helio vs. cmb redshifts

From: Alex Conley (aconley@panisse.lbl.gov)
Date: Sun Mar 16 2003 - 11:11:24 PST

  • Next message: Robert A. Knop Jr.: "Re: helio vs. cmb redshifts"

    I was thinking about how you are using cmb vs. heliocentric redshifts,
    and I think you are doing it wrong in snminuit. You definitely want
    the K-corrections to be done heliocentrically, but the stretch
    fits should be done in the CMB frame. Really, the time axis
    should be corrected for the shift from the Heliocentric to the CMB frame,
    and then the fit should be done to what the lc would have looked like
    in the CMB frame, but we're not set up for that. The problem is that
    you fit the stretch heliocentrically, but then make use of it in the
    CMB frame to fit cosmology. So your correction factor slope alpha is
    being fit in a frame that is not the frame that the thing it is using
    was fit in, which seems wrong.

    Fortunately, this is a pretty pedantic issue. I can't imagine it makes
    much of a difference in the end, especially if you are assuming
    peculiar velocity errors on z.

    Alex

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