Astronomy with integral field spectroscopy:: observation, data analysis and results

Abstract

With a new generation of facility instruments being commissioned for 8 metre telescopes, integral field spectroscopy will soon be a standard tool in astronomy, opening a range of exciting new research opportunities. It is clear, however, that reducing and analyzing integral field data is a complex problem, which will need considerable attention before the full potential of the hardware can be realized. The purpose of this thesis is therefore to explore some of the scientific capabilities of integral field spectroscopy, developing the techniques needed to produce astrophysical results from the data. Two chapters are dedicated to the problem of analyzing observations from the densely-packed optical fibre instruments pioneered at Durham. It is shown that, in the limit where each spectrum is sampled by only one detector row, data maybe treated in a similar way to those from an image slicer. The properties of raw fibre data are considered in the context of the Sampling Theorem and methods for three dimensional image reconstruction are discussed. These ideas are implemented in an IRAF data reduction package for the Thousand Element Integral Field Unit (TEIFU), with source code provided on the accompanying compact disc. Two observational studies are also presented. In the first case, the 3D infrared image slicer has been used to test for the presence of a super-massive black hole in the giant early-type galaxy NGC 1316. Measurements of the stellar kinematics do not reveal a black hole of mass 5 x l0(^9)M©, as predicted from bulge luminosity using the relationship of Kormendy & Richstone (1995). The second study is an investigation into the origin of [Fell] line emission in the Seyfert galaxy NGC4151, using Durham University's SMIRFS-IFU. By mapping [Fell] line strength and velocity at the galaxy centre, it is shown that the emission is associated with the optical narrow line region, rather than the radio jet, indicating that the excitation is primarily due to photoionizing X-rays.Finally, a report is given on the performance of TEIFU, which was commissioned at the William Herschel Telescope in 1999. Measurements of throughput and fibre response variation are given and a reconstructed test observation of the radio galaxy 3C 327 is shown, demonstrating the functionality of the instrument and software.