Institut de recherche sur les lois fondamentales de l'Univers

"The ISM in Low Metallicity Environments: Bridging the Gap Between Local Universe and Primordial Galaxies"

The Herschel Dwarf Galaxy Survey is a Guaranteed Time Key Program led by Suzanne Madden.
Abstract: 
While much of what we have gleaned of the details of dust and gas properties and the processes of dust recycling and heating and cooling in galaxies has been limited to Galactic studies, with Herschel we will be able to explore these issues in low metallicity dwarf galaxies which are known by now to exhibit dust and gas properties different from more metal-rich galaxies. Because these objects are relatively nearby, it is possible to relate the observed variations in the SEDs to the actual physical phenomena occuring within the ISM of the galaxy, allowing the construction of a rich interpretative framework for unresolved, more distant galaxies in the early universe. Using the SPIRE and PACS instruments on Herschel, we propose to map the dust and gas in a 50 dwarf galaxies, sampling a broad metallicity range of 1/50 to 1/2 solar. These data, in conjunction with other ancillary data, will be used to construct the emission spectrum of the dust plus that of the gas in the most important cooling lines. The combination of these instruments onboard Herschel will provide the first opportunity to study the dust and gas in extremely low metallicity environments that have not yet experienced repeated recycling through the ISM. The interpretation of this data will open the door to comprehending primordial ISM conditions and star formation in the young universe.

Comprendre les mécanismes physiques à l’origine de l’activité éruptive du Soleil et de ses jumeaux stellaires

Understanding the physical mechanisms underlying the eruptive activity of the Sun and its stellar twins