Astrophysics Division
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UMR Astrophysics Instrumentation Modelisation

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Jun 14th, 2024

JWST finds more hydrocarbons in discs around very low-mass stars

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May 28th, 2024

Star birth simulated in unprecedented detail

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3rd Astro-COLIBRI multi-messenger astrophysics workshop 16/09/2024 - 20/09/2024

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The launch date of SVOM is now official; it will be launched on June 24, 2024, from Xichang, China.

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The Astrophysics Division (DAp)

A major space astrophysics laboratory

The Astrophysics Division (DAp - UMR AIM) is among the major space laboratories in France, in Europe and internationally. In direct collaboration with CNES, which is responsible for the space activities of French laboratories, DAp is strongly involved in space missions for ESA's Cosmic Vision scientific program and on bilateral missions supported by CNES. The development of astrophysics at the CEA began in partnership with CNES since its creation in the early 1960s. Astrophysics has since been a growing science with high potential for discoveries. Instruments, ever more numerous and more powerful, whether from the ground or on board satellites, make it possible to probe the universe with increased angular resolution and sensitivity across the full range of the electromagnetic spectrum. Meanwhile, modeling, particularly using computational simulations, is of increasing importance in astrophysics; astrophysical problems are mostly complex problems that involve other disciplines of physics. Astrophysics and other fields of physics enrich each other.

The Astrophysics division

The DAp-UMR AIM includes nearly 200 people, including 130 permanent staff mainly UMR AIM, a joint research unit CNRS-CEA-University Paris Cité and also of the Astroparticle and Cosmology UMR APC, CEA-CNRS -University Paris Cité-Paris Observatory -PSL-CNES . The Astrophysics Service brings together researchers, engineers and technicians from the Astrophysics Division at CEA Irfu as well as research engineers at Dedip Irfu,  University Paris Cité and CNRS.

 

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Developing instruments

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Modelling the Universe

picto 5 Modelisation

Magmist

Du milieu interstellaire diffus aux étoiles. 

From diffused interstellar medium to stars.

 

Comprendre la formation des étoiles reste l'un des plus grands défis de l'astronomie moderne. Dans ce domaine, les progrès ont été limités pour deux raisons principalement : 

  • l'énorme dynamique des échelles spatiales et temporelles pertinentes
  • la grande variété et de la non-linéarité des processus physiques impliqués dans la formation des étoiles.


Le but de ce projet est de fournir une image complète et cohérente du processus de formation des étoiles en suivant de manière autoconsistante l'évolution de la matière interstellaire depuis le gaz très diffus jusqu'aux proto-étoiles.


Ce projet poursuit deux objectifs :

  1. parvenir à une compréhension globale du processus de formation des étoiles, en particulier en élucidant le lien entre les propriétés physiques du milieu interstellaire à grande échelle et les caractéristiques des proto-étoiles, telles que leur masse, leur magnétisation et leur moment angulaire ; 
  2. fournir une meilleure compréhension de la structure, de la nature et du rôle du champ magnétique et de la turbulence des parties diffuses aux parties denses du milieu interstellaire.

Les moyens utilisés

Ceci sera réalisé en effectuant une série de simulations numériques magnétohydrodynamique (MHD*) lourdes avec un code de raffinement de maillage adaptatif tout en subdivisant le problème en trois étapes majeures, à savoir la formation de nuages moléculaires à grande échelle, la formation de noyaux de formation d'étoiles et l'effondrement des noyaux protostellaires. En particulier, l'impact du champ magnétique et les processus radiatifs seront traités de manière autoconsistante en utilisant des schémas appropriés.

A chaque étape, des comparaisons avec les modèles analytiques et les observations seront effectuées en utilisant des modèles existants ou en développant de nouveaux modèles et en calculant des observations synthétiques. Les résultats de la simulation seront également utilisés pour tester et améliorer les méthodes et les algorithmes utilisés par les observateurs pour extraire les informations physiques de leurs données. Une base de données existante, dans laquelle les résultats des simulations sont disponibles, sera développée.

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Knowledge management of data archives

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HESS

Hess

H.E.S.S.

Hess

 

Exploring the High Energy gamma ray sky

H.E.S.S   stands for "High Energy Stereoscopic System". This telescope system been designed and built by a large international collaboration which includes the DAPNIA as a member. This instrument is dedicated to the observation of high energy gamma ray sources with energies above a few tens of GeV.   The interaction of these very high energy gamma rays with the upper atmosphere creates a faint flash of blue light called "Cherenkov emission". This very fast (a few nanosecond) flash of light can be observed from the ground. Surveying the sky in the TeV energy range, which is observed by astrophysicists only since last two decades, allows the get an insight into the origin of cosmic rays and to study the acceleration of cosmic rays in various astrophysical objects such as supernovae remnants or active galactic nuclei.

The HESS experiment is located in NAMIBIA, on the Gamsberg highlands (latitude 23° 16' south, longitude 16° 30' east), at an altitude of 1800 m above sea level. It was named after a famous austrian physicist, Victor Hess (1883-1964),  who was awarded the Nobel price in physics in 1936 for discovering cosmic rays.
The HESS apparatus consists in four 12 meter telescopes at the corners of a square with 120 meter sides. Each of these telescopes has a camera at his focus.The camera are large arrays of 960 photomultipliers sensitive to blue light. These photomultipliers have a very fast response time, of the order of one nanosecond.
The sensitivity of HESS (the power to detect faint sources) is 10 times better than that of previous experiments (WHIPPLEHEGRA, CAT) with an energy threshold of 100 GeV.

HERSCHEL

Herschel

Herschel

Herschel

An Infrared and Sub-millimetre Observatory

The Herschel telescope is a scientific space mission developed by the European Space Agency (ESA) dedicated to observing the Universe in the infrared and sub-millimetre ranges (wavelengths between 60 et 670 µm), a window of the electromagnetic spectrum that is still largely unexplored. It measures 9 m in length, 4 m in diameter and will weigh over 3 metric tons upon launch. Herschel arrived at ESA in January 2008 and will be launched by an Ariane 5 rocket from Kourou on 31th, October 2008. It will then be, with its 3.5 m-diameter mirror, the largest telescope ever sent into space.

The main objectives of the mission are based on two approaches related to the question of Origins. Close to Earth, Herschel will probe the molecular clouds, which are true breeding grounds for young stars, with a view to understand the first stages in star formation. Further away, it will map out the heavens to discern galaxies at the time they were formed and thus enrich our attempts to explain the evolution of the Universe, from the Big Bang to the present.

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