LERMA UMR8112

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



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Organization of the laboratory

par Elise blanchard - publié le

LERMA’s Organizational Entities :


  • The management team : composed of the Unit Director, the 2 Assistant Directors, the Technical Director and the Administrator.


Unit Director : Benoit SEMELIN

Assistant Director : Martina WIEDNER

Assistant Director : Ludovic PETITDEMANGE

Technical Director : Jean-Michel KRIEG

Administrator : Murielle CHEVRIER


The management team can be reached at : direction.lerma@obspm.fr


  • The Laboratory Council : is the statutory body of a Research Unit. It is chaired by the Unit Director and is composed of ex-officio, elected and appointed members. It deals with all aspects of the life of the laboratory.

The Laboratory Council meets several times a year. Following each meeting, a report with the main points of discussion is drawn up. After validation by the members of the Council, these minutes are circulated to the whole laboratory.


  • The Scientific Council : its mission is to advise the Unit Director in the scientific choices relating to the prospective, creation, life and suppression of research themes and projects as well as the follow-up of the operations selected (financing, technical support, progress). The work of the SC must guide the management in its decision-making and scientific choices.


  • The administrative team : consists of 6 agents. It works closely with the administrative services of the CNRS (Ile de France-Meudon delegation (DR5) and INSU), the Paris Observatory (OP), Sorbonne University (SU) and Cergy Paris University (CYU).

LERMA’s administrative team supports research activities by ensuring the administrative management of permanent and temporary staff, the financial management of all allocated funds and the monitoring of research contracts.




Organization charts :


Technical organization chart

Administrative organization chart





Computer organization chart

Séminaires à venir

Vendredi 22 janvier 2021, 14h00
via Zoom , Paris
Dark matter halo response to baryons
Jonathan FREUNDLICH
Observatoire astronomique de Strasbourg
résumé :
While cold dark matter numerical simulations predict steep, `cuspy' density profiles for dark matter halos, observations favour shallower `cores'. The introduction of baryonic physics alleviates this discrepancy, notably as feedback-driven outflow episodes contribute to expand the dark matter distribution for stellar masses between 10^7 and 10^10 Msun. I will first present a parametrization of dark matter halo density profiles with variable inner slope and concentration that enables to describe the variety of halo responses to baryons and has analytic expressions for the gravitational potential, the velocity dispersion, and lensing properties. This parametrization provides a useful tool to study the evolution of dark matter haloes, to model rotation curves of galaxies and gravitational lenses, and to be implemented in semi-analytical models of galaxy evolution. I will then present two theoretical models describing core formation in dark matter haloes. In the first one, sudden bulk outflows induced by stellar feedback reorganise the halo mass distribution while it relaxes to a new equilibrium. In the second one, small stochastic density fluctuations induce kicks to collisionless particles that progressively deviate them from their orbits. Both models are tested against numerical simulations and provide a simple understanding of the transition from cusps to cores by feedback-driven outflows.
 
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