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GR
B "
afte
rglo
ws"
X-r
ay a
fter
glow
s w
ere
dis
cove
red
by
sate
llite
s
Th
e in
ten
sity
falls
like
t-(
~1)
for
seve
ral d
ays:
Op
tica
l af
terg
low
s w
ere
dis
cove
red
b
y te
lesc
opes
.
Th
e op
tica
l in
ten
sity
fal
ls li
ke t
-(
~1)
for
w
eeks
-as
lon
g as
it c
an b
e m
easu
red
:
A s
tran
ge"
bu
mp
"ap
pea
rs f
orso
me
GR
Bs
afte
r1-
2 d
ays.
Som
e h
ost
gala
xies
hav
e b
een
dis
cove
red
b
y th
e H
ub
ble
tel
esco
pe:
Tod
ay m
any
sate
llite
s an
d
tele
scop
es a
re
wor
kin
g to
geth
er, m
ore
or le
ss
auto
mat
ical
ly t
o tr
ace
gam
ma-
ray
bu
rsts
an
d t
hei
r af
terg
low
s an
d
hos
t ga
laxi
es
Tod
ay
man
y h
osts
h
ave
bee
n
fou
nd
Mos
t of
th
em s
eem
to
be
in a
n in
ten
se
per
iod
of
star
for
mat
ion
(b
lue
gala
xies
).
Such
reg
ion
s ar
e al
so k
now
n t
o h
ave
a lo
t of
st
ar d
eath
s (s
up
ern
ovae
).
Th
ese
GR
Bs
also
see
m t
o b
e in
th
e ou
ter
regi
ons
of t
hei
r ga
laxi
es.
GR
B r
edsh
ifts
(z v
alu
es)
are
seen
intw
o d
iffe
ren
t w
ays:
abso
rpti
onlin
es in
th
e G
RB
afte
rglo
w
emis
sion
lines
in t
he
ligh
t fr
om t
he
hos
t ga
laxy
Con
clu
sion
s fr
om r
edsh
ifts
(of
a fe
w d
ozen
GR
Bs)
Hig
hz-
valu
es (
typ
ical
ly 1
)=
> v
ery
larg
e d
ista
nce
s(t
ypic
ally
> 7
bill
ion
ligh
t-ye
ars)
Ver
yh
igh
en
ergy
ou
tflo
ws
~10
52to
1054
ergs
or
~10
53er
gs p
er s
ec(
100
gala
xies
wit
h 1
011st
ars
each
)if
the
rad
iati
on is
isot
rop
ic
Bea
min
gis
like
ly, b
ecau
se o
ther
wis
e th
e to
tal o
utf
low
wou
ld b
e "
imp
ossi
ble
" t
o ex
pla
in.
(Th
ere
are
also
det
ails
in t
he
afte
rglo
w
that
cou
ld c
ome
from
bea
min
g)
A b
eam
ing
wit
hin
, for
inst
ance
, on
ly 1
/10
0 of
th
e fu
ll so
lid a
ngl
e m
ean
s th
at t
he
tota
l en
ergi
es a
re "
only
" 1
050to
1052
ergs
.B
ut
then
th
ere
exis
t 10
0 ti
mes
as
man
y G
RB
s, o
f w
hic
h w
e se
e on
ly 1
%.
Wh
at a
re t
hey
?F
ast
tim
e d
evel
opm
ent
of a
GR
B =
>th
e ga
mm
as a
re c
reat
ed in
a s
mal
lvol
um
e.
Exa
mp
le: A
GR
B t
hat
last
s fo
r 10
sec
sm
ust
be
smal
ler
than
10
ligh
t-se
cs(e
arth
-to-
moo
n is
~1
ligh
t-se
c)
Som
ewh
at s
low
er d
evel
opm
ent
for
X r
ays
and
ligh
t =
> t
he
afte
rglo
w t
akes
pla
ce in
a
larg
er v
olu
me
A p
ossi
ble
sce
nar
io:
Exp
losi
on b
y/in
a v
ery
smal
l "en
gin
e"
=>
ou
tflo
w o
f ve
ry f
ast
char
ged
par
ticl
es
=>
gam
mas
fro
m c
ollis
ion
s in
som
e n
earb
y(s
urr
oun
din
g?)
den
se m
ediu
m (
gas?
)
=>
aft
ergl
ows
from
col
lisio
ns
late
r on
"P
roof
":
Th
e X
-ray
aft
ergl
ow lo
oks
like
syn
chro
tron
rad
iati
on (
Bre
mss
trah
lun
g)
Th
e b
eam
ing
can
com
e fr
om t
he
"en
gin
e" o
r fr
om a
n in
hom
ogen
eou
s su
rrou
nd
ing
med
ium
Th
e "
engi
ne"
??
Th
ere
are
two
typ
es o
f m
odel
s:
1. T
wo
colli
ding
obje
cts
2. O
ne
colla
psin
gob
ject
1. T
wo
colli
din
g ob
ject
s
Som
e fa
vou
rite
s:N
eutr
on s
tar
+ n
eutr
on s
tar
Bla
ck h
ole
+ b
lack
hol
eN
eutr
on s
tar
+ b
lack
hol
eQ
uar
k st
ar +
qu
ark
star
