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
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)
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
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
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
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
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
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
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
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)
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
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)
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
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
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
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
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
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
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
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
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
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
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
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
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!
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