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Title: Empirical population synthesis: New directions

Miscellaneous ·
OSTI ID:5258918

Empirical population synthesis (EPS) is a technique to decompose composite galaxy stellar populations into their component populations. From this decomposition, a stellar luminosity function is derived and used to analyze the star-formation history of the observed galaxy population. In this study, EPS is used to investigate the nuclear stellar populations of the spiral galaxies NGC 1219, NGC 3177, NGC 3512, and NGC 4032. An EPS algorithm based on linear combinations of stellar spectra is implemented and tested. A maximum entropy variant is also tested. The effects of stellar-spectra degeneracy on EPS solutions are investigated. Stellar degeneracy is quantified using linear correlation analysis. A Monte Carlo technique is implemented to estimate the uncertainties of the derived individual stellar components. Medium-resolution (12{angstrom}) data spanning 3500-9000{angstrom} were acquired for the four galaxies above. A stellar spectral library with good luminosity and temperature discrimination was also constructed. Using these data and EPS, luminosity functions are derived for the observed spiral nuclei. Component uncertainties are calculated and the effects of uncertain continuum determination on these uncertainties is discussed. Data for the irregular galaxies NGC 1569 and NGC 4449 were also acquired but detailed luminosity functions are not derived. Conclusions from both the spiral and irregular galaxies are discussed.

Research Organization:
Michigan Univ., Ann Arbor, MI (United States)
OSTI ID:
5258918
Resource Relation:
Other Information: Thesis (Ph.D)
Country of Publication:
United States
Language:
English