I. Introduction. Astrophysics. Astrophysics at the CEA Activity Report. Service d'astrophysique DSM - DAPNIA 2

Transcription

1 Activity Report I. Introduction Astrophysics The aim of astrophysics is to understand the origin, history and future of the Universe (formation and evolution of stars, planets, galaxies, galaxy clusters, etc.). Astrophysics is a fast-growing science because of the great potential it offers for new discoveries; for example, the nature of 95% of the Universe is totally unknown. Increasingly numerous and powerful ground- and spacebased instruments have made it possible to probe the Universe with greater angular resolution and sensitivity, through the entire electromagnetic spectrum. At the same time, modeling, particularly by means of computer simulations, has taken a growing role in astrophysics; astrophysical problems are typically complex and call upon various fields within physics. Astrophysics and the other fields of physics are mutually enriching. On the one hand, astrophysics relies upon other fields to understand the cosmos; on the other, the cosmos is a great natural laboratory harboring the most extreme conditions: the longest distances, the greatest timescales, the strongest gravitational fields close to black holes, particles with the highest energy, and so on It thus enables us to go to the limits of current physics and perhaps beyond. It is one of the reasons why DAPNIA, dealing with astrophysics, particle physics and nuclear physics, was set up in Astrophysics at the CEA The presence of astrophysics within the CEA has always benefited astrophysics and been beneficial to the CEA. Astrophysical activity began in the 1960s. At that time, the CEA wanted to develop nuclear (both civil and military) and had already acquired wide experience in instrumentation for detecting X and γ radiation. At the same time, space studies were starting to develop with the foundation of CNES in Since X and γ radiations from space are absorbed by the atmosphere, it was natural to combine the expertise of the CEA and CNES to develop high-energy astrophysics. Thus, SAp (Service d'astrophysique) became one of the first French space laboratories dedicated to astronomy and, in partnership with CNES, it participated in most of the major astronomy projects investigating cosmic radiation (HEAO, Ulysse), γ radiation (CosB, Sigma, Integral) and X radiation (XMM). ESA : COS-B ( ) IKI : GRANAT-SIGMA ( ) ESA : XMM ( ) ESA : INTEGRAL ( ) Since the 1960s, the SAp in partnership with CNES is involved in high energy space instrumentation. Since the 1980s, the CEA diversified and developed a high technology center. Astrophysics is a driver of technological developments ripe for industrial use because the instruments used in astrophysics require exceptionally high performances, if they are to observe the faintest objects in the Universe. Astrophysics has also become a multiple wavelength science. SAp kept up with the evolutions in astrophysics and the CEA, by diversifying towards a new sphere of excellence: the detection of thermal infrared radiation, based on technological developments in detectors made at Léti, CEA Grenoble, for astrophysics applications. SAp consequently took charge of the development of the Isocam camera on board the ISO satellite (November 1995 May 1998), and participated in the Cirs instrument for the Cassini mission (launch 1997, insertion into orbit around Saturn 30 June 2004). Development at Léti of new types of detectors required in astrophysics is currently Service d'astrophysique DSM - DAPNIA 2

2 Introduction continuing with the production of bolometer arrays as part In future years, it is expected that technological development and contracting in major space projects will continue to be major activities, justifying the presence of astrophysics at the CEA and giving it a special place in the astrophysics research scene. of the Pacs instrument for the Herschel mission. There are two other areas in which astrophysics looks set to develop at the CEA: computer hydrodynamics simulations, through privileged access to the large DAM computers, and astrophysical plasmas with the development in particular of laboratory astrophysics from An important activity at SA p is the study of stellar plasmas (studying the sun with SOHO observations, magnetohydrodynamics numerical simulations, laboratory experiment with large lasers). Since the 1980s, the SAp diversified in infrared instrumentation, thanks to technological developments made at CEA/DRT/LETI. experiments using large power lasers, and ultimately the Mégajoule laser at Bordeaux. "Laboratory plasmas and computer simulations" activity is strongly linked with the study of the Sun by helioseismology, an activity that began with SAp's participation in the Golf experiment on board the SoHO satellite (launched 1995). Organisation of SAp Until the end of 2001, SAp was organized into groups of engineers and researchers according to the wavelength being studied (X, γ, IR, etc.), plus a "theoretical" group and a space experiments group (Geres). At the start of 2002, SAp was reorganized into nine laboratories, five bringing physicists together to look at a particular scientific area, and four space instrumentation laboratories including one detection laboratory, combining physicists, engineers and technicians (see organization chart). One of the keys to SAp's success has been the strong link between the production of instruments and their use. This strong link is maintained by the scientific managers of the instuments. This structure also takes account of the fact that since SAp became part of DAPNIA in 1992, there has been much greater collaboration with DAPNIA's technical services, particularly on ground-based projects. As a result, SAp has been able to refocus its technical activity on aspects specific to space. At the end of 2003, SAp had 94 CEA staff (48 physicists, 28 engineers and 18 technicians), 9 CNRS staff, 7 university staff, 21 PhD students and 17 post-doctoral fellows. Relations with other Institutions SAp has always been very open to the outside, welcoming researchers from other institutes. For this reason, very close links have existed between SAp and CNRS since the mid-70s. The structure of this collaboration has, for a long time, been an associated research unit (URA 2052). In 2001, the decision was made to convert the URA to a transitional research federation (FRE2591), a 2-year temporary structure enabling the unit to evolve to a new 3 DSM - DAPNIA structure, namely a mixed research unit (UMR). Since 1997, SAp has been associated with Paris-7 University through the γg team. This mixed team (four research academics and four physicists from the CEA in 1997) had expanded to six research academics and 13 physicists from the CEA at the time of the 2001 four-year plan. Service d'astrophysique

3 Introduction From 1 January 2005, relations with our partners will be strengthened by the creation of two mixed research units (UMRs). The astrophysics of multiple-scale interactions (AIM) UMR will include most of the physicists from the CEA and CNRS, and the university staff currently in SAp. In addition, seven physicists from the service will be part of the astroparticles and cosmology (APC) UMR, which will be located at the Tolbiac campus of Paris-7 University. Several physicists from SAp are also members of the Research Federation associated with the Laser Plasma Institute. Head of SAp : P.O. Lagage Deputy Head : M.Talvard CSTS SPACE INSTRUMENTATION INTERPRETATION Detection B. Cordier Star and Planet Formation P. André Calibration, Data Reduction Detectors O.Limousin Stellar Plasmas Nuclear Astrophysics S. Turck-Chièze AIT C.Bonnin High Energy Astrophysics P.Ferrando Electronics C.Cara Cosmology and Galaxy Evolution D.Elbaz System Y.Rio Theory and Modelisation J.P.Chieze Product Assurance J.Fontignie SAp organization chart Principal Research Programs and Projects SAp is principally working in the following areas: the birth of stars and planets (molecular cloud fragmentation, early stages in the formation of stars, circumstellar disks, Saturn's rings, etc.); the life of stars (magneto-hydrodynamic phenomena of stellar plasmas, activity of young stars, the Sun, massive stars and presupernovae, etc.); the final stages in the life of stars (formation of black holes, X-ray binaries, microquasars, explosion of supernova, supernova remnants, gamma-ray bursts, etc.); the structure of the Universe (history of the formation and evolution of stars, galaxies and their active nuclei, galaxy clusters, the large scale structure of the Universe, etc.). This research is conducted using multiple wavelength observations, in particular using instruments in which DAPNIA has participated, computer simulations and theoretical studies. The service currently finds itself in an exceptional position, with four experiments in space, SoHO launched in December 1995, Cassini launched in October 1997, XMM launched in December 1999 and Integral launched in October 2002, as well as three ground-based experiments, Megacam, Hess and VISIR. Service d'astrophysique SAp is involved in the scientific exploitation of instruments for gound-based telescopes, built by SAp, SEDI and SIS. By 2007 it will have 12 instruments in exploitation, which will require excellent organization in order to maximize scientific returns and which justifies a request for an increase in staffing levels. DSM - DAPNIA 4

4 Introduction Scientific publications The table below summarizes the scientific publications for the years 2001, 2002 and Of the 315 articles published between 2001 and 2003 in class A journals, five were published in Science and one in Nature. Three prizes and distinctions have been awarded to members of SAp: 2002, Jacques Paul: Massey Award from the Royal Society and the Committee on Space Research; 2003, Pierre-Alain Duc: Young Researcher Award from the French Astronomy and Astrophysics Society (SF2A); 2003, Félix Mirabel: received as doctor honoris causa by the University of Barcelona. Publication by Year Class A journals Conferences Thesis defended Students starting a thesis HDR The motion of Cygnus X-1 (red arrow) and of the parent cluster of stars (yellow arrow) indicate that this black hole was formed without an energetic and luminous Supernova explosion (Mirabel et al. Science 2003). The mid infrared images obtained with the ISOCAM camera on-board the ISO satellite have revealed a crucial phase in galaxies lifetime during which they experiment a burst of star formation (Elbaz & Cesarsky, Science 2003). First images in X-rays of jets expanding from a microquasar (Corbel et al. Science 2002). Instrumental projects SAp, with the support of SIS and SEDI, is involved in the realization of three major space instruments (the PACS and SPIRE HERSCHEL instruments and MIRI, the midinfrared instrument to equip the JWST telescope, the successor of the Hubble Space Telescope). SAp also participates in the GLAST and PLANCK projects but only on software for data analysis. Eclairs project, proposed in response to the CNES call for tenders on microsatellites, as well as the associated Research & Development studies on the detection of γ radiation using Cd(Zn)Te "polycells", the detection of X and γ radiation continues to be an area of excellence for SAp. SAp is involved in the realisation of three major space instruments, the PACS and SPIRE Herschel instruments (launched in 2007) and MIRI, the mid-infrared instrument to equip the JWST (Launched in 2011). SAp is actively preparing the future by leading feasibility studies of five projects, four space projects and one ground-based project. With the Simbol-X project, proposed in response to the CNES call for tenders on projects based on spacecrafts flying in formation, and the CdZnTe detector in the framework of the R&D conducted with SEDI Helioseismology is a powerful tool for studying the inside of the Sun. Gaining an accurate understanding of the Sun is an essential step in advancing knowledge of the way stars evolve. The Golf-NG project, proposed in response to the CNES call for tenders on microsatellites, the principal aim of which is to detect gravitational modes and to understand activity cycles, could follow on from SOHO-Golf. 5 DSM - DAPNIA Service d'astrophysique

5 Introduction A space mission to study dark matter and dark energy using a wide-field optical and infrared telescope in space, will almost certainly take place. SAp is playing a leading role in Europe to promote a rapid development of such a mission (the DUNE project has been proposed to CNES). Based on the technological progress achieved with the development of submillimetre detector arrays as part of the Herschel project, plans for a large-field submillimetre instrument on a large ground-based telescope are being drawn up. Content of this report This activity report deals with years These years have been particularly productive, both in terms of scientific results, and in terms of instrumentation. The report is organized as follows. In chapter 2, the first results from INTEGRAL, major CEA program, are enlightened. In chapter 3, emphasis is put on examples of contributions of astrophysics to fundamental physics (dark energy, solar neutrinos). The five subsequent chapters are dealing with the activity of the five interpretation laboratories. Chapter IX is a general presentation of the space instrumentation laboratories. One of these laboratories is the detection laboratory; the Research and Development conducted by the laboratory is presented in chapter X. One key element in the long chain from instrumental ideas to scientific publications is data reduction; that is why we are participating to several data centres (see chapter XI). To be at the front line of data reduction, we are using the latest signal processing algorithms, especially those developed by specialists from SEDI (see chapter XII). For specific information on the individual instrumental projects, please refer to the following web page address : Service d'astrophysique DSM - DAPNIA 6