BOSS DR12 survey: Clustering of galaxies and Dark Matter Haloes
Sergio Rodriguez, UAM, Madrid and Cal. Berkeley
BOSS SDSS-III is the largest redshift survey for the large scale structure and a powerful sample for the study of the low redshift Baryonic Acoustic Oscillations. We combine the features of the survey, such as, geometry, angular incompleteness and stellar mass incompleteness, with the BigMultiDark cosmological simulation to do a study of the distribution of galaxies in the dark matter halos. Using this large N-Body simulation and the halo abundance matching technique, we found a remarkably good agreement with the 2-point and 3-point statistics of the data.
New Tools for Galactic Archaeology from the Milky Way
Gail Zasowski, John Hopkins University
One of the critical components for understanding galaxy evolution is understanding the Milky Way Galaxy itself — its detailed structure and chemodynamical properties, as well as fundamental stellar physics, which we can only study in great detail locally. This field is currently undergoing a dramatic expansion towards the kinds of large-scale statistical analyses long used by the extragalactic and other communities, thanks in part to an enormous influx of data from space- and ground-based surveys. I will describe the Milky Way and Local Group in the context of general galaxy evolution and highlight some recent developments in Galactic astrophysics that take advantage of these big data sets and analysis techniques. In particular, I will focus on two diverse approaches: one to characterize the distribution and dynamics of the carbon-rich, dusty diffuse ISM, and one to map the resolved bulk stellar properties of the inner disk and bulge. The rapid progress in these areas promises to continue, with the arrival of data sets from missions like SDSS, Gaia, LSST, and WFIRST.
Extinction mapping with LEGUS
The study of star formation and galaxy evolution in nearby galaxies depends on obtaining accurate stellar photometry in those galaxies. However, dust in the galaxies hinders our ability to obtain accurate stellar photometry, particularly in star-forming galaxies that have the highest concentrations of dust. This proposal presents a thesis project to develop a method for generating extragalactic extinction maps using photometry of massive stars from the Hubble Space Telescope. This photometry spans nearly 50 galaxies observed by the Legacy Extragalactic Ultraviolet Survey (LEGUS). The derived extinction maps can be used to correct other stars and Halpha maps (from the Halpha LEGUS) for extinction, and will be used to constrain changes in the dust-to-gas ratio across the galaxy sample and in different star formation rate, metallicity and morphological environments. Previous studies have found links between galaxy metallicty and the dust-to-gas mass ratio. The relationship between these two quantities can be used to constrain chemical evolution models.
Selected galaxies will also be compared to IR-derived dust maps for comparison to recent M31 results from Dalcanton et al. (2015) which found a minimum factor of 2 inconsistency between their extinction-derived maps and emission-derived maps from Draine et al. (2014).
Asteroseismology of Red Giants: The Detailed Modeling of Red Giants in Eclipsing Binary Systems
Jean McKeever, NMSU
Asteroseismology is an invaluable tool that allows one to peer into the inside of a star and know its fundamental stellar properties with relative ease. There has been much exploration of solar-like oscillations within red giants with recent advances in technology, leading to new innovations in observing. The Kepler mission, with its 4-year observations of a single patch of sky, has opened the floodgates on asteroseismic studies. Binary star systems are also an invaluable tool for their ability to provide independent constraints on fundamental stellar parameters such as mass and radius. The asteroseismic scaling laws link observables in the light curves of stars to the physical parameters in the star, providing a unique tool to study large populations of stars quite easily. In this work we present our 4-year radial velocity observing program to provide accurate dynamical masses for 16 red giants in eclipsing binary systems. From this we find that asteroseismology overestimates the mass and radius of red giants by 15% and 5% respectively. We further attempt to model the pulsations of a few of these stars using stellar evolution and oscillation codes. The goal is to determine which masses are correct and if there is a physical cause for the discrepancy in asteroseismic masses. We find there are many challenges to modeling evolved stars such as red giants and we address a few of the major concerns. These systems are some of the best studied systems to date and further exploration of their asteroseismic mysteries is inevitable.