Near-field cosmology - tagging the lowest-mass galaxies
Lead Research Organisation:
University of Leicester
Department Name: Physics and Astronomy
Abstract
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.
People |
ORCID iD |
Andreas Koch (Principal Investigator / Fellow) |
Publications
Donato F
(2009)
A constant dark matter halo surface density in galaxies
in Monthly Notices of the Royal Astronomical Society
Glatt K
(2009)
STRUCTURAL PARAMETERS OF SEVEN SMALL MAGELLANIC CLOUD INTERMEDIATE-AGE AND OLD STAR CLUSTERS
in The Astronomical Journal
Quinn D
(2009)
On the reported death of the MACHO era
in Monthly Notices of the Royal Astronomical Society: Letters
Howard C
(2009)
KINEMATICS AT THE EDGE OF THE GALACTIC BULGE: EVIDENCE FOR CYLINDRICAL ROTATION
in The Astrophysical Journal
Adén D
(2009)
A photometric and spectroscopic study of the new dwarf spheroidal galaxy in Hercules Metallicity, velocities, and a clean list of RGB members
in Astronomy & Astrophysics
Koch A
(2009)
A SPECTROSCOPIC CONFIRMATION OF THE BOOTES II DWARF SPHEROIDAL
in The Astrophysical Journal
Adén D
(2009)
A NEW LOW MASS FOR THE HERCULES dSph: THE END OF A COMMON MASS SCALE FOR THE DWARFS?
in The Astrophysical Journal
Koch A
(2009)
Complexity in small-scale dwarf spheroidal galaxies - Ludwig Biermann Award Lecture 2008
in Astronomische Nachrichten
Koch A
(2009)
All quiet in the outer halo: chemical abundances in the globular cluster Pal 3
in Astronomy & Astrophysics
Koch A
(2010)
A DIFFERENTIAL CHEMICAL ABUNDANCE SCALE FOR THE GLOBULAR CLUSTER M5
in The Astronomical Journal
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 | Charity/Non Profit |
Country | United Kingdom |
Start | 05/2010 |
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. n/a |
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 |