Below is a list of currently available student projects. For students new to the group, I ask them to complete problem #3 from Homework set #2. Working on this problem will give you much of the language used in the projects below.
SAGA project: Reduce DECam Imaging of Milky Way analog systems
The SAGA project current targets candidate dwarf galaxies using SDSS. However, SDSS has known incompleteness at low surface brightnesses. We have obtained data for 7 Milky Way analog systems with DECam. This project will entail reducing DECam imaging, creating object catalogs and comparing to SDSS in order to quantify improvements in both low surface brightness objects and measured properties.
- Paper quantifying low surface brightness galaxies (poorly written, but good methods paper: http://arxiv.org/abs/1407.0307
SAGA Project: Modeling Milky Way dwarf galaxies in Deep Imaging data
In searching for dwarf galaxies around distant Milky Ways, is SDSS imaging data sufficient to detect the known Milky Way satellites if placed at large distances? This project will start with models of the Milky Way dwarfs, place these artificial galaxies into imaging data and determine if they would be detected with SDSS and/or deeper imaging surveys.
Joint Project with J. Simon (Carnegie): Proper Motions of extremely metal-poor stars
The goal of this project is to determine the Galactic orbits of the most metal-poor stars known (the [Fe/H] < -4) to provide some insight into their origin and there compare to theoretical predictions. While proper motions are listed in standard astrometry catalogs (USNO, UCAC) for many of these objects, errors are very large. Instead, this project aims to construct a new proper motion solution based on DSS and SDSS images.
Detectability of Black Holes in Dwarf Galaxies (as of 7/2014 still available)
Requires programming, familiarity with spectra: Super massive black holes are throught to exist in most (if not all) galaxies more massive than the Milky Way. It is not clear if less massive galaxies also habor black holes. Using spectra from the SDSS, Reines et al (2013) discovered 150 Active Galactic Nuclei (AGN) in dwarf galaxies based on spectral line ratios. However, this paper did not put quantitative limits on how massive a black hole could have been detected. This project will simulate the SDSS spectra and quantify the detectability of black holes in low mass galaxies.
- Public press release
- Discovery paper: Reines et al
- Characterizing black holes in dwarf galaxies
- WISE catalog search finds low mass AGN
Improving mass measurements of Ultra-Faint Dwarf Galaxies: ML vs. MCMC
Once we identify member stars in a dwarf galaxy, we can use their relative velocities to estimate their total mas. While there are a few codes which use the individual velocities themselves to estimate mass, we usually determine the velocity dispersion and use this to calculate mass. The errors on individual memberships is perilously close to the dispersion itself. That is, if I plot a histogram of velocities, the intrinsic width due to the mass of the galaxy is pretty close to the width of the histogram just based on measurement errors. We’d love to get more accurate errors, but the stars are faint and we are using the biggest telescope available to do this work! We have been using a Maximum Likelihood estimator to determine dispersion, but this assumes that the intrinsic shape is Gaussian. I have also written an Markov Chain Monte Carlo (MCMC) script to estimate this which does not assume Gaussians, but have not had time to properly test this code. The project would be creating fake datasets and testing both algorithms.
Machine Learning to Improve Finding Satellites around Distant Milky Ways
Spectral Data Reduction of Milky Way-Analog Satellite Candidates
We have multifiber spectroscopic data take with the WIYN HYDRA telescope. These data were taken to identify satellites around Milky Way analog galaxies. We have 3 nights of data which need to be reduced and 5 additional nights of observing time (Feb 20-24 and March 3-4). This project will consist of running the data through an existing reduction pipeline, and analyzing the resulting spectra.
Search for Pulsars in Ultra-Faint Galaxies to constrain the IMF
The Ultra-faint galaxies appear to have a more shallow IMF than the Milky Way. What was the shape of the high mass end of the IMF? Massive stars have long since left the main sequence, but the remnants (in the form of neutron stars/pulsars) may be detectable.
- Paper from T. Abel: http://adsabs.harvard.edu/abs/2006MNRAS.372.1540M
- Paper discussion how pulsars are detected with Arecibo: http://arxiv.org/abs/1405.7953