Multi-wavelength Catalogues Research Articles

Decision table for classifying point sources based on FIRST and 2MASS databases

With the availability of multi-wavelength, multi-scale and multi-epoch astronomical catalogues, the number of features to describe astronomical objects has increases. The better features we select to classify objects, the higher the classification accuracy is. In this paper, we have used data sets of stars and quasars from near-infrared band and radio band. Then best-first search method was applied to select features. For the data with selected features, the algorithm of decision table was implemented. The classification accuracy is more than 95.9%. As a result, the feature selection method improves the effectiveness and efficiency of the classification method. Moreover the result shows that decision table is robust and effective for discrimination of celestial objects and used for preselecting quasar candidates for large survey projects.

Predicting Multi-Wavelength Properties of Lyman Break Galaxies with GalICS

GalICS (for GALaxies In Cosmological Simulations) is a model of hierarchical galaxy formation which combines high resolution numerical simulations for the dark matter component with semi-analytic prescriptions for the baryonic matter. It provides us with an explicit cosmological framework to analyse observations of distant galaxies, and to understand how they evolve to become local galaxies. We use GalICS to build multi-wavelength mock galaxy catalogues which include clustering properties. We can compare them to the sample of Lyman Break Galaxies at z=3 (Steidel et al., 1996), and to deep sub-mm surveys. The predictions of the model will be detailed, and show a good agreement with the available data.