--- res: bibo_abstract: - Dark Energy dominates the mass-energy content of the universe (about 73%) but we do not understand it. Most of the remainder of the Universe consists of Dark Matter (23%), made of an unknown particle. The problem of the origin of Dark Energy has become the biggest problem in astrophysics and one of the biggest problems in all of science. The major extant X-ray observatories, the Chandra X-ray Observatory and XMM-Newton, do not have the ability to perform large-area surveys of the sky. But Dark Energy is smoothly distributed throughout the universe and the whole universe is needed to study it. There are two basic methods to explore the properties of Dark Energy, viz. geometrical tests (supernovae) and studies of the way in which Dark Energy has influenced the large scale structure of the universe and its evolution. DUO will use the latter method, employing the copious X-ray emission from clusters of galaxies. Clusters of galaxies offer an ideal probe of cosmology because they are the best tracers of Dark Matter and their distribution on very large scales is dominated by the Dark Energy. In order to take the next step in understanding Dark Energy, viz. the measurement of the 'equation of state' parameter 'w', an X-ray telescope following the design of ABRIXAS will be accommodated into a Small Explorer mission in lowearth orbit. The telescope will perform a scan of 6,000 sq. degs. in the area of sky covered by the Sloan Digital Sky Survey (North), together with a deeper, smaller survey in the Southern hemisphere. DUO will detect 10.000 clusters of galaxies, measure the number density of clusters as a function of cosmic time, and the power spectrum of density fluctuations out to a redshift exceeding one. When combined with the spectrum of density fluctuations in the Cosmic Microwave Background from a redshift of 1100, this will provide a powerful lever arm for the crucial measurement of cosmological parameters.@eng bibo_authorlist: - foaf_Person: foaf_givenName: Richard foaf_name: Griffiths, Richard foaf_surname: Griffiths - foaf_Person: foaf_givenName: Robert foaf_name: Petre, Robert foaf_surname: Petre - foaf_Person: foaf_givenName: Guenther foaf_name: Hasinger, Guenther foaf_surname: Hasinger - foaf_Person: foaf_givenName: Peter foaf_name: Predehl, Peter foaf_surname: Predehl - foaf_Person: foaf_givenName: Nicholas E. foaf_name: White, Nicholas E. foaf_surname: White - foaf_Person: foaf_givenName: Bernd foaf_name: Aschenbach, Bernd foaf_surname: Aschenbach - foaf_Person: foaf_givenName: Xavier foaf_name: Barcons, Xavier foaf_surname: Barcons - foaf_Person: foaf_givenName: Hans foaf_name: Bohringer, Hans foaf_surname: Bohringer - foaf_Person: foaf_givenName: Ulrich G. foaf_name: Briel, Ulrich G. foaf_surname: Briel - foaf_Person: foaf_givenName: Lynn foaf_name: Cominsky, Lynn foaf_surname: Cominsky - foaf_Person: foaf_givenName: Michael F. foaf_name: Corcoran, Michael F. foaf_surname: Corcoran - foaf_Person: foaf_givenName: Udo foaf_name: Dinger, Udo foaf_surname: Dinger - foaf_Person: foaf_givenName: Wilhelm J. foaf_name: Egle, Wilhelm J. foaf_surname: Egle - foaf_Person: foaf_givenName: Peter foaf_name: Friedrich, Peter foaf_surname: Friedrich - foaf_Person: foaf_givenName: Zoltán foaf_name: Haiman, Zoltán foaf_surname: Haiman foaf_workInfoHomepage: http://www.librecat.org/personId=7c006e8c-cc0d-11ee-8322-cb904ef76f36 - foaf_Person: foaf_givenName: Robert foaf_name: Hartmann, Robert foaf_surname: Hartmann - foaf_Person: foaf_givenName: J. Patrick foaf_name: Henry, J. Patrick foaf_surname: Henry - foaf_Person: foaf_givenName: Horst foaf_name: Hippmann, Horst foaf_surname: Hippmann - foaf_Person: foaf_givenName: Jim foaf_name: Ingersoll, Jim foaf_surname: Ingersoll - foaf_Person: foaf_givenName: Keith foaf_name: Jahoda, Keith foaf_surname: Jahoda - foaf_Person: foaf_givenName: Del T. foaf_name: Jenstrom, Del T. foaf_surname: Jenstrom - foaf_Person: foaf_givenName: Steven foaf_name: Jordan, Steven foaf_surname: Jordan - foaf_Person: foaf_givenName: Eckhard foaf_name: Kendziorra, Eckhard foaf_surname: Kendziorra - foaf_Person: foaf_givenName: "G\x92nther" foaf_name: "Kettenring, G\x92nther" foaf_surname: Kettenring - foaf_Person: foaf_givenName: Walter foaf_name: Kink, Walter foaf_surname: Kink - foaf_Person: foaf_givenName: Norbert foaf_name: Meidinger, Norbert foaf_surname: Meidinger - foaf_Person: foaf_givenName: Takamitsu foaf_name: Miyaji, Takamitsu foaf_surname: Miyaji - foaf_Person: foaf_givenName: Joseph foaf_name: Mohr, Joseph foaf_surname: Mohr - foaf_Person: foaf_givenName: Siegfried foaf_name: Mueller, Siegfried foaf_surname: Mueller - foaf_Person: foaf_givenName: Richard F. foaf_name: Mushotzky, Richard F. foaf_surname: Mushotzky - foaf_Person: foaf_givenName: Elmar foaf_name: Pfeffermann, Elmar foaf_surname: Pfeffermann - foaf_Person: foaf_givenName: Peter foaf_name: Schuecker, Peter foaf_surname: Schuecker - foaf_Person: foaf_givenName: Axel foaf_name: Schwope, Axel foaf_surname: Schwope - foaf_Person: foaf_givenName: Mark foaf_name: Shannon, Mark foaf_surname: Shannon - foaf_Person: foaf_givenName: Lothar foaf_name: Strueder, Lothar foaf_surname: Strueder - foaf_Person: foaf_givenName: Steven J. foaf_name: Varlese, Steven J. foaf_surname: Varlese bibo_doi: 10.1117/12.552171 bibo_volume: 5488 dct_date: 2004^xs_gYear dct_isPartOf: - http://id.crossref.org/issn/0277-786X dct_language: eng dct_publisher: SPIE@ dct_title: 'DUO: The dark universe observatory@' ...