Star-forming Dwarf Galaxies: Internal motions and evolution
2012 (English)Doctoral thesis, comprehensive summary (Other academic)
The study of dwarf galaxies is important in order to better understand the physics of the young universe and how larger galaxies form and evolve. In this work we focus on Blue Compact Galaxies (BCGs) which havemuch enhanced star formation (starbursts), causing blue colours and strong emission line spectra.
Investigating of the inner motions of BCGs provides a means for determining masses and understanding what triggered the current starburst. We have used the Very Large Telescope to perform challenging observations of the stellar motions in several BCGs, as seen in the near-infrared Ca-triplet absorption lines. By comparing these to the kinematics of the ionized interstellar medium, we were able to look into the role of feeback from stellar winds and supernova explosions, as well as further strengthen the notion that the merging of galaxies plays an important role.
Spatially resolved spectroscopy can yield information about the 3D-structure of galaxies. We have used a Fabry-Perot interferometer to study the kinematics of the interstellar medium in two samples of galaxies, each containing about twenty objects. We find strong indications for ongoing galaxy mergers that correlate well with the strength of the star-formation activity. Furthermore, by estimating dynamical masses, BCGs are shown to be on average not dynamically supported by rotation.
In addition, we have used data from the Sloan Digital Sky Survey to study the frequency of starbursts in the local universe and the connection to their descendants. We selected starbursts by the strength of emission in H-alpha, the first Balmer recombination line, and post-starbursts by the strength of absorption in H-delta. These are indicators of currently ongoing and recent, on the order of 100 Myr, star-formation, respectively. By modelling the stellar populations we derive ages and masses and can establish a link between starbursts and postbursts in a time sequence. We find that starbursts are active on a 100 Myr timescale but are rare objects in the local universe.
Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2012. , 27 p.
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 977
Galaxy, Galaxies, Dynamics, Kinematics, Starburst, Dwarf Galaxies, Blue Compact Galaxies, Star Formation, Galaxy mergers, 3D-Spectroscopy, Spectroscopy
Astronomy, Astrophysics and Cosmology
Research subject Astronomy
IdentifiersURN: urn:nbn:se:uu:diva-181481ISBN: 978-91-554-8483-5OAI: oai:DiVA.org:uu-181481DiVA: diva2:557091
2012-11-12, Häggsalen, Ångströmlaboratoriet, Lägerhyddsvägen 1, Uppsala, 10:15 (English)
Lee, Janice, Dr.
Bergvall, Nils, Prof.
List of papers