NOAO >   Observing Info >   Approved Programs >   2012B-0515

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Proposal Information for 2012B-0515


PI: Dennis Zaritsky, University of Arizona, dennis.zaritsky@gmail.com
Address: Astronomy Department, 933 N. Cherry Ave., Tucson, AZ 85721, USA

CoI: Ann Zabludoff, University of Arizona
CoI: Anthony Gonzalez, University of Florida

Title: Searching for Systematic Effects in SNe Ia Distances

Abstract: SN Ia distances are critical for extragalactic astronomy and future efforts to constrain cosmological models will be limited by potential systematic errors in those distances. The magnitude of such errors can be constrained by examining whether residuals from a distance-dependent relation, such as the Hubble diagram, correlate with potential error sources, such as host galaxy metallicity or mean stellar age. Unfortunately, the Hubble diagram test is compromised for local galaxies by the effect of peculiar velocities and is difficult to carry out in distant galaxies, where measuring host galaxy properties becomes more challenging. Our new approach employs the distance-dependent, galaxy scaling relation, the Fundamental Manifold (an analog of the Fundamental Plane). Because this relation works for the full range of galaxy types and masses, we can study the residuals about this relation for large samples of nearby galaxies (< 200 Mpc) with existing Ia distances and span as large a range in host galaxy metallicity and mean stellar age as possible. Here we propose to increase the sample size over our initial pilot study by a factor of 5 to quantify more precisely known systematic effects, such as the dependence of Ia distances on host galaxy metallicity, and test for unknown ones.


National Optical Astronomy Observatory, 950 North Cherry Avenue, P.O. Box 26732, Tucson, Arizona 85726, Phone: (520) 318-8000, Fax: (520) 318-8360



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