Sökning: "Galaxy Clusters"

Visar resultat 11 - 15 av 34 avhandlingar innehållade orden Galaxy Clusters.

1. 11. Investigating the Dark Universe through Gravitational Lensing

   Författare :Teresa Riehm; Ariel Goobar; Edvard Mörtsell; Erik Zackrisson; Joachim Wambsganss; Stockholms universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; cosmology; gravitational lensing; dark matter; galaxies; galaxy clusters; Astronomy; Astronomi; Astronomy; astronomi;

   Sammanfattning : A variety of precision observations suggest that the present universe is dominated by some unknown components, the so-called dark matter and dark energy. The distribution and properties of these components are the focus of modern cosmology and we are only beginning to understand them. LÄS MER

3. 12. Search for lensed supernovae behind the galaxy cluster Abell 1689

   Författare :Tanja Petrushevska; Rahman Amanullah; Ariel Goobar; Peter Lundqvist; Stockholms universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; lensed supernovae; gravitational lensing; galaxy cluster Abell 1689; Astronomy; astronomi; fysik; Physics;

   Sammanfattning : Distant supernovae probe the history of cosmic expansion and star formation, and provide important information on their progenitor models. Investigation of supernovae type Ia for  are needed to reveal any evolution in their intrinsic properties, and thus their utility as existing distance indicators. LÄS MER

4. 13. The environment of active galactic nuclei : excess counts and the nature of their host clusters

   Författare :Margrethe Wold; Christopher D. Impey; Stockholms universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Astronomy; astronomi;

   Sammanfattning : This thesis presents observations of the galaxy environment of active galactic nuclei on galaxy cluster scales. In the first part, we quantify the galaxy environment of a sample of 40 quasars, consisting of equal fractions of radio-loud and radio-quiet sources. The sample covers a narrow range in redshift, 0.5 < z < 0. LÄS MER

5. 14. Exploring the Chemical Evolution of Globular Clusters and their Stars : Observational Constraints on Atomic Diffusion and Cluster Pollution in NGC 6752 and M4

   Författare :Pieter Gruyters; Andreas Korn; Piercarlo Bonifacio; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; stars: abundances – stars: atmospheres – stars: fundamental parameters – globular clusters: individual: NGC 6752 and M4 – techniques: spectroscopic; Astronomy with specialization in Astrophysics; Astronomi med intiktning mot astrofysik;

   Sammanfattning : Through the cosmic matter cycle, the chemical evolution of the Milky Way is imprinted in the elemental abundance patterns of late-type stars (spectral types F to K). Due to their long lifetimes ( 1 Hubble time), these stars are of particular importance when it comes to studying the build-up of elements during the early times of our Galaxy. LÄS MER

7. 15. Young Stellar Clumps and Clusters in the Local Universe

   Författare :Matteo Messa; Göran Östlin; Angela Adamo; Petri Väisänen; Stockholms universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Astronomy; astronomi;

   Sammanfattning : The thesis introduces the process of star formation at the scale of galaxies, where a turbulent--dominated interstellar medium (ISM) can locally collapse under self-gravity. This collapse results in a star formation process which is hierarchical both in space and time. LÄS MER