Muses | EPFL Graph Search

thumb|upright=1.7|Sarcophage des Muses, , musée du Louvre. Dans la mythologie grecque, les Muses (grec ) sont les neuf filles de Zeus et de Mnémosyne qui présidaient aux arts libéraux. Mélété, Aédé et Mnémé sont les muses béotiennes dites originales, et Calliope, Clio, Érato, Euterpe, Melpomène, Polymnie, Terpsichore, Thalie et Uranie sont les neuf muses olympiennes. Étymologie S'il est établi que leur nom (sing. []) reflète un ancien *montya, l'étymologie de cette dernière forme reste incertaine. Une hypothèse fait dériver le terme de la racine indo-européenne *men- / *mon- présente dans et dans . Mnémosyne dérivant du grec , cela ferait des Muses, les Filles de la Mémoire. Tandis qu'une autre hypothèse propose de rattacher le mot à la racine *mont- du latin mons (« montagne »), et faire d'elles, primitivement, les nymphes des monts Olympe ou Hélicon. Toutefois, la racine grecque se retrouve dans des mots tels que (), (). Mythe antique Les Muses apparais

Advanced gravitational lensing techniques for precision cosmology

Markus Rexroth

Gravitational lensing - the deflection of light by gravity - has greatly developed since its famous first observation in 1919, which validated Einstein's General Theory of Relativity. The strength of this effect does not depend on the nature of the mass which produces the gravitational field and thus it is a great tool to weigh both the visible and the invisible parts of the universe. Consequently gravitational lensing has become a pillar of observational cosmology over the last decades, and it is used to study the nature of Dark Matter and Dark Energy, the two mysterious quantities which dominate our universe, but are not yet understood by physics theory. The success of this endeavor rests on a thorough understanding of lensing theory and observations, including their systematics, the availability of a sufficient amount of precise data, and the development of efficient software to precisely measure these lensing effects in digital astronomical images. This thesis presents advanced techniques which can improve several of these areas. In the first part, we develop a new theoretical method to break the mass-sheet degeneracy, which prevents accurate mass determinations from lensing observations. The second part focuses on spectroscopic data from MUSE, a second-generation Integral-Field Spectrograph installed on one of the largest ground-based telescopes on earth. We present a pipeline which permits the efficient determination of the redshift of a source observed by MUSE. The redshift indicates the distance of the source from us and depends on the expansion of the universe. In addition, we use MUSE observations of a galaxy cluster to improve the determination of its total weight, including the dominant Dark Matter component. In the third part of this thesis, we investigate how we can accelerate the computation of these mass maps. In the era of big data and large surveys, computing efficiency is key to obtaining new scientific insights. We use High Performance Computing techniques like graphics card acceleration to improve the code performance and we develop a method which harnesses extra performance from using single precision without loosing the required accuracy. In the last section, we present first results from measuring flexion, a higher order lensing effect which could substantially increase the resolution of lensing mass maps and thus lead to a sharper view of structure in the universe.

EPFL2018

Inès Lamunière au colloque international des musées du XXIème siècle à Genève

Inès Lamunière

Durant deux jours, les Musées d’art et d’histoire organisent un colloque consacré à l’avenir des musées qui se concentre tout à la fois sur des problématiques culturelles, sociales, architecturales et politiques. Le monde des musées connaît depuis une trentaine d'année de profonds bouleversements. Les mutations démographiques, l’urbanisation, la numérisation, la globalisation…, qui ont contribué à une redéfinition rapide de notre rapport au monde, ont été les facteurs de cette évolution radicale qui se manifeste par la décomposition, du moins partielle, d’une forme de modèle classique et immuable de musée. Or, si cet ancien modèle tend aujourd’hui à disparaître, aucun archétype nouveau n’est venu s’y substituer, tout du moins de manière stabilisée, et le musée du XXIe siècle semble encore devoir être défini. Ce Colloque est organisé dans le cadre de l’exposition Musées du XXIe siècle. Visions, ambitions, défis.

2017

MUSE- inspired view of the quasar Q2059-360, its Lyman alpha blob, and its neighborhood

Frédéric Courbin, Claudio Gorgoni, Pierre North

The radio-quiet quasar Q2059-360 at redshift z = 3 : 08 is known to be close to a small Lyman ff blob (LAB) and to be absorbed by a proximate damped Ly ff (PDLA) system. Here, we present the Multi Unit Spectroscopic Explorer (MUSE) integral field spectroscopy follow-up of this quasi-stellar object (QSO). Our primary goal is to characterize this LAB in detail by mapping it both spatially and spectrally using the Ly ff line, and by looking for high-ionization lines to constrain the emission mechanism. Combining the high sensitivity of the MUSE integral field spectrograph mounted on the Yepun telescope at ESO-VLT with the natural coronagraph provided by the PDLA, we map the LAB down to the QSO position, after robust subtraction of QSO light in the spectral domain. In addition to confirming earlier results for the small bright component of the LAB, we unveil a faint filamentary emission protruding to the south over about 80 pkpc (physical kpc); this results in a total size of about 120 pkpc. We derive the velocity field of the LAB (assuming no transfer effects) and map the Ly ff line width. Upper limits are set to the flux of the N v lambda 1238 1242, C iv lambda 1548 1551, Heii lambda 1640, and C i i i] lambda 1548 1551 lines. We have discovered two probable Ly alpha emitters at the same redshift as the LAB and at projected distances of 265 kpc and 207 kpc from the QSO; their Ly alpha luminosities might well be enhanced by the QSO radiation. We also find an emission line galaxy at z = 0 : 33 near the line of sight to the QSO. This LAB shares the same general characteristics as the 17 others surrounding radio-quiet QSOs presented previously. However, there are indications that it may be centered on the PDLA galaxy rather than on the QSO.

Edp Sciences S A2017

Advanced gravitational lensing techniques for precision cosmology

Markus Rexroth

EPFL2018