Summer2009»Project Descriptions

Project Descriptions

This page contains descriptions of projects planned for summer 2009. Students will work with a mentor from the faculty or postdoctoral researchers. The descriptions here vary in terms of specification -- project details are subject to change.

Also see descriptions of past summer projects.

Sept 10, 2009 -- The summer program is over. See the seminars page for student descriptions of their work.

2009 Summer Undergraduate Research Projects

  1. Cosmic Microwave Background (CMB) Analysis (Mentors: Toby Marriage and Sudeep Das, Students: Sean Frazier and Nick Hand)
    The Atacama Cosmology Telescope (ACT) is a 6m telescope which we installed in the Andes of northern Chile (in the Atacama Desert) in the Spring of 2007. Since then, ACT has been surveying approximately 1000 square degrees of sky at millimeter wavelengths. At these wavelengths ACT images temperature fluctuations in the very early universe (primordial CMB) as well as galaxies (through emission) and galaxy clusters (through the Sunyaev-Zel'dovich Effect). The proposed summer research will involve one student in the analysis of ACT data, most likely related to galaxies and galaxy clusters. The student will work in the context of the larger "Southern Cosmology" collaboration which includes colleagues and other surveys (e.g., the Blanco Cosmology Survey) based in Chile and South Africa.
  2. Radiative Transfer Modeling of Evolved Star Dusty Nebulae
    (Mentor: Jason Nordhaus, Student: Dale Mack)
    For low-mass stars (< 8 M_sun), the late stages of post-MS evolution are characterized by the development of strong winds and efficient dust formation. During the post-Asymptotic Giant Branch, mass loss enshrouds the star in a dusty, reflection nebulae. The post-AGB phase is short (< 10^3 years) and particularly important as it marks the transition from the spherical, mass losing AGB phase to the highly aspherical outflow phase characteristic of planetary nebulae. The physical mechanism responsible for the transition remains unidentified.

    This project aims to characterize the morphology, composition and properties of a sample of post-AGB stars observed with the Spitzer Space Telescope. The student will employ two radiative transfer codes (one corresponding to a spherical shell geometry and the other to a disk geometry) to fit the observed spectral energy distributions. Through detailed fitting of the IRS spectra and broad-band SED, properties of the dust, including composition and distribution, will be constrained. This project involves a complementary blend of theoretical, observational and computational techniques.
  3. Galaxy Formation (Mentors: Renyue Cen and Ryan Joung, Students: Chris Cleveland and Aaron Bray)
    A student (or students) will work in the general area of galaxy formation (using AMR hydrodynamical simulations). We will look at various physical properties of simulated galaxies, including gas content, stellar properties, environments, etc.
  4. Stellar Chemical Compositions: Clues to the Building Blocks of the Universe (Mentor: Inese Ivans, Student: Sarah Wellons)
    Astronomers are on the verge of discovering the First Galaxies and First Stars the Universe made long ago when it was very young. But, these observations need to be tied to what we know about the local Universe and our Galaxy The stars we observe today contain within them the chemical signatures (the "fossil imprints") of stars now long dead. The ashes of previous generations of stars go into the material out of which subsequent generations are born, and so can be used in studies of stellar and Galactic archaeology. Carbon, calcium, iron, gold, platinum, uranium ... these are only a few of the elements that have been applied to a range of questions, from stellar nucleosynthesis to the physics of supernovae to Near Field Cosmology. The student's role in this effort will be to participate in the gathering and analysis of high resolution stellar spectroscopic data. The analyses will be focused on deriving detailed chemical compositions using existing software (mostly written in Fortran and IDL). Aspects of the work will be far more interesting if the student has some programming skills. Accordingly, experience with IRAF would make the summer experience that much more profitable.
  5. The Structural Properties of High-Redshift Galaxies
    (Mentors: Mariska Kriek & Jenny Greene, Student: Michael Gordon)
    Although massive galaxies already existed in the early universe, their structural properties are very different from those in the local universe. Massive, quiescent galaxies in the distant universe have stellar densities that are 2 orders of magnitude higher than found for local early-type galaxies of similar mass. This new result implies that apparently dead distant galaxies do not passively evolve into their local analogs. On the contrary massive star-forming galaxies seem to have irregular morphologies in the early universe, while they are spiral galaxies at the present day. To better understand how these distant galaxies evolve into the galaxies we find in the local universe, we need to know how they are built up. Do they have composite stellar populations, for example an old central core, with younger surrounding starburst regions? Or the other way around? How does this effect the size and morphology measurements. How different are distant star-forming galaxies from distant quiescent galaxies? Do they both have a similar underlying old population, and thus is there a simple evolutionary link, or are they completely different populations of galaxies? In this project we aim to address these question by making artificial galaxies of different stellar populations, extracting the integrated properties, and comparing these with observations.

# Gravitational Lensing of the Cosmic Microwave Background a.k.a. CMB Lensing (Mentor: Sudeep Das, Student: Nick Hand)

We have reasons to believe that the distribution of matter in the very early universe was uniform. As time passed, tiny fluctuations in the (dark) matter density grew into large and interconnected structures, aptly called the cosmic web. This animation by Andrey Kravtsov beautifully illustrates the idea.

You can think of the Cosmic Microwave Background (CMB) as a source of light behind all these structures. As these CMB photons propagated from the very early universe, they passed through or near these gradually growing massive structures which exerted gravitational pull on the photons and deflected their paths. We are picking up these photons today with telescopes like the Atacama Cosmology Telescope (ACT), which is operational in Chile now. It is easy to infer then, that the map of the hot and cold spots on the CMB that we see with our telescopes, is a distorted version of the original image due to these deflections. This phenomenon is called CMB Lensing. Here is a small section of a simulated CMB sky and shows how lensing distorts the original image. Our project will focus on how we can detect these distortions and use them to draw important conclusions about the contents and history of the universe. There will also be the exciting possibility of applying our methods to the (real ! ) data from ACT.

  1. Galaxy Cluster Studies with SALT and ACT (Mentor: Caroline Zunckel, Student: Hassen Yesuf)
    Being the largest collapsed objects in the Universe, galaxy clusters provide a fair sample of the matter content as well as a probe of the growth of large-scale structure. One way in which they are identified is through the Sunyaev-Zeldovich (SZ) decrement that they produce in the Cosmic Microwave Background. The relationships between cluster masses and their other observables are a rich source of cosmological information. However a major source of uncertainty in the mass estimates is the cluster's dynamical state. Mass estimates rely on the assumption that hydrodynamic equilibrium has been established between the cluster gas and dark matter. It is possible to use optical images of clusters to check whether they are in fact 'relaxed'. The proposed summer research will involve the use of the 11m Southern African Large Telescope (SALT) in South Africa, to collect follow-up spectra of a subset of clusters that have been detected from their SZ signal using ACT. The student will compile and implement a set of tests on the optical images in order to classify the clusters' dynamical states. This project will form part of the "Southern Cosmology" collaboration and will involve some time being spent working in South Africa with members of this consortium.
  2. Accelerating Particle Acceleration in Shocks (Mentor: Anatoly Spitkovsky and Lorenzo Sironi, Student: Michael Jimenez )
  3. Looking for Low Luminosity Galaxies Among the SDSS Sky Fibers (Mentor: Michael Strauss, Student: Margaret Shaw)
  4. CMB and Topology of the Universe (Mentor: Amir Hajian, Student: Amelia Yzaguirre)
  5. CMB Analysis: tSZ Effect (Mentor: Amir Hajian, Student: Solomon Abiola)
  6. On the Small-Scale Distribution of Galactic Dust (Mentor: Aurelien Fraisse, Student: Katie Silverio)