Final Report Summary - ARCHES (ARCHES : Astronomical Resource Cross-matching for High Energy Studies)
Observational astronomy has dramatically evolved over the last 20 years as a result of the opening up of new observing windows in the electromagnetic spectrum and of the development of efficient and large area detectors attached to ground-based and spaceborne instruments. With multi-wavelength measurements becoming available for billions of stars and galaxies, astronomy now ranks as a “big data” scientific activity and today many routine research activities rely on innovative data mining tools. However, large-scale multiwavelength observational studies remain difficult to achieve for a large majority of astronomers. One of the most challenging steps of analysis is to associate measurements present in different catalogues and observed at different wavelengths to a unique astrophysical object and to assess the corresponding association probabilities. This problem is particularly acute in the case of cosmic X-ray sources detected by the ESA XMM-Newton satellite, which due to its specific high-energy optics, yields source positions of lower precision than available at many other wavelengths. In this context, ARCHES’s main goal was to enrich the scientific usability of the catalogue of XMM-Newton sources by providing statistically qualified radio to X-ray spectral energy distributions for unresolved X-ray sources, and probabilistic identifications of extended X-ray sources with clusters of galaxies. In order to fulfil these objectives, careful assessment of the photometric and astrometric quality of multi-wavelength catalogues was first performed followed by the development i) of a forefront and so far unique multi-catalogue probabilistic cross-matching tool and ii) of an advanced integrated cluster finder using optical and near infrared imaging data to search for clusters of galaxies at any position in the sky. These tools were then applied to an enhanced and cleaned version of the XMM-Newton source catalogue to build over 200,000 spectral energy distributions of unresolved X-ray sources and over 500 clusters of galaxies candidates. Seven demonstration science cases focused on clusters of galaxies, active galactic nuclei and stellar activity highlighted the usability of ARCHES’s tools and products and, most importantly, provided important feedback to the development of the tools and the cross-matched catalogues. ARCHES tools and products were presented to the international community in a workshop held in Paris. They are now accessible through a variety of interfaces specific to the project as well as through mainstream dissemination systems such as the Centre de Données astronomiques de Strasbourg.
