Re: E(B-V) vs stretch

From: Greg Aldering (aldering@panisse.lbl.gov)
Date: Fri May 16 2003 - 13:37:32 PDT

  • Next message: Robert A. Knop Jr.: "Re: E(B-V) vs stretch"

    Hi Rob,

    I agree that the ellipticals look as good as anything on the E(B-V)
    versus stretch plot.

    On Fri, 16 May 2003, Robert A. Knop Jr. wrote:

    > On Fri, May 16, 2003 at 01:20:04PM -0700, Greg Aldering wrote:
    >
    > > Ok, grabbed b-v_snelist.lis from your webpage, and plotted the
    > > residuals (which I assumed were in the last column) vs stretch for SNe
    > > within 3 stretch-corrected days of max. What I see is that the
    > > residuals of the ridgeline of points misses zero by about 0.02-0.03 mag.
    > > There may be some higher-order effect as well, but that is harder
    > > to say with confidence.
    >
    > Last column is E(B-V), yes.
    >
    > What do you mean when you say the residual of the ridgeline of points is
    > missing? What is the diagnostic that you're using?

    I am ploting E(B-V) versus stretch for SNe within 3 stretch-corrected
    days of max. Them I am *visually* identifying clumps of SNe which seem
    to have similar E(B-V) at similar stretches, or which seem to fit-in with
    the trends those clumps exhibit.

    After the snap meeting I can try to send you a plot.
    Or you can run this snippet of IDL:

    readcol,'b-v_snelist.lis',name,s,date,bmv,errbmv,resid,format='(a,f,f,f,x,f,f)'
    w = where(abs(date/s) lt 3,nw)
    plot,s[w],resid[w],psym=4,yrange=[-0.2,0.2]
    oploterr,s[w],resid[w],errbmv[w]

    > Of the HST SNe in the paper, when the reddest ones are thrown out (92ag
    > and 93ag), the vairance weighted mean E(B-V) (based now on lightcurve
    > fits) comes out at -0.004+-0.004. If the line moves any to the redder,
    > we will have the "too blue Hamuy" supernovae problem again.

    Right, I appreciate that is is a problem. I wonder why it is not apparent
    in the plot (above) that I am making.

    > I've attached a plot of E(B-V) vs. s. Again, these E(B-V) are the
    > results of the snminuit fits, and thus not exactly the same thing as the
    > numbers from b-v_snelist.lis (which is the E(B-V) value at the given day
    > from the color curve, not from any sort of lightcurve). The ellipticals
    > (the ones from the list you sent me) are the black points. This
    > distribution looks pretty good to me.

    Yes, this looks pretty good.



    This archive was generated by hypermail 2.1.4 : Fri May 16 2003 - 13:37:34 PDT