- Nombre : GALACTIC TAPHONOMY: KINEMATICS, STELLAR POPULATIONS AND DARK MATTER CONTENT OF FOSSIL GROUPS
- Número/Código : G/2011B/17
- Nombre Concurso : CONCURSO PROPUESTAS DE OBSERVACIÓN ASTRONÓMICA PARA TIEMPO CHILENO EN EL OBSERVATORIO GEMINI SUR 2011B
- Año Concurso : 2011
- Tiempo Asignado : 12.5 horas
With their anomalous luminosity functions, fossil groups are believed to be very old systems where all L* galaxies have merged into a single bright central galaxy due to dynamical friction. These old ages clash with the X-ray observations which show an absence of cool cores, and with preliminary stellar population analyses which show rather intermediate ages. The high dark matter concentrations also found with X-ray observations, although in agreement with an old formation, are hard to reconcile with the simulation expectations for their masses. Relatively little is known in the optical regime. Hereby we propose deep spectroscopic observations of two central fossil group galaxies, which are also among the nearest fossil systems: ESO552-G020 and ESO306-G017. With these observations we will address several unexplored subjects such as the internal kinematics, dark matter distribution through dynamical analysis, ages, metallicities and the timescale of the stellar formation, giving the first detailed optical portrait of these systems.