GCN Circular 2081
Subject
GRB 030329, light curve and SN prediction
Date
2003-04-03T14:10:56Z (22 years ago)
From
Sylvio Klose at TLS Tautenburg <klose@tls-tautenburg.de>
A. Zeh, S. Klose (Thueringer Landessternwarte Tautenburg),
J. Greiner (MPE Garching),
report:
Using the light curves of SN 1998bw (Galama et al. 1998, Nature 395,
670) as a template we have analyzed what color changes are expected to
be seen in the optical transient following GRB 030329 if a supernova
component would appear.
Ingredients:
------------
1) SN 1998bw:
- A_V = 0.20 mag (Woosley, Eastman, & Schmidt 1999, ApJ 516, 792)
- no time delay between the onset of the SN and the onset of the GRB
- A_V(host) = 0.0 mag
2) The host galaxy:
- z = 0.1685 (Greiner et al. 2003, GCN 2020)
- a negligible host flux in BVRI (based on R>22.5; Blake & Bloom 2003,
GCN 2011)
- A_V(Galaxy) at (l, b) = 217.07, b = 60.68:
E(B-V) = 0.025 (Schlegel, Finkbeiner, & Davis 1998, ApJ 500, 525),
- R_V = 3.1
3) The GRB afterglow:
- Considering published GCN R-band data, analyzed according to
Beuermann et al. (1999, A&A 352, L26), we find:
alpha_1 = 0.85 +/- 0.04
alpha_2 = 1.55 +/- 0.02
t_break = 0.42 +/- 0.03 days,
after ignoring the several re-brightenings during the last days
- colors (best fit):
B-V = 0.39 mag
V-R = 0.34 mag
R-I = 0.47 mag
- we have taken into account the latest re-brightening episode and assumed that
a) alpha_2 remains constant and b) the color of the afterglow does not change
Output cocktail:
----------------
- Fig. 1: the light curve
- Fig. 2: the expected color evolution
We note that differences in the reported value for alpha_2 (cf. Li
et al. 2003, GCN 2078) can be explained by slightly different
selection criteria for the data chosen to perform the numerical fit.
http://www.tls-tautenburg.de/research/klose/grb.html
Warning:
--------
These results are based on a simple toy model. They provide only a
hint about what the strength of the SN signal could be since most
SN bumps found so far had a brightness of only 30-80% of SN 1998bw.