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| Predoctoral Projects, 2008 | ||
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Project Title: Global Properties of Nearby Galaxies in the Infrared Project Advisor: Dr. Michael A. Pahre Background: The launch of the Spitzer Space Telescope has revolutionized infrared (IR) astronomy for studying the properties of the local universe. Spitzer has produced many stunning IR images of nearby galaxies since its first early release observations in December 2003. Observations made since then continue to provide countless surprises, even for galaxies we thought we "knew" already! IR techniques produce clear spectral separation of different galaxy astrophysical processes (emission from starlight, cold/warm/hot dust, PAH grains, AGN). Spitzer's angular resolution and sensitivity allow for deep imaging out to the edge of the galaxy. The observatories efficiency means that large galaxy samples can be studied, as well as complete images of large, nearby galaxies (M31, M33, M81). Scientific Questions: What are the fundamental astrophysical processes that lie at the heart of a galaxy classification scheme? We are investigating several key parameters: ratio of dust mass to stellar mass, stellar bulge-to-disk-ratio, age of the stellar population, bar strength/torque, star formation rate (global and local), etc. How can these processes best be identified, separated, and characterized? We are finding that various IR wavelengths provide powerful tools to cleanly separate out many of the fundamental astrophysical processes.What is the fraction of galaxies with an AGN, and of what types? We have only begun this part of the study, but expect it to be an important one in the future because of the clear IR spectral signature of an AGN. Scientific Methodology: This project utilizes large surveys of nearby galaxies in the IR--much of which was obtained under Giovanni Fazio's (SAO) guaranteed time and is hence proprietary. Comparison of IR emission properties with those at other wavelengths (X-ray, UV, optical, sub-mm) primarily draws upon existing data archives from other space missions (Chandra, HST), but also additional observations from the ground (Halpha, near-IR from Mt. Hopkins; sub-mm with the SMA). Several other SAO researchers (Dr. Giovanni Fazio, Dr. Matt Ashby, Dr. Steve Willner) add additional expertise on various aspects of the overall project. Some approaches we are currently investigating: (1) creating an IR "Hubble Atlas of Galaxies," as well as a new, IR galaxy classification scheme; (2) comparing the star-formation rate, both locally and globally, as measured at UV, Halpha, and IR (PAH, warm dust, and cold dust); (3) studying the galaxy bar properties (torque, stellar mass); (4) contrasting IR properties among the wide-ranging class of irregular galaxies. Other links related to this project.
Recent publications related to this project
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