolet and Visual Echelle Spectrograph). We applied our new wavelength calibration method and uncovered similar in nature systematic errors as found on Keck-HIRES. Finally, we make a detailed Monte Carlo exploration of the effects that these miscalibrations have on making precision fine- structure constant measurements

Whitmore, Jonathan

UC San Diego

Electronic name

p

[Thesis]

276903

a

Y