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 15 novembre 2019, 14h00
Salle de l'atelier, Paris
Excitation mechanisms in the intracluster filaments around the Brightest Cluster Galaxies
Fiorella POLLES
résumé :
In the center of galaxy clusters lie giant elliptical galaxies, the Brightest Cluster galaxies (BCGs). These galaxies are often surrounded by a system of filaments (e.g. Salomé & Combes 2003) that emit in a wide range of wavelengths, illustrating the multi-phase nature of these streams. Many of these filaments do not have strong on-going star formation and the photoionization by stellar emission cannot reproduce their emission (Johnstone et al. 2007): what is preventing these structures to create stars and what heating mech- anisms are involved, are still open questions. I have investigated cosmic rays and X-rays as likely heating sources, combining multi-wavelength line emission (?23 lines: from optical to far-infrared) with Cloudy models (Polles et al in prep.). I have fully constrained the model of the ionized phase combining for the first time optical-to-infrared emission and self-consistent multi-phase models, pushing the analysis to the molecular phase on three off-nuclear regions of NGC 1275, the central giant elliptical galaxy of the Perseus Cluster. We showed that using X-ray emission as the main heating sources, all of the ionized line emission can be reproduced. We found that to reproduce [OI]63?m line, a small filling factor of the photodissociation phase is necessary. We also showed that adding an additional dense phase or an extra pressure component is required to robustly re- produce the H2 line emission.
Vendredi 29 novembre 2019, 14h00
Salle de l'atelier, Paris
The size of galaxies in the era of ultra-deep imaging
Nushkia CHAMBA
Instituto de Astrofisica de Canarias
résumé :
While the effective radius is a robust parameter, its use to
characterise galaxy sizes has provided a counter-intuitive definition of
what the actual extent of a galaxy is. Current deep imaging therefore
offers a unique opportunity to critically review the convention that the
size of a galaxy is its effective radius and rethink how one best
measures the extent of galaxies using a physically motivated parameter.
We introduce a new definition of galaxy size based on the gas density
threshold for star formation in galaxies. Remarkably, our new size
definition not only captures what the human visual system identifies as
the edge of a galaxy, but also dramatically decreases the scatter in the
stellar mass - size plane by a factor of three. Our size parameter
unifies galaxies spanning five orders of magnitude in stellar mass on a
single mass-size relationship. To demonstrate the implications of our
results, we show that ultra-diffuse galaxies have the same sizes as
regular dwarfs when a size indicator that describes the global structure
of galaxies is used. This work may be extended for larger samples of
galaxies using upcoming wide, deep imaging surveys.
Vendredi 6 décembre 2019, 14h00
Salle de l'atelier, Paris
Is accretion-driven turbulence a key process for galaxy growth ?
Vendredi 13 décembre 2019, 14h00
Salle de l'atelier, Paris
Falsifying the concordance of cosmology with the large-scale structures
Yonsei University, Seoul
Vendredi 24 janvier 2020, 14h00
Salle de l'atelier, Paris
The accretion-ejection connection in planet-forming disks. New perspectives from high angular resolution observations
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