S02-002 and spectroscopy web page

From: Andy Howell (DAHowell@lbl.gov)
Date: Sat Apr 13 2002 - 18:37:21 PDT

  • Next message: Saul Perlmutter: "S02-002 may not be too bright for 1.07 redshift..."

    SCPers,
    I have started running the spectroscopy from the supernovae from this
    search through my automated matching program. I am posting the results
    on the SCP spectroscopy web page:
    http://panisse.lbl.gov/collab/data/spec/

    My program has 10 template galaxy spectra, and about a hundred template
    SNe spectra.
    I simultaneously subtract galaxy light and fit templates until a minimum
    in residuals is achived. This is done for a range of redshifts. When
    we have a spectrum of the host galaxy, I use that rather than a template.

    For S02-002 the results are interesting. I tried redshifts from 0.2 to
    1.2. The best fit is to a Type Ia at z=1.08 (SN 1990N at -7d) just as
    Chris found by eye. While this solution is best, it is far from unique.
    Several SNe match in the z=0.57 range (esp. Ib/c's), and several match
    in the z=0.83 range. (See links at the web page for some representative
    examples).

    Keep in mind that my program does not cover all of parameter space -- I
    have no hypernovae spectra for example.

    So even though the answers run all over the place for this SN,
    quantitatively, and by eye, the matches at z=1.08 seem to be better than
    all of the rest. As Chris pointed out, this is problematic because the
    SN seems too bright to be at that redshift.

    I think we should consider the possibility that this SN is
    gravitationally lensed. There are many other possible explanations, but
    given the data we have I can't be sure what is going on.
    We really need more spectra. I recommend taking spectra with Keck as
    soon as possible.

    -Andy

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