LERMA UMR8112

Laboratoire d’Études du Rayonnement et de la Matière en Astrophysique et Atmosphères



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About LERMA

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LERMA (Laboratory for Studies of Radiation and Matter in Astrophysics and Atmospheres) is a research entity operated by CNRS and four higher education institutions : Observatoire de Paris (OP), Université Pierre et Marie Curie (UPMC - Paris 6), École normale supérieure (ENS), and Université de Cergy-Pontoise (UCP). These institutions host the various LERMA research groups.

The laboratory is organized in four Research Poles :

  • "Galaxies and Cosmology" : studies of the early universe, inflation, cosmic microwave background ; epoch of reionization ; galaxy clusters ; dynamics of galaxies, dark matter ; galaxy formation and evolution ; black holes, AGN, star formation and feedback in local and high-redshift galaxies.
  • "Dynamics of the Interstellar Medium and Stellar Plasmas" : observational characterization of the ISM cycle ; star and planet formation ; ISM modeling, from diffuse gas to stars and disks, chemical diagnostics of the ISM dynamics ; modeling the transport mechanisms in circumstellar plasmas ; laboratory plasma experiments.
  • "Molecules in the Universe" : studies of gas-phase collisional and reactive processes ; VUV spectroscopy and photophysics, exobiology ; gas-solid interactions and heterogeneous catalysis, laboratory astrophysics.
  • "Instrumentation and Remote Sensing" : development of THz heterodyne instrumentation for large instrumental projects, Herschel/HIFI and JUICE/SWI ; research and development activities : HEB and SIS mixers, Schottky diodes for applications in tunable local oscillators ; Earth and planetary remote sensing, instrument software development.

These research poles are complemented by a transverse structure, dedicated to :
Technology and Research Support

Séminaires à venir

Vendredi 16 novembre 2018, 14h00
Salle de l'atelier, Paris
Quantum walks and astrophysical plasmas
Fabrice DEBBASCH
UPMC, LERMA, Paris
résumé :
Quantum walks (QWs) have been first considered by Feynman in the 1940's and later introduced systematically in the 1990's in the context of quantum information. These discrete automata are a universal quantum computation tool and their first experimental realisation is less than 10 years old (2009).

I will present some of the research conducted at the LERMA since 2012. I will explain that QWs can be viewed as models of Dirac fermions (electrons etc.) interacting with gauge fields like EM fields and gravitation and that QWs can be used to build self-consistent many body theories. These results pave the way towards new numerical simulations and laboratory experiments modelling astrophysical and cosmological relativistic quantum plasmas through QWs.
 
Vendredi 30 novembre 2018, 14h00
Salle de l'atelier, Paris
Multiscale star-formation in the Ophiuchus Molecular Cloud: from molecular clouds to brown-dwarfs formation
Bilal LADJELATE
IRAM
résumé :
From molecular clouds to stars, every step of the evolution of young stars can be observed in the submillimetric range. The Herschel Space Telescope observed, as part of the Herschel Gould Belt Survey, many molecular clouds. When these molecular clouds are fragmenting, dense prestellar cores accumulating dust and gas are forming and contracting. We performed a census of prestellar dense cores in the Ophiuchus Molecular Cloud, which appear to be coupled with filamentary structures, as part of the paradigm of star-formation inside interstellar filaments. The region was not previously known as filamentary, despite the observation of protostellar alignments. This molecular cloud is under the heavy feedback of active stars nearby seen in the structure of the molecular cloud. Oph B-11, detected with interferometric observations, is a brown dwarf precursor, which final mass will not be important enough for the final star to burn hydrogen. Their formation mechanism is not well constrained, we must find and characterize a first candidate pre-brown dwarf. Oph B-11 was detected along a nearby shock, we characterize chemically. Moreover, higher resolution studies with ALMA show a structured molecular environment and help us constrain the mechanism of formation of this kind of objects. These observations show a series of shocks in different tracers, spatially coincident with the detected position of the pre-brown dwarf, in favour of the gravo- turbulent scenario for the formation of brown dwarfs. I will discuss the legacy of Herschel in the Ophiuchus region in the filament paradigm of star-formation, and the future of these studies with the advent of new instruments, like NIKA2 and its polarimetry facility.
 
Vendredi 21 décembre 2018, 14h00
Salle de l'atelier, Paris
Astrochemistry in star forming regions : new modeling approaches
Emeric BRON
IRAM/LERMA
résumé :
Star-forming regions present rich infrared and millimeter spectra emitted by the gas exposed to the feedback of young stars. This emission is increasingly used to study the star formation cycle in other galaxies, but results from a complex interplay of physical and chemical processes : chemistry in the gas and on grain surfaces, (de)excitation processes of the atoms and molecules, heating and cooling balance,... Its understanding thus requires detailed astrochemical models that include the couplings between these processes. In this talk, I will present several examples where new modeling approaches of specific processes and their couplings proved crucial to solve persistent observational riddles : from the driving role of UV irradiation in the dynamics of photodissociation regions (PDR) to the efficient reformation of molecular hydrogen in these regions.
 
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