abstract

From: Kyle Dawson (kdawson@lbl.gov)
Date: Wed Oct 19 2005 - 17:06:06 PDT

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    Decelerating and Dustfree: Targeting SNe in Very High Redshift Galaxy
    Clusters

    We present a novel approach to obtaining Type Ia supernovae (SNe Ia) at
    very high redshifts (z>1). In a 219 orbit cycle 14 program, we are
    using the Advanced Camera for Surveys (ACS) and NICMOS on the Hubble
    Space Telescope (HST) to repeatedly observe massive galaxy clusters at
    z>1 to find and follow SNe. Clusters of galaxies are known to be
    dominated by nearly dust-free early type galaxies. SNe discovered in
    these glaxies are expected to have negligible dust extinction, the
    largest source of both statistical and systematic uncertainty in SNe
    derived distances. In addition, galaxy clusters contain a population of
    early type galaxies at a density approximately five times that in the
    high redshift field, leading to a much higher rate of detection of SNe
    Ia in this well-understood host environment. With 20 scheduled
    half-nights on the Subaru telecope as well as multiple nights on the
    Keck telescope, we are obtaining spectroscopic confirmation and redshift
    of newly discovered SNe and their hosts. This data will significantly
    improve supernova constraints of dark energy both in terms of
    statistical uncertainty, and perhaps more importantly, of systematic
    uncertainty. This sample of more than 20 galaxy clusters is also being
    studied for weak lensing, galaxy morphology, and color-magnitude
    relationship, as part of an entire program of cluster studies.

    This work was supported in part by the Office of Science, US DoE, under
    contract DE-AC03-76F00098 and in part by NASA through grants associated
    with HST-GO-10496.



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