High energy High energy emission in emission in Gamma Ray Gamma Ray
BurstsBurstsGabriele GhiselliniGabriele Ghisellini
INAF – Osservatorio Astronomico di INAF – Osservatorio Astronomico di BreraBrera
“Pillars” of knowledge
Criterion:Criterion: the most important and not controversial facts constructing the basics of our understanding
1st Pillar: GRBs are cosmological(therefore large energetics, but how large? Depends on collimation…). Thanks to BeppoSAX and its team, led by Luigi Piro, and to Paczynski)
Cost
a+
20
07
Metz
eger+
20
07970508; z=0.835970508; z=0.835
970228970228
Attention: not bolometric for Swift
2nd Pillar: GRBs have large (From GeV; msec variability; radio scintillation; theory)
Frail+ 1997: ~4 two weeks after
970508970508
Abdo+ 2009; Ghirlanda+ 2010; GG+2010; Ackermann+ 2010: >1000
090510090510
3rd Pillar: Prompt+Afterglow(but X-rays may be late prompt). Energy is NOT released ENTIRELY during the prompt.
Pir
o
Pir
o
astr
o-p
h/0
00
14
36
astr
o-p
h/0
00
14
36
SAX X-ray SAX X-ray afterglow afterglow light curvelight curve
PrompPromptt
Willin
gale
et
al.
W
illin
gale
et
al.
2007
2007
Before Swift After Swift
4th Pillar: Long & ShortBut there are exceptions + extended emission
SHORT LONG
Short – HardShort – Hard Long - SoftLong - Soft
5th Pillar: Same t of spikes during the prompt
Spikes have Spikes have same same durationduration
A process A process that repeats that repeats itselfitself
6th Pillar: Supernova connection i.e. progenitors. But there are exceptions. Evidence can be gathered only from nearby, under-luminous GRBs.
No SN060614
Della Valle+ 2006
Woosley Bloom 2006
Campana+ 2006
060218
7th Pillar: Phenomenology of the prompt & “afterglow” Diversity, but some common behavior exists. 2 examples:
Eiso erg
Ep
eak
k
eV
1000
100
10
Short
Short
Long
??
steep
steep
flat
flares
Log time
Log X
-ray fl
ux
The total energy of the prompt correlates with peak of the spectrum
The early X-ray afterglow is “typical”
Ideas (and enigmas)
Central EngineCentral EngineBlack hole or magnetar, or more exotic? (quark star?)
GRBs from quark stars: one-way membrane for baryons, only e+-, photons, B-fields escape… Paczynski & Haensel 2005 MNRAS 362, L4
Magnetars:Giant flares to explain SGRBs + some short (but numbers are not ok)
During the magnetar phase: flat X-ray plateaux
Magnetar BH transition (re-edition of SupraNova).
Magnetic or matter dominated?
~100
Internal pressure: Random bulk randomDisorder order disorder“Heavy FB” optical flash
Blandford: bulk randomorder disorderLight “FB” no opt. flash, no inertia, very
large
Dissipation at large R. Variability through mini-jets or small scale instabilities? (Lyutikov)
R~109
cm
=?
Annihilation
In any case:~Everybody:At the start: B0~1015 G for BZConversion of Poynting to kineticCyclo >mec2
Smaller scattering cross section
Different E different B0?Is the funnel useful to collimate? No, it is a myth, short can do without, as well as blazars
R~106
cm
=?
L ~ B02R0
2c/8~ 1051B15
2R62
erg/s
Efficiency is small.
Big prompt/afterglow ratioEven bigger if X-rays are late prompt. GeV relax, but not enough.
Internal shocks: collisions within the flow. Dissipate RELATIVE kinetic energy
5%5%
22//11
Lazzati+ 1999
Willingale+ 2007
Log E
aft
erg
low
Log Eprompt
EEaft aft ~ E~ Epromptprompt/10/10
Efficiency is small.
Big prompt/afterglow ratioEven bigger if X-rays are late prompt. GeV relax, but not enough.
Internal shocks: collisions within the flow. Dissipate RELATIVE kinetic energy
Deep impacts? Lazzati+ 2009
What makes the light we see?
For the prompt: we don’t know. we don’t know. Must be efficient: short cooling time. If synchro, or IC: F(E) = k E-1/2. SSC even steeper: kE-3/4
Kaneko+ Kaneko+ 20062006
Nava PhD thesis Nava PhD thesis 20092009
Lin
e o
f d
eath
Lin
e o
f d
eath
fo
r c
oolin
g e
-fo
r c
oolin
g e
-
Lin
e o
f d
eath
Lin
e o
f d
eath
fo
r n
on
coolin
g
for
non
coolin
g
e-
e-
“Afterglows”: X-rays and the optical have often different behaviors.
opticaloptical
X-ray
TTAAIs this “real” afte
rglow? i.e. e
xternal
Is this “real” afte
rglow? i.e. e
xternal
shock?
shock?
2 components? Late prompt+forward shock light curves resemble t-5/3, like rate of fallback material
~5/3~5/3
latelate promptprompt
LogLog
Log
Log
FF
GBMGBM
EEpeakpeak
Spectral-energy Spectral-energy correlationscorrelations
Amati, Ghirlanda, Firmani, Yonetoku…Under attack from the start (selection effects). Fiery replies.
Ghirlanda 2009
Ep-Eiso0.5
97 GRBs
““Amati”
Amati”
Amati, Ghirlanda, Firmani, Yonetoku…Under attack from the start (selection effects). Fiery replies.
Ghirlanda 2009
Ep-Eiso0.5
97 GRBs
““Amati”
Amati”
Amati, Ghirlanda, Firmani, Yonetoku…Under attack from the start (selection effects). Fiery replies.
Ghirlanda 2009
Ep-Eγ1.03
Ep-Eiso0.5
97 GRBs
29 GRBs
““Amati”
Amati”
““Ghi
rland
a
Ghi
rland
a
””
Yet we see the “Epeak-L” correlation in single GRBs
Luminosity [erg/s]Luminosity [erg/s]
EEp
eak
peak [keV
][k
eV
]R
ate
Rate
Gh
irla
nd
a+
20
09
EEpeak peak =k L=k L1/21/2
FERMI-FERMI-GBMGBM
This is not d
ue to selecti
on
This is not d
ue to selecti
on
effects.!!
effects.!!
High energy
Hurley et al. 1994
EGRET: 100 MeV-10 GeV
18 GeV
GG
+ 2
010
GG
+ 2
010
Fermi: 100 MeV - 100 GeV
short
LogLog
Log
Log
FF
GBMGBM
LAT
vs vs
vs vs
LogLog
Log
Log
FF
GBMGBM LAT
tt--10/710/7 Spectrum and Spectrum and decay: afterglow decay: afterglow = forward shock = forward shock in the circum-in the circum-burst mediumburst medium
The 4 brightest LAT GRBsThe 4 brightest LAT GRBs
This is This is puzzlingpuzzling
Adiabatic fireballs:Adiabatic fireballs:
LLbolombolom = a t = a t-1-1
Radiative fireballs:Radiative fireballs:
LLbolombolom = b t = b t-10/7-10/7
tt--10/710/7
Rad
iative!
Rad
iative!
The 4 brightest LAT GRBsThe 4 brightest LAT GRBs
tt--10/710/7
Rad
iative?
Rad
iative?
The 4 brightest LAT GRBsThe 4 brightest LAT GRBs
e
e
e+
e-
e
e+
e-
e
p
Time TimeTime Time
GRB 090510GRB 090510
ShortShort Very hardVery hard z=0.903z=0.903 Detected by the LAT up to 31 GeV!!Detected by the LAT up to 31 GeV!! Well defined timingWell defined timing Delay: ~GeV arrive after ~MeV Delay: ~GeV arrive after ~MeV
(fraction of seconds)(fraction of seconds) Quantum Gravity? Violation of Lorentz Quantum Gravity? Violation of Lorentz
invariance?invariance?
Fermi-L
AT
Fermi-L
AT
0.6s0.5
s
Time since trigger (precursor)Time since trigger (precursor)
precursorprecursor 8-260 keV8-260 keV
0.26-5 0.26-5 MeVMeV
LAT all LAT all
>>100 MeV100 MeV
>>1 GeV1 GeV31 31 GeVGeV
Ab
do e
t al 2009
Ab
do e
t al 2009
Delay between GBM and Delay between GBM and LATLATDue to Lorentz Due to Lorentz invariance violation?invariance violation?
Different Different componentcomponent
30 GeV0.1 GeV
1
2
3
3
4
AveragAveragee
Time Time resolveresolvedd
0.5-1s0.5-1s
F
(F(
) ) [e
rg/c
m[e
rg/c
m22/s
]
/s]
Energy [keV]Energy [keV]
Ab
do e
t al 2009
Ab
do e
t al 2009
If LAT and GBM radiation are If LAT and GBM radiation are cospatial: cospatial: >1000 to avoid photon->1000 to avoid photon-photon absorption photon absorption If If >1000: deceleration of the fireball >1000: deceleration of the fireball occurs early occurs early early afterglow! early afterglow!
If If >1000: large electron energies >1000: large electron energies synchrotron afterglow!synchrotron afterglow!
Ghirlanda+ Ghirlanda+ 20102010
tt22 tt-1.5-1.5
Fermi-
Fermi-
LATLAT
0.1-1 GeV0.1-1 GeV
>1 GeV>1 GeV
T-T* [s]T-T* [s]
Gh
irla
nd
a+
2010
Gh
irla
nd
a+
2010
T-T* [s]T-T* [s]
Gh
irla
nd
a+
2010
Gh
irla
nd
a+
2010~MeV and ~GeV emission are NOT ~MeV and ~GeV emission are NOT
cospatial. cospatial. But the ~GeV emission is…But the ~GeV emission is… No measurable delay in arrival time of No measurable delay in arrival time of high energy photons: thigh energy photons: tdelaydelay<0.2 s <0.2 s
Strong limit to quantum gravity Strong limit to quantum gravity
MMQGQG > 4.7 M > 4.7 MPlanckPlanck
ConclusionsConclusions
““Paradigm”: internal+external Paradigm”: internal+external shocks, synchrotron for both: shocks, synchrotron for both: it it does not workdoes not work
Fermi/LAT detection Fermi/LAT detection large large Early high energy (and powerful) Early high energy (and powerful) afterglowafterglow
Decay suggests Decay suggests radiativeradiative afterglowsafterglows
GRB 090510:GRB 090510: Violation of the Violation of the Lorentz invariance?Lorentz invariance? No (not yet) No (not yet)
4th Pillar: Long & Short (8)Similar spectra, especially for the first second of long
Fluence Fluence Peak FluxPeak Flux
Nava+
N
ava+
201
0201
0
Amati corr.
Ghirlanda et al. 2009
Yonetoku corr. EnergeticEnergeticss
LuminositieLuminositiess
LONG GRBsLONG GRBs
A2:Short vs Long: A2:Short vs Long: < < Energetics ; Energetics ; == Luminosities Luminosities
Ghirlanda et al. 2009
FERMI GRBs & TIME INTEGRATED correlations
For the prompt: we don’t know. Must be efficient: short cooling time. If synchro, or IC F(E) = k E-1/2. SSC even steeper: kE-3/4
1057 photons: large entropy (# of photons per particle), >1
For the afterglow: when it is forward shock it is synchrotron, but when it is late prompt… we don’t know.
Isotropic or collimated?Attention: not bolometric for Swift
Isotropic or collimated?
Strongest argument: Ghirlanda relation
<100
Nava+ 2006; Ghirlanda+ Nava+ 2006; Ghirlanda+ 22000077
“Am
at
i”
“Ghir
landa” 1- cos 1- cos jetjet
For long GRBs: Wolf-Rayet? Isolated or binary? (to give angular momentum). What triggers the SN, if a BH forms? The jet? In all SN Ic?
For short: merging NS-NS?
Isotropic or collimated?
But this? No jet breaks
<100
EEp
eak
peak(1
+z
(1+
z))
Gh
irla
nd
a,
Gh
isellin
i &
Lazz
ati
G
hir
lan
da,
Gh
isellin
i &
Lazz
ati
2004
2004
rr
EEp
eak
peak(1
+z
(1+
z))
Peak energy vs. True energyPeak energy vs. True energy
EE peak
peak
E E
true
true
0.70.7
HomogeneouHomogeneouss densitydensity
Nava e
t al.
2006
Nava e
t al.
2006
Wind-like Wind-like densitydensity
Nava e
t al.
2006
Nava e
t al.
2006
““Lor
entz
Lore
ntz
iinn
vvaa
rrii
aann
tt””
NN~
cons
t~10
~co
nst~
105757
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