LERMA UMR8112

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



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Molecules in the Universe


Molecules, ubiquitous in our atmosphere and in space, are providing powerful tools for probing the physics and chemistry of many different environments. They provide important clues for major scientific objectives such as climatology and planetology, star and planet formation and the question of the origin of life.


The analysis of molecular radiation under various extreme conditions requires nowadays, a high level of knowledge in molecular science which has to support a wealth of observational data arising from new generation of telescopes, satellites and probes. In addition, molecular processes are at the cornerstone in the evolution of matter in space.

The thematic pole “Molecules in the Universe” aims at pushing forward the current theoretical and experimental limits in molecular science in order :
(1) to obtain fundamental molecular parameters with high degree of accuracy that are essential for probing and modelling complex media and
(2) to understand and predict - at atomic and molecular levels - an increasing number of unknown molecular processes.

This pole brings together research groups leader in quantum physics/chemistry, low temperature physics, chemical physics as well as surface science researchers. It includes complementary theoretical and experimental teams based at Paris (Jussieu Campus), Meudon and Cergy-Pontoise.

The pole aims at playing a major role at the interface between molecular and astrophysics & atmospheric sciences while being fully invested in fundamental molecular and chemical physics science.

This reserach group has long standing experience in multi-disciplinary approaches and is a major actor of “Laboratory Astrophysics” (http://www.labastro.eu/), a new European Networks engaged in fundamental experimental, interpretative and computational research and modelling.
The pole contributes to the establishment and management of widely-used atomic and molecular databases and data centres (http://www.vamdc.eu/).

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Séminaires à venir

Vendredi 28 septembre 2018, 14h00
Salle de l'atelier, Paris
The [CII] emission line as a molecular gas mass tracer in galaxies at low and high redshift
Anita ZANELLA
ESO
résumé :
So far the gas conditions in main-sequence galaxies at the peak of the cosmic star formation history have been mainly investigated through the CO emission lines. However, observing the CO transitions at higher redshift becomes challenging, since the lines luminosity weakens as metallicity decreases. A powerful alternative could be the [CII] emission at 158um instead: it is one of the brightest lines in the far IR regime observed in star-forming galaxies and it is the main coolant of the interstellar medium. Local studies show that the [CII] luminosity correlates with the galaxy star formation rate (SFR), although main-sequence sources and starbursts seem to have different behaviours. At higher redshift the picture is even less clear and only samples of starbursts have been analyzed so far. To remedy this situation we have observed with ALMA a sample of 10 main-sequence sources at z ~ 2 and we complemented our sample with literature data at lower and higher redshift. We found that the [CII] luminosity correlates with galaxies' molecular gas mass, independently of their depletion time, metallicity, and redshift. This lays foundations for future explorations of the interstellar medium of starbursts and galaxies at much higher redshift (z > 4).

 
Vendredi 5 octobre 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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