AAS 197, January 2001
Session 76. Galaxy Evolution I
Display, Wednesday, January 10, 2001, 9:30am-7:00pm, Exhibit Hall

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[76.05] Dissecting Nearby Galaxies

M Takamiya, M Chun (Gemini Observatory)

To date, there is little physical understanding of what drives the morphologies of galaxies. It is difficult to determine unambigously the morphological types of galaxies at high redshifts. We have begun a study to explore the underlying physical conditions in galaxies and to measure their structure in a quantitative manner. We present preliminary results of an imaging and 3-D spectroscopic program of nearby starburst galaxies. Our goal is to link morphological features such as the lumpiness and the concentration index to physical processes.

A number of algorithms to classify galaxies objectively have been introduced(c.f. Abraham et al 1996, Takamiya 1999). Here we present two parameters that characterize the structure of galaxies: the metric radius of the galaxy and the power at high spatial frequencies. These parameters are measured in galaxy images at similar rest-frame energies.

The parameter \chi that characterizes the degree of lumpiness in the disks of galaxies is measured with a simple method based on surface photometry in one band, the size of the star-forming regions, and the intensity profile of the galaxy. In nearby galaxies, the lumpiness correlates with global parameters such as the integrated optical colors (B-V) and H-\alpha EW.

To study the nature of the giant starburst galaxies in more detail, we have started a spectroscopic survey of nearby galaxies in 3-D. Using DensePak at WIYN (KPNO), we are able to map the SED across the galaxy distinguishing already variations in the rates of star formation and dust extinction within 1-kpc scales. We have two specific goals in mind. One is to produce SED and star formation history maps of individual galaxies as input for realistic simulations of high-z galaxies. Second, to determine the amount of extinction from the 3-D spectra and determine an internal extinction vs. structural parameter relation for corrections to SNe luminosities.

The author(s) of this abstract have provided an email address for comments about the abstract: mtakamiya@gemini.edu

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