From: Lifan Wang (lifan@panisse.lbl.gov)
Date: Sun Mar 28 2004 - 18:28:38 PST
Rob,
I am sure your numbers are right. I just did a quick check for SN
1996X and 1994D. Here are what I got:
jday R I R-I
190.70 13.23 13.43 -0.20
Tmax = 191.016 -0.22 (my l.c. fit)
191.80 13.18 13.45 -0.27
192.40 13.18
192.80 13.17 13.49 -0.32
193.40 13.18 13.59 -0.41
jday R I R-I
9432.98 11.95 12.24 -0.26
Tmax = 9433.00 -0.26 (my l.c. fit)
9433.70 11.89 12.24 -0.35
9433.75 11.97 12.23 -0.26
9433.90 11.93 12.25 -0.32
In both cases I do not see how it can be up to -0.4 (For 96X, apparently
we have adopted a different date of Bmax). Another z~0 SN in your list
is
95D which you give a color of -0.27 at day -0.2, and my l.c. fit gives
-0.24 with Tmax = 9769.2581.
Most of the SN in your list are at z > 0.01, which direction will
your K-correction change those colors ? Bluer or redder ?
Even if I adopt the bluer color you are using, it is unlikely that
difference will explain the rather large differences in K-corrections.
The color dependence is not steep enough to account for the differences.
The major difference must lie with the wiggles in the template which is
easily 20-30% large at around 7000A.
Cheers,
Lifan
On Sun, 28 Mar 2004, Robert A. Knop Jr. wrote:
> On Sun, Mar 28, 2004 at 04:37:54PM -0800, Lifan Wang wrote:
>> I do not believe R-I can be anywhere close to -0.4 at optical
>> maximum of a normal SN Ia. My light curve fits show most of the SNe
>> with z
>> < 0.005 show -0.24 at B-max. R-I = -0.4 is beyond reasonable physics.
>
> Here's your problem.
>
> Whatever you believe your understanding of the physics of supernovae
> is, the simple fact is that many supernovae are observed to have
> R-I~-0.4 around maximum. Both Serena and I have seen it. Observations
> are going to trump preconceptions about what the physics ought to be
> every time.
>
> Here are some of the colors I have (note that some of these suffer a
> little host galaxy extinction, too!)
>
> SN stretch epoch color (R-I)
> --------------------------------------
> 1994M 0.887 3.3 -0.43 +- 0.04
> 1994S 1.035 0.9 -0.49 +- 0.06
> 1994ae 1.010 -0.4 -0.42 +- 0.04
> 1994ae 1.010 0.6 -0.45 +- 0.04
> 1995D 1.118 -1.0 -0.30 +- 0.05
> 1995D 1.118 -0.2 -0.27 +- 0.07
> 1995D 1.118 1.7 -0.38 +- 0.06
> 1995al 1.084 0.5 -0.35 +- 0.06
> 1995al 1.084 1.4 -0.35 +- 0.08
> 1995ac 1.090 -2.5 -0.21 +- 0.04
> 1995ac 1.090 0.0 -0.29 +- 0.05
> 1995bd 1.040 0.3 -0.35 +- 0.04
> 1995bd 1.040 1.2 -0.42 +- 0.05
> 1996X 0.901 0.2 -0.32 +- 0.03
> 1996X 0.901 1.3 -0.37 +- 0.04
> 1996bl 1.033 -1.6 -0.23 +- 0.04
> 1996bo 0.841 -1.6 -0.34 +- 0.01
> 1996bo 0.841 0.7 -0.31 +- 0.01
> 1992al 0.958 1.7 -0.40 +- 0.04
> 1992bc 1.081 1.4 -0.50 +- 0.03
> 1992bo 0.737 0.0 -0.27 +- 0.04
> 1992bo 0.737 1.3 -0.32 +- 0.05
>
> -Rob
>
>
-- Lifan Wang (510) 495 2733 (o) (510) 704 0119 (h)
This archive was generated by hypermail 2.1.4 : Mon Mar 29 2004 - 17:32:59 PST