THE UNITED KINGDOM INFRARED TELESCOPE
ANNUAL REPORT
1997

2. Scientific Highlights from 1997

This section briefly presents highlights of observations made during Semesters 97A and 97B.

2.1. Galaxies and Quasars

Dr. Lance Miller and collaborators used UKIRT's excellent image quality to study the dependency of quasar luminosity on the mass of a quasar's host galaxy, and succeeded in obtaining resolutions of 0.4-0.7 arcseconds in images requiring many hours of integration. An example is shown in Figure 1. They have found that a massive host galaxy appears to be required for the formation of any luminous quasar, but that there does not appear to be a straightforward dependence of quasar luminosity on the host luminosity.

 
Figure 1: The host galaxy of the redshift 0.384 quasar PG00 43+039, observed on UKIRT with tip/tilt to obtain a K-band image FWHM of about 0.4 arcseconds. A point-source contribution due to the quasar has been subtracted. Contours are plotted at equal logarithmic intervals at 0.8, 2, 5, 13, 32 and 80% of the peak signal. The galaxy accounts for 18% of the light from the quasar and has an absolute K magnitude of -26.0. The inset shows an image of a nearby star used to determine the psf, shown to the same scale with contours plotted at the same fixed multiples of the peak signal.

Dr. Max Pettini continued to exploit CGS4's as yet unequalled sensitivity between OH lines in the short wavelength infrared, by measuring the strengths of H and O III emission lines in ``Lyman break'' galaxies at redshifts of 3 and greater. Emission lines have now been detected at levels about 10 times weaker than the limits reached in previous searches. The rates of star formation in these early-universe galaxies are found to be 20-300 solar masses per year. The velocity dispersions combined with sizes measured from Hubble Space Telescope images, implies masses of about solar masses, comparable to the mass of the Milky Way bulge. These results support the view that Lyman break galaxies are the progenitors of today's massive galaxies.