SIDNEY M. LOWER

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MY RESEARCH

My research interests are broadly described as galaxy formation and evolution. Most of my undergraduate research focused on a subset of galaxies known as sub-mm galaxies, studying their properties, learning a lot about SED modeling, and how to think like a scientist. My current research is built upon the tools and techniques I learned then, and I am now working to improve our understanding of SED modeling and the assumptions we make when asking a simple question like “How do we measure the stellar mass of this galaxy?” I work with Dr. Desika Narayanan and utilize Hipergator, University of Florida’s supercomputer cluster, using cosmological simulations to push our understanding of galaxy formation and evolution.

Projects

SED Modeling

Optical/ultraviolet spectral energy distribution fitting of galaxies is a well established technique to determine fundamental physical properties such as the star formation rate and stellar mass. Of the many assumptions that go into this technique, the star formation history and dust attenuation law dominate the uncertainty. Classically, SFHs are modeled via parameterized functional forms, such as the delayed-tau model. However, these forms are unlikely to capture the true diversity of galaxy SFHs in a hierarchical Universe and may impose systematics on measured results. Recent developments in non-parametric SFH models in SED fitting techniques have shown promise in marginalizing over some of these uncertainties. I am examining the efficacy of non-parametric SFHs in SED modeling by ground-truthing them against high-resolution cosmological hydrodynamic galaxy formation simulations. These new SFH models impact our understanding of both the evolution of cosmic stellar mass functions, as well as the as-yet unexplained historical mismatch between the theoretical and observed SFR-M* relation in galaxies. I also plan to apply an analogous non-parametric variable dust attenuation model for SED fitting techniques, forging a path forward for a next generation SED modeling code that can successfully estimate the fundamental physical properties of any galaxy.

Infrared and Radio Properties of High Redshift Dusty Star Forming Galaxies

Previously, my projects were centered around galaxies discovered with the South Pole Telescope (SPT). These galaxies comprise a catalog of systematically selected gravitationally lensed dusty galaxies. Gravitational lensing results from massive foreground galaxies or galaxy clusters bending light emitted from background galaxies towards Earth, magnifying the brightness which allows fainter and higher redshift galaxies to be seen. As a consequence, these sources are selected to be at high redshift and are very luminous at sub-mm wavelengths. My work broadly involved characterizing these sources in terms of their physical properties. I estimated the number density of the SPT source catalog, fit modified blackbody SEDs to their photometry to estimate dust properties, and analyzed radio data from ATCA to determine the far-infrared radio correlation at high redshift.

Publications

Press