Searching for the origin of metals in galaxies small and large

Supervisor: Dr. Ryan Leaman

Contact information: ryan.leaman@univie.ac.at

Co-supervisors: Dr. Prashin Jethwa

Expected duration: 9 months

Project description & Goals:

The elements we measure from the spectra of stars are produced in several energetic nucleosynthetic sites, from supernovae, to winds from pulsating stars, to rare mergers of neutron stars.  These events produce different mixtures of elements, occur with different frequencies and have different spatial distributions.  Understanding these factors offers a way to peer into a galaxy’s past using present-day observations.  This is particularly challenging in the smallest dwarf galaxies which are known to form rapidly, and often show peculiar chemical signatures indicating inhomogeneous enrichment.  To tackle this exciting problem we are interested in working with a student who will use a novel statistical chemical evolution model together with newly made observations of multi-element abundances in nearby galaxies to recover the spatial clustering and inferred frequency of these nucleosynthetic events.  This would offer one of the first looks at how these key enrichment events were responsible for modulating the star formation, abundance gradients, and even dark matter halos of these most extreme low-mass ‘ultra-faint dwarf’ galaxies.  Finally, the same methodology will be applied to galaxies even more massive than our Milky Way – spectroscopically observed with the flagship MUSE instrument on the VLT telescope as part of the TIMER and F3D surveys.  The student would have an opportunity to work with this cutting edge astronomical data as well as extend the analysis on the low mass resolved galaxies to a new mass and data regime.  Together both aspects will provide new insights on how heavy metals are produced and mixed within the complex baryonic structures of galaxies in the early universe.

Working plan & Milestones (including final thesis):

  1. Compiling and analyzing abundance measurements in stars in nearby dwarf galaxies
  2. Computing intrinsic chemical spreads in multi-dimensional abundance space from these data
  3. Introduction to the statistical chemical evolution model (methodology, literature, mock tests)
  4. Assess likely clustering and frequency of key nucleosynthetic sites based on multi-element abundance data, discuss any scalings with host galaxy properties
  5. Familiarization with integrated light spectroscopic data in the TIMER and F3D MUSE surveys.
  6. Apply statistical chemical evolution method to this integrate light data to improve understanding of age dating the stellar light
  7. Write up thesis

Requirements / special skills: Basic (low-level) familiarity with chemical evolution, python (or equivalent IDL, R etc.) coding, statistics would be helpful but can be acquired throughout the project duration.

References:

arXiv:1810.01425,  arxiv.org/abs/1209.4648