The association of GRB 060218 with a supernova and the evolution of the shock wave.
Although the link between long gamma-ray bursts (GRBs) and supernovae has been established, hitherto there have been no observations of the beginning of a supernova explosion and its intimate link to a GRB. In particular, we do not know how the jet that defines a gamma-ray burst emerges from the star's surface, nor how a GRB progenitor explodes. Here we report observations of the relatively nearby GRB 060218 (ref. 5) and its connection to supernova SN 2006aj (ref. 6). In addition to the classical non-thermal emission, GRB 060218 shows a thermal component in its X-ray spectrum, which cools and shifts into the optical/ultraviolet band as time passes. We interpret these features as arising from the break-out of a shock wave driven by a mildly relativistic shell into the dense wind surrounding the progenitor. We have caught a supernova in the act of exploding, directly observing the shock break-out, which indicates that the GRB progenitor was a Wolf-Rayet star.
Campana
S
S
INAF-Osservatorio Astronomico di Brera, via E. Bianchi 46, I-23807 Merate, LC, Italy. sergio.campana@brera.inaf.it
Mangano
V
V
Blustin
A J
AJ
Brown
P
P
Burrows
D N
DN
Chincarini
G
G
Cummings
J R
JR
Cusumano
G
G
Della Valle
M
M
Malesani
D
D
Mészáros
P
P
Nousek
J A
JA
Page
M
M
Sakamoto
T
T
Waxman
E
E
Zhang
B
B
Dai
Z G
ZG
Gehrels
N
N
Immler
S
S
Marshall
F E
FE
Mason
K O
KO
Moretti
A
A
O'Brien
P T
PT
Osborne
J P
JP
Page
K L
KL
Romano
P
P
Roming
P W A
PW
Tagliaferri
G
G
Cominsky
L R
LR
Giommi
P
P
Godet
O
O
Kennea
J A
JA
Krimm
H
H
Angelini
L
L
Barthelmy
S D
SD
Boyd
P T
PT
Palmer
D M
DM
Wells
A A
AA
White
N E
NE