Cosmology

Abstract:

Using a new radio sample, 6C* designed to find radio galaxies at z > 4 along with the complete 3CRR and 6CE sample we extend the radio galaxy K - z relation to z similar to 4.5. The 6C* K - z data significantly improve delineation of the K - z relation for radio galaxies at high redshift (z > 2). In a spatially flat universe with a cosmological constant (Omega(M) = 0.3 and Omega(A) = 0.7), the most luminous radio sources appear to be associated with galaxies with a luminosity distribution with a high mean (approximate to 5L*), and a low dispersion (sigma similar to 0.5 mag) which formed their stars at epochs corresponding to z greater than or similar to 2.5).

Abstract:

To initiate this discussion I raised five topics (i) the physical mechanisms that give rise to the global relationships observed in early type galaxies, (ii) the origin of the environmental dependences of galaxy properties such as morphology and mean age, (iii) lessons from galaxy populations in intermediate redshift clusters, (iv) the role of black holes in galaxy evolution and (v) the order of formation of different galactic subcomponents. Comments and questions ranged over these and other issues and a lively discussion ensued.

Abstract:

This contribution describes results obtained with the GALICS model (for Galaxies In Cosmological Simulations), which is a hybrid model for hierarchical galaxy formation studies, combining the outputs of large cosmological N-body simulations with simple, semi-analytic recipes to describe the fate of the baryons within dark matter halos. Designed to predict the overall statistical properties of galaxies, with special emphasis on the panchromatic spectral energy distribution emitted by galaxies in the UV/optical and IR/submm wavelength ranges, such an approach can be used to predict the galaxy luminosity function evolution from the ultraviolet to far infrared, along with individual galaxies star formation histories.

Abstract:

The first of two Gemini Multi Object Spectrographs (GMOS) has recently begun operation at the Gemini-North 8m telescope. In this presentation we give an overview of the instrument and describe the overall performance of GMOS-North both in the laboratory during integration, and at the telescope during commissioning. We describe the development process which led to meeting the demanding reliability and performance requirements on flexure, throughput and image quality. We then show examples of GMOS data and performance on the telescope in its imaging, long-slit and MOS modes. We also briefly highlight novel features in GMOS that are described in more detail in separate presentations, particularly the flexure compensation system and the on-instrument wavefront sensor. Finally we give an update of the current status of GMOS on Gemini-North and future plans.