Near-field cosmology - tagging the lowest-mass galaxies

Lead Research Organisation: University of Leicester
Department Name: Physics and Astronomy


The formation and evolution of galaxies is a field of paramount interest in contemporary astrophysics. In this context, one key approach to the study of galaxy formation is dubbed 'near-field cosmology', that is the study of resolved stellar populations in nearby systems in and around the Milky Way. These small scale structures in the Local Group may provide some of the most challenging tests of the currently most successful cosmological models for structure formation and evolution in the Universe. This proposal aims at investigating the role of the faintest dwarf galaxies in the formation and evolution of larger galaxies. The last two years alone have seen the discovery of a dozen of these inconspicuous systems. Thus this proposal aims to study their chemical evolution, star formation histories and their dynamical properties from stellar spectroscopy. These galaxies are nowadays believed to be the fundamental building blocks of large galaxies, although this view is still controversial, as many of their properties are at variance with the stars in the Milky Way. In this work I will focus on the most recently discovered galaxies, which are the faintest, least massive and most metal poor galaxies known to date and still poorly understood. I will achieve these aims by performing chemical element abundance analyses from high-resolution spectroscopy, where I will measure abundances relative to metal poor reference stars. This will be complemented with wide-field photometry and especially medium-resolution spectroscopy. This combination will enable me to efficiently determine these galaxies' spatially resolved star formation and their enrichment histories, which then can be compared to the components of the Galaxy to understand the extent to which these small systems contributed to the build-up of the larger galaxies. The dwarf galaxies, in particular the dwarf spheroidals, are likely highly dark matter dominated systems. By investigating their kinematic properties, which I determine from radial velocity measurements from medium-resolution spectra and subsequent dynamical modeling, I can determine the galaxies' mass and density profiles, estimate their dark matter content and thus place important constraints on the properties of this evasive constituent of the Universe.


10 25 50
Description Gained insight into the distribution and nature of dark matter.
Advances in understanding the chemical evolution of the Milky Way.
Exploitation Route Data disseminated in many publications since then have been used and cited by colleagues.
Sectors Other

Description Used in public talks and press releases.
First Year Of Impact 2009
Sector Education
Impact Types Cultural

Description Constraining the formation of the Galactic bulge from the abundances and kinematics of its constituent stars
Amount £2,700 (GBP)
Organisation The Royal Society 
Sector Academic/University
Country United Kingdom
Start 06/2010 
End 07/2010
Description BRAVA 
Organisation University of California, Los Angeles (UCLA)
Department Physics and Astronomy
Country United States 
Sector Academic/University 
PI Contribution Metallicity measurements of 5000 stars, a new metallicity distribution for the bulge.
Collaborator Contribution Access to full BRAVA data set
Impact Publication in preparation; results were presented on conferences and seminars.
Start Year 2008
Description Carnegie Observatories 
Organisation Carnegie Institution for Science (CIS)
Department Observatories of the Carnegie Institution Washington
Country United States 
Sector Academic/University 
PI Contribution Abundance analyses in globular clusters.
Collaborator Contribution Telescope access (Magellan) and expertise on abundance analyses.
Impact 1 paper published; 1 paper in preparation.
Start Year 2008
Description M31 press release 
Form Of Engagement Activity A press release, press conference or response to a media enquiry/interview
Part Of Official Scheme? No
Primary Audience Media (as a channel to the public)
Results and Impact Publication was used as a press release and posted on all participating Universities' web pages.

Year(s) Of Engagement Activity 2010
Description Physik Journal 
Form Of Engagement Activity A press release, press conference or response to a media enquiry/interview
Part Of Official Scheme? Yes
Primary Audience Public/other audiences
Results and Impact Publication of review article in a German popular science (physics) magazine. Physik Journal is the highest-issue magazine of its kind in Germany (55000 subscriptions).

Received emails from interested readers about more details.
Year(s) Of Engagement Activity 2010