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

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Molecular Spectroscopy and Laser Instrumentation for Environment

by Jean-Hugues Fillion, Mathieu Bertin - published on , updated on


Christof Janssen (Researcher - Team leader), Corinne Boursier (Ass. Prof.), Hadj Elandaloussi (Engineer), Pascal Jeseck (Engineer), Yao-Veng Té (Ass. Prof.), Thomas Zanon (Ass. Prof.), Dmitri Koshelev (PhD student).


Molecules are integral building blocks of our universe and their observation in various environments allows to improve our understanding of the microscopic processes that are linked to our origin and to the conditions of life. The interaction between matter and light is one of the preferred physical phenomena to probe these molecules in their diverse forms, states and environments. To that end, suitable technologies, reliable measurements and new experiments need to be carried out and developed.

Alignement d’une cellule d’absorption à faisceaux croisés pour des mesures de précision dans l’ozone.
C. Janssen

Research Interests & Collaborations

The main interest of the SMILE team is in the understanding of *molecular and dynamical processes* that play a role in *planetary and protoplanetary atmospheres*. Using laboratory experiments or atmospheric measurements, we particularly focus on the study of *isotope ratios* and *abundances* of small molecules (such as O3, CH4, CO, CO2, aromatic compounds, etc), which tell a history of their fate and origin.

Special research topics are: oxygen isotope anomalies in O + XO reactions, ozone formation pathways in planetary atmospheres and in the laboratory, UV and high-resolution IR spectroscopy of molecules of atmospheric and astrophysical interest, multi-spectral molecular properties, precision measurements of molecular parameters, observation and climatology of terrestrial grenhouse gases by ground based remote sensing (TCCON), and monitoring of atmospheric pollutants by spectroscopic methods.

This work is largely embedded within national (GSMA, Reims; LiPhy, Grenoble; LPL, Villetanneuse; LSCE, Gif-sur-Yvette) and international collaborations (U. Utrecht, Netherlands; U Copenhagen, Denmark; U Wuppertal, Germany; KIT Karlsruhe, Germany; U Bremen, Germany).

Based on unique and self developed tools for quantitative in-situ and remote sensing of molecules in the gas phase, we study these molecules that are of interest on a variety of scales in space and time and range from the origin of the solar system to processes in planetary atmospheres that influence the future climate on planet Earth.

Our main instruments and experimental methods comprise the Paris-FTS (link), the laser based MIS-TDLAS and PRESPASS instruments, as well as dedicated mass spectrometers, such as a MBMS system.

The SMILE group has recently teamed up with the TA group of the pole "Instrumentation, Mesure et Environnement" to build a transverse working group TASQ (french acronym for Atmospheric Remote Sensing and Quantitative Spectroscopy) within the regional research federation IPSL

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 the best environment to study the interaction between Active Galactic Nuclei (AGN) and Intra Cluster Medium (ICM) and to understand the life cycle of gas in presence of feedback. The BCGs are often surrounded by a system of filaments (e.g. Salom'e $&$ 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): How are they form? what is preventing these structures to create stars?

We studied the ALMA and MUSE date of a sample of BCGs. The radial profile of the H$alpha$/CO flux ratio is roughly constant for most of the objects. This suggests that local processes are responsible for exciting the filamentary emission. The best BCG to investigate the heating source is the NGC1275, the central giant elliptical galaxy of the Perseus Cluster, which is the X-ray brightest cluster in the sky. We have investigated cosmic rays and X-rays as likely heating sources, combining multi-wavelength line emission (from optical to far-infrared) with models produced using the photoionization and photodissociation code Cloudy. We have fully constrained the model of the ionized phase and pushed the analysis to the molecular phase. We showed that using X-ray emission as the main heating source, all of the ionized line emission can be reproduced. We found that to reproduce [OI]63$mu$m line, a small filling factor of the photodissociation phase is necessary. Finally, we also showed that adding an additional dense phase or an extra pressure component is required to robustly reproduce 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
Vendredi 7 février 2020, 14h00
Salle de l'atelier, Paris
Redistribution of angular momentum from core to disk scales in Class 0 stars
Mathilde GAUDEL
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