tev 06 1 high energy emissions from gamma-ray bursts (grbs) soeb razzaque penn state university
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TeV 06TeV 06 11
High Energy Emissions High Energy Emissions from Gamma-ray Bursts from Gamma-ray Bursts
(GRBs)(GRBs)
Soeb RazzaqueSoeb Razzaque
Penn State UniversityPenn State University
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TeV 06 2
Gamma Ray BurstGamma Ray BurstMost violent explosion in the Universe!
• Non-thermal -ray spectrum
• Total energy output in -rays ~1049-1051 erg
• Rate ~1000/year
• Isotropic distribution
• Peak photon energy ~0.1-1 MeV
Bright flash of -rays outshining
the entire universe for
secondsCredit: Tyce DeYoung
• Extra-galactic (redshift~1-2)
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TeV 06 3
Bi-modal distribution of burst duration Different origins
Highly variable -ray emission(down to milliseconds) Compact source
Long bursts
Short bursts
Time (s)
GRB Prompt EmissionGRB Prompt Emission
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TeV 06 4
GRB AfterglowGRB AfterglowLate time (hours-days) emission of X-ray, UV, optical light
Feb 28Feb 28 GRB 970228 GRB 970228 Mar2Mar2
• Identify host galaxy redshift
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TeV 06 5
• Isotropic-equivalent total energy outflow
• Initial fireball radius
Relativistic jetted outflow
erg/s 10-10 5250oL
cm 10-10 76oR
MeV 101oT
1
• Initial temperature
Accretion disk
Core collapse
Binary mergers
X
OUV
ISM
Afterglow
GRB
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TeV 06 6
Gamma-ray SpectrumGamma-ray Spectrum
pe
e
dNE
dE
• Origin: Internal shocks
e-synchrotron radiation (low energy) Inverse Compton scattering (high energy)
• Time-averaged spectrum fitted by broken power-laws (Band fit)
Non-thermal
• Theoretical model:
e - shock acceleration
Break energy
~0.1-1 MeV
=2 for strong shock
2,1
keEE
bE ,
E
E
E
dEdN /
Observation:
Synch/IC spectrum( 2) / 2
,;ppk
dNE E E
dE
• Fast cooling:
shock accelerated e - population lose energy completely (e to ) within dynamic time
~0.1 model parameter
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TeV 06 7
Afterglow SpectrumAfterglow Spectrum
Sari, Piran & Narayan ’98
Break frequency decreases in time at rate depending on constant (ISM) or wind (density r -2 ) ambient medium
Reverse | Forward shocks
Ambientmedium
e -synchrotron cooling time longer than dynamic time
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TeV 06 8
TeV TeV -ray Detection Status-ray Detection Status► Milagrito: GRB 970417aMilagrito: GRB 970417a
Tentative 3Tentative 3 detection detection Unknown redshift (less than Unknown redshift (less than
100 Mpc?)100 Mpc?) Atkins et al. ‘00Atkins et al. ‘00
► Tibet Array:Tibet Array: 50-60 GRB stacked in time 50-60 GRB stacked in time
coincidence with MeVcoincidence with MeV 66 significance significance Amenomori et al. ‘96Amenomori et al. ‘96
► GRAND: GRB 971110GRAND: GRB 971110 Reported significance 2.7Reported significance 2.7 Poirier et al. ’03Poirier et al. ’03
► MAGIC: GRB050713aMAGIC: GRB050713a Flux upper limitsFlux upper limits Albert et al. ‘06Albert et al. ‘06
MilagroMilagro
Tibet ArrayTibet Array
GRAND ArrayGRAND Array
MAGICMAGIC
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TeV 06 9
GeV GeV -ray Detection-ray Detection
t<14 s
t <47 s
t < 80 s
t < 113 s
t < 211 s
Gonzalez et al. ‘03
• Handful of GRB detection at ~GeV by EGRET• Hard spectra and delayed emission• More energy in HE component?• Need more data!
GRB 941017GRB 970217
Futuredetect
or
Hurley et al. ‘94
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TeV 06 10
High Energy High Energy -rays from -rays from GRBsGRBs
► Electromagnetic process: Inverse Compton (IC)Electromagnetic process: Inverse Compton (IC) Maximum electron energy ~100 TeVMaximum electron energy ~100 TeV Maximum Maximum -ray energy ~TeV-ray energy ~TeV Inefficient in the Klein-Nishina limitInefficient in the Klein-Nishina limit
► Hadronic Process: Photomeson Hadronic Process: Photomeson 00 decay decay Maximum proton energy ~10Maximum proton energy ~102020 eV eV Maximum Maximum -ray energy ~EeV-ray energy ~EeV In general inefficient: opacity~1 (long) <1 (short)In general inefficient: opacity~1 (long) <1 (short)
► Single or multi (internal-external shocks) zone(s) Single or multi (internal-external shocks) zone(s) emission?emission?
► High energy High energy -rays may attenuate at the source-rays may attenuate at the source► -rays with energy >100 GeV are attenuated in -rays with energy >100 GeV are attenuated in
background radiation fields (IR/CMB)background radiation fields (IR/CMB)
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TeV 06 11
Which Model?Which Model?
p-sync
IC
e-sync
tdec ~2
Zhang & Meszaros ’01Granot & Guetta ‘03
Boettcher & Dermer ‘98
Internal shock MeV -raysExternal shock high energy Insignificant proton contribution
One zone model for MeV and HE Time delay by slower p cascadeand secondary radiation
Early Afterglow: >100 MeV
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TeV 06 12
-ray Opacity of the Universe-ray Opacity of the Universe
Coppi & Aharonian ‘97
e
Baring ‘99
>100 GeV -rays from GRBs suffer attenuation in IR & CMB background
High energy -ray attenuation from GRBs may probe astrophysical model(s)
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TeV 06 13
HE Photon Opacity in GRBsHE Photon Opacity in GRBs n rsh
E,ssa,thE,pk,th
Optical depth
Internal shock radius
Razzaque, Meszaros & Zhang ‘04
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TeV 06 14
GRB Prompt and Delayed GRB Prompt and Delayed SpectraSpectra
52,
,
,
10 erg/s
2.5
1
800
1 s
1 MeV
10 keV
iso
pk
ssa
L
z
t
E
E
; GRB bkg bkg HEe e e Re-processed high energy -ray
10-17 G10-20 G
IG B-field
Razzaque, Meszaros & Zhang ‘04
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TeV 06 15
Diffuse <TeV Diffuse <TeV -rays from GRBs-rays from GRBs
-3 -1GRB 0.44 Gpc yr
GRB316; 1 s; 20 st t
Casanova, Dingus & Zhang ‘06
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TeV 06 16
>TeV >TeV -ray from UHE Cosmic-ray-ray from UHE Cosmic-ray
>1 TeV -ray fluence1051 erg GRB energy at 100 Mpc
Shock-acceleration in GRB ≥1020 eV cosmic-rays
0CR bkg
TeV
/ /
; synchrotron
p pe p n
e e
Cascades on IR/CMB background radiation
Delayed emission ~day
Waxman & Coppi ’96Dermer ’02Armengaud, Sigl & Miniati ‘06
Patchy IGM (80% voids w. B10-15 G, 20% w. B~10-11 G) TeV Fluence ~2% of energy in GZK protons
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TeV 06 17
pn
fpfn ,,
e
1rel
np
Inelastic p-n scattering
n-p decouples
GRB Fireball EvolutionGRB Fireball Evolution
0
e
e
e
e
pn
Derishev, Kocharovsky & Kocharovsky ‘99
, , ~ 300n f p f
coasting fireball
Initial fireball
Coulomb Compton
nuclear
e
p
n
~ 1
pn
Initial fireball
e
p
n
e
p
n
Baryon loading
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TeV 06 18
n-pn-p Decoupling in Short GRB Decoupling in Short GRB' '/o n pn n
Razzaque & Meszaros ‘06
50
60
10 erg/s
10 cm
kinL
R
n-p DecouplingRadius Rnp~RTh
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TeV 06 19
• Only photons produced at photosphere may escape un-attenuated
n-pn-p Decoupling Gamma-rays Decoupling Gamma-rays
• 0 decay photon energy
Probability 0
'Th Th( ) / 0.4np npP R R R
0
0
6 -2 -12 2,
,
ˆ2 10 cm s
4 L p f p
P LN
D m c
• Flux from an SGRB at z=0.1
• GLAST : Too small effective area
• MILAGRO25
eff cm 105A
Energy below threshold?
'cm ,
10 GeV70 MeV~
60 GeVp fE
(LGRB)
(SGRB)
Bahcall & Meszaros ‘00
Razzaque & Meszaros ‘06
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TeV 06 20
Short GRB Model Flux Short GRB Model Flux PredictionsPredictions
GRBGRB DistanceDistance
(z)(z)L_isoL_iso
(erg/s)(erg/s)DurationDuration
(s)(s)EE(GeV)(GeV)
FluxFlux
(/cm(/cm22/s)/s)
040924040924
050509b050509b
051103051103
051221051221
0.8590.859
0.2250.225
0.001(?)0.001(?)
0.5470.547
1.48E521.48E52
8.6E488.6E48
2.6E472.6E47
1.7E511.7E51
0.60.6
0.1280.128
0.170.17
1.41.4
2222
5959
3636
2222
9.7E-69.7E-6
2.3E-72.3E-7
8.6E-48.6E-4
2.3E-62.3E-6
' '10 ; =316 ; / 10kin iso o n pL L n n
Data credits: Pablo Saz Parkinson
Model parameters
• These are still below detection• Need bigger detectors with lower threshold
Predictions
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TeV 06 21
GeV Gamma-rays from Short GeV Gamma-rays from Short GRBGRB
2,2 ( / ms)i p fR c t
' '/o n pn n
0 b e
e
2, ,c e p fE m c
, ,2.82 ( / )b o o p fE T R R
Razzaque & Meszaros ‘06
IC scattering
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TeV 06 22
Late X-ray Flares in GRBLate X-ray Flares in GRBVarious models:
• Refreshed shocks • IC from reverse shock• External density bumps• Multiple component jet• Late central engine activity
Main constraints: sharp rise and decline
GeV-TeV rays:
IC scattering of x-ray photons by external forward shocked electron
Burrows et al. ’05, Zhang et al. ‘05
X-ray flare
Underlying afterglowlight curve t -0.8
GRB
Wang, Li & Meszaros ‘06
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TeV 06 23
HE HE from Old GRB Remnants from Old GRB Remnants
HESS J1301-631 Age: 1.5×104 yr ; Distance: 12 kpc
≤10’ 10’≤≤25’ 25’≤≤1o
Atoyan, Buckley & Krawczynski ‘06
0 decaymodel
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TeV 06 24
HE HE from Old GRB Remnants from Old GRB Remnants
Ioka, Kobayashi & Meszaros ‘04
GRB jet: p +n neutron decay: n e -
e - CMB e - HE TeV W49B
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TeV 06 25
ConclusionConclusion► GRBs are the brightest MeV GRBs are the brightest MeV -ray transient sources -ray transient sources
in the universein the universe► GeV and TeV (tentative) GeV and TeV (tentative) -rays have been observed -rays have been observed
from a few burstsfrom a few bursts► Both Both LeptonicLeptonic and and HadronicHadronic models may account for models may account for
GeV data GeV data Need more data! Need more data! ► Short GRBs may produce ~100 GeV Short GRBs may produce ~100 GeV -rays-rays
Less luminous than long GRBs but much nearerLess luminous than long GRBs but much nearer Less attenuation in background radiationLess attenuation in background radiation
► TeV detection in current detectors requires luminous TeV detection in current detectors requires luminous and nearby GRBsand nearby GRBs
► Need more GeV-TeV data Need more GeV-TeV data need bigger detector! need bigger detector!