Central engines and radiation mechanisms of gamma …veresp.web.elte.hu/stuff/Veres_HSV16.pdfCentral...
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Central engines and radiation mechanismsof gamma-ray bursts
Peter Veres
CSPAR, University of Alabama in Huntsville
collaborators: Rob Preece, Adam Goldstein, Valerie Connaughton, Peter Meszaros,Alessandra Corsi, Bin-Bin Zhang, J. Michael Burgess and Eric Burns
8th Huntsville gamma-ray burst symposiumOctober 26, 2016
Peter Veres (UAH) Central engines and emission mechanism HSV 10/26/16 1 / 19
Gamma-ray Bursts - Overview
• Random directions on the sky(∼ few per week)
• Short/long divide in duration
• Broad non-thermal spectrumemerging complex picture
• Afterglow visible for ∼ week(s)
• Prompt: keV to . MeV,AG: radio to .TeV
• Deduce: compact object,Γ > 100, θjet ≈few ◦,Eiso = 1051 − 1055 erg
128-channel CSPEC or TTE data, are more reliable for suchweak events.
5. DISCUSSION
Figure 4 shows the sky distribution of GBM-triggered GRBsin Galactic coordinates. Crosses indicate long GRBs(T90>2 s) and asterisks indicate short GRBs. Both the longand short GRB locations do not show any obvious anisotropy,which is consistent with an isotropic distribution of GRBarrival directions. Also shown are the locations of GRBs thattriggered Swift-BAT in coincidence with GBM. Many of theseSwift coincident GRBs also have redshifts estimated bydetecting the optical afterglows with ground-based telescopes.
The histograms of the logarithms of GBM-triggered GRBdurations (T50 and T90) are shown in Figure 5. Using the
conventional division between the short and long GRB classes(T90�2 s and T90>2 s, respectively), we find that during thefirst 6 years there were 229 short GRBs and 1175 long GRBs.The short and long GRBs, as defined by their T90 in50–300 keV, may belong to two different classes (Kouveliotouet al. 1993). However, from the T90 distribution shown inFigure 5, the distinction seems to be less than obvious. Thereare also several claims in the literature concerning the existenceof three types of GRBs based on multiple GRB parameters likeduration, fluence, spectrum, spectral lag, peak-count rate, etc.,from the BATSE sample (Mukherjee et al. 1998; Horváthet al. 2006), Swift sample (Veres et al. 2010), and RHESSIsample (Ripa et al. 2012). The three groups are the familiarshort-hard GRBs, long-soft GRBs, and soft-intermediateduration GRBs bridging the other two groups. Hence, wedecided to independently assess the number of groups in the
Table 8GRB Fluence and Peak Flux (50–300 keV)
Trigger Fluence PF64 PF256 PF1024ID (erg cm−2) (ph cm−2 s−1) (ph cm−2 s−1) (ph cm−2 s−1)
bn080714086 3.54E-07±1.73E-08 1.52±0.74 0.91±0.36 0.43±0.18bn080714425 9.79E-07±1.36E-08 1.03±0.45 0.71±0.19 0.46±0.08bn080714745 3.26E-06±6.03E-08 4.41±1.66 3.27±0.71 2.82±0.36bn080715950 2.54E-06±3.52E-08 10.70±0.95 6.61±0.45 3.83±0.22bn080717543 2.37E-06±4.51E-08 2.14±1.03 1.30±0.47 1.05±0.23bn080719529 3.88E-07±1.47E-08 0.59±0.18 0.32±0.08 0.23±0.04bn080720316 3.88E-07±1.47E-08 0.59±0.18 0.32±0.08 0.23±0.04bn080723557 3.92E-05±1.15E-07 21.19±1.79 19.81±1.09 15.14±0.48bn080723913 7.45E-08±5.19E-09 2.62±0.66 2.14±0.32 0.69±0.13bn080723985 1.57E-05±1.07E-07 5.92±1.23 5.17±0.54 4.85±0.28
(This table is available in its entirety in machine-readable form.)
Figure 4. Sky distribution of GBM-triggered GRBs in celestial coordinates. Crosses indicate long GRBs (T90>2 s) and asterisks indicate short GRBs. Also shownare the GBM GRBs simultaneously detected by Swift (red squares).
12
The Astrophysical Journal Supplement Series, 223:28 (18pp), 2016 April Bhat et al.
3rd GBM GRB catalog Bhat+16
Peter Veres (UAH) Central engines and emission mechanism HSV 10/26/16 2 / 19
Gamma-ray Bursts - Overview
• Random directions on the sky(∼ few per week)
• Short/long divide in duration
• Broad non-thermal spectrumemerging complex picture
• Afterglow visible for ∼ week(s)
• Prompt: keV to . MeV,AG: radio to .TeV
• Deduce: compact object,Γ > 100, θjet ≈few ◦,Eiso = 1051 − 1055 erg 3rd GBM GRB catalog Bhat+16
Peter Veres (UAH) Central engines and emission mechanism HSV 10/26/16 2 / 19
Gamma-ray Bursts - Overview
• Random directions on the sky(∼ few per week)
• Short/long divide in duration
• Broad non-thermal spectrumemerging complex picture
• Afterglow visible for ∼ week(s)
• Prompt: keV to . MeV,AG: radio to .TeV
• Deduce: compact object,Γ > 100, θjet ≈few ◦,Eiso = 1051 − 1055 erg
100 101 102 103 104 105 106
E [keV]ν
Fν [
arb
itra
ry u
nit
s]
Comptonized
Band
Power law
Blackbody
Peter Veres (UAH) Central engines and emission mechanism HSV 10/26/16 2 / 19
Gamma-ray Bursts - Overview
• Random directions on the sky(∼ few per week)
• Short/long divide in duration
• Broad non-thermal spectrumemerging complex picture
• Afterglow visible for ∼ week(s)
• Prompt: keV to . MeV,AG: radio to .TeV
• Deduce: compact object,Γ > 100, θjet ≈few ◦,Eiso = 1051 − 1055 erg
10−3 10−2 10−1 100 101 102 103
Time from GBM trigger (d)
10−8
10−7
10−6
10−5
10−4
10−3
10−2
10−1
100
Flux
(Jy)
LAT 2−100 GeV (x1000)
LAT 0.1−2 GeV (x1000)
BAT 15−50 keV
XRT 0.2−10 keV
UVOT 180nm
P60/T100/GROND 0.6µm
UKIRT/GROND 2µmCARMA/PdBI 90 GHz
RTT/VLA 30 GHz (x10)
VLA 5.5 GHz (x100)
E1 E2 E3 E4 E5 E6 E7 E8 E9 E10 E11
Perley+14
Peter Veres (UAH) Central engines and emission mechanism HSV 10/26/16 2 / 19
Gamma-ray Bursts - Overview
• Random directions on the sky(∼ few per week)
• Short/long divide in duration
• Broad non-thermal spectrumemerging complex picture
• Afterglow visible for ∼ week(s)
• Prompt: keV to . MeV,AG: radio to .TeV
• Deduce: compact object,Γ > 100, θjet ≈few ◦,Eiso = 1051 − 1055 erg
credit: NASA/Swift/deWilde
Peter Veres (UAH) Central engines and emission mechanism HSV 10/26/16 2 / 19
Outline
• Central engine [Black hole and/or neutron star]
• Emission mechanism [thermal, synchrotron, Compton]
• Case studies [GRB 130427A, GW 150914-GBM]
• Jet composition [baryonic, magnetic]
Peter Veres (UAH) Central engines and emission mechanism HSV 10/26/16 3 / 19
Outline
• Central engine [Black hole and/or neutron star]
• Emission mechanism [thermal, synchrotron, Compton]
• Case studies [GRB 130427A, GW 150914-GBM]
• Jet composition [baryonic, magnetic]
Peter Veres (UAH) Central engines and emission mechanism HSV 10/26/16 3 / 19
Outline
• Central engine [Black hole and/or neutron star]
• Emission mechanism [thermal, synchrotron, Compton]
• Case studies [GRB 130427A, GW 150914-GBM]
• Jet composition [baryonic, magnetic]
Peter Veres (UAH) Central engines and emission mechanism HSV 10/26/16 3 / 19
Central engine sources
Black Hole
Neutron Star
BH-NS merger
Single
Binary
accreting BH
NS-NS merger (magnetar)
BH-BH merger?
Magnetar
Single
BinaryNeutron Star
• (Indirect) evidence:• Long GRB progenitor: collapsar• Short GRB progenitor: compact binary
• Invisible central engine: black hole + disc or magnetar
• (?) direct observations near → GW [see also talk by Bing Zhang]
Peter Veres (UAH) Central engines and emission mechanism HSV 10/26/16 4 / 19
Central engines: Black hole + accretion disk
• Hyper-accreting BH• Neutrino annihilation:νν → e± powers jet along rotaxis. E budget: disk material. 1054 erg
• Blandford Znajek: E budget:BH rotation ∼ 1054 erg
credit: Bartos+13
Peter Veres (UAH) Central engines and emission mechanism HSV 10/26/16 5 / 19
Magnetars
• Rapidly rotating (P∼ 1 ms) NS(near breakup speed)
• Highly magnetized (B∼1015 G)- to transfer NS energy to jet
• Observational signature: X-rayplateau + break / extendedemission
• Possible issue: Emax = Erot =2×1052R2
6P−2ms
M1.4M�
erg . EGRB
(talk by Fruchter) credit: Bartos+13
Peter Veres (UAH) Central engines and emission mechanism HSV 10/26/16 6 / 19
Binary Black hole mergers - unlikely progenitors
• For EM: mass stripped form NS to form acc. disk to tap BH energy→ need at least a NS component.
• Difficult to keep disk around BH binary for long time
• Considered after GW 150914-GBM
• Loeb15: Star /w massive He core forms 2 BHs
• Woosley16: need binary/ EM delayproblematic
• Perna+16: dead disk around one BH,re-energized by merger
• Zhang16: norm. charge: ∼ 10−5, links to FRB
• Lyutikov16: unreasonable magn. fieldrequired.
• ... and many more: Li+16, Yamazaki+16,Janiuk+16, Murase+16, Kimura+16,Veres+16
Shock-heateddisk,MRIactiveandactivelyaccretingontoBHS
Durationofaccretion(GRB)
Deaddisk
Tidallyheatedouterrim,MRIactive
BlackHoles
Catastrophic,fulldisk-heating
Steady-stateouterrimheating
Perna+16
• Are BBH mergers (short)GRB sources? → need more observations
Peter Veres (UAH) Central engines and emission mechanism HSV 10/26/16 7 / 19
Scenarii for GRB prompt emission
• Photospheric models (dissipative/non-dissipative)• Blackbody / shocks + synchrotron / geometry / τ � 1 dissipation
• Internal shocks• Shocks + Synchrotron / Self-Compton / magnetic fields
• External shock (?)• Synchrotron / Self-Compton
Peter Veres (UAH) Central engines and emission mechanism HSV 10/26/16 8 / 19
Scenarii for GRB prompt emission
• Photospheric models (dissipative/non-dissipative)• Blackbody / shocks + synchrotron / geometry / τ � 1 dissipation
• Internal shocks• Shocks + Synchrotron / Self-Compton / magnetic fields
• External shock (?)• Synchrotron / Self-Compton
Peter Veres (UAH) Central engines and emission mechanism HSV 10/26/16 8 / 19
Scenarii for GRB prompt emission
• Photospheric models (dissipative/non-dissipative)• Blackbody / shocks + synchrotron / geometry / τ � 1 dissipation
• Internal shocks• Shocks + Synchrotron / Self-Compton / magnetic fields
• External shock (?)• Synchrotron / Self-Compton
Peter Veres (UAH) Central engines and emission mechanism HSV 10/26/16 8 / 19
GRB dynamics and prompt emission models
Energy (Γ0 = E/Mc2 � 1) released in a volume ∼ R30 .
→ Jet expands/accelerates→ Reaches Γ ∼ Γ0
→ Dissipates (kinetic/magnetic) energy→ Decelerates
Γ(R) =
R/R0 if R < Rsat
Γ0 if Rsat < R < Rdec
(R/Rdec)−3/2 if Rdec < R.
• Photospheric models→ Dissipative photosphere (. 1010 cm)→ Non-dissipative photosphere (∼ 1010 cm)
• Internal shocks (∼ 1014 cm)
• External shocks (∼ 1016 cm)
107 108 109 1010 1011 1012 1013 1014 1015 1016 1017 1018
Radius approx. [cm]
101
102
Γ (
R)
Γ(R)∝R
Γ(R)∝R 0
∼Rphot
∼RIS
∼RES
Γ(R)∝R−3/2
Peter Veres (UAH) Central engines and emission mechanism HSV 10/26/16 9 / 19
Prompt emission models - Internal shocks
• Unsteady outflow → Γ & 100 shocks (τ � 1)→ accelerated particles,magnetic field, synchrotron
• Explains variability, broad nonthermal spectrum→ easy to calculate analytically
• Radiation from RIS ≈ tvarcΓ20 ≈ 3× 1014tvar,0Γ2
0,2 cm
• But: low efficiency, spectral index, dim photosphere → problems
• Zhang+11: ICMART: 2 step: highly magnetized ∼ RIS coll., thenmagnetic reconn. at . RES
Peter Veres (UAH) Central engines and emission mechanism HSV 10/26/16 10 / 19
Prompt emission models - Internal shocks
• Unsteady outflow → Γ & 100 shocks (τ � 1)→ accelerated particles,magnetic field, synchrotron
• Explains variability, broad nonthermal spectrum→ easy to calculate analytically
• Radiation from RIS ≈ tvarcΓ20 ≈ 3× 1014tvar,0Γ2
0,2 cm• But: low efficiency, spectral index, dim photosphere → problems• Zhang+11: ICMART: 2 step: highly magnetized ∼ RIS coll., then
magnetic reconn. at . RES
Credit: Bing Zhang
Peter Veres (UAH) Central engines and emission mechanism HSV 10/26/16 10 / 19
Prompt emission - photospheric models
• Energy released at the photosphere: τ = 1 ⇒Rphot = 6× 1012L52Γ−3
0,2 cm
• Non dissipative: geometry, Γ profile, fuzzy→ broadened Planck
• Fan+12: explains correlations
• Zhang+13: GRB 110721A: line of deathEp . 3.92kBT0 ≈ 4.7L
1/452 R
−1/20,7 MeV
• Rees+05: Dissipation below the photosphere (τ � 1)
• High efficiency, explains high Epeak & distr.
• Giannios08: magnetic dissipation• Beloborodov10, Vurm+11: n-p collisional
heating (+magnetic)• Meszaros+11: shocks @photosphere
• Jet simulations (Lazzati16) include more refined physicse-γ decoupling [see poster by Parsotan].
• Most likely model, but potentially violates emissionradius constraints Rdissip. > 1015−16 cm.
10-4 10-3 10-2 10-1 100 101 102 103100
101
102
103
104
10-6 10-5 10-4 10-3 10-2 10-1 100 101 102 103 104100
101
102
103
104
Black circles: Lv et al. 2012 sampleRed triangels: GRB 090902B
(a)
(b)
Black circles: Zhang et al. 2012 sampleRed triangles: GRB 090902B
L/1052 (erg/s)
E p (keV
)
50 51 52 53 54 550
1
2
3
4
5z=3.512
Log
Ep (1
+z) /
keV
Log Liso (erg s-1)
z=0.382
Peter Veres (UAH) Central engines and emission mechanism HSV 10/26/16 11 / 19
Prompt emission - photospheric models
• Energy released at the photosphere: τ = 1 ⇒Rphot = 6× 1012L52Γ−3
0,2 cm
• Non dissipative: geometry, Γ profile, fuzzy→ broadened Planck
• Fan+12: explains correlations
• Zhang+13: GRB 110721A: line of deathEp . 3.92kBT0 ≈ 4.7L
1/452 R
−1/20,7 MeV
• Rees+05: Dissipation below the photosphere (τ � 1)
• High efficiency, explains high Epeak & distr.
• Giannios08: magnetic dissipation• Beloborodov10, Vurm+11: n-p collisional
heating (+magnetic)• Meszaros+11: shocks @photosphere
• Jet simulations (Lazzati16) include more refined physicse-γ decoupling [see poster by Parsotan].
• Most likely model, but potentially violates emissionradius constraints Rdissip. > 1015−16 cm.
10-2 100 102 104 E [MeV]
1048
1049
1050
1051
E
L E
[
erg
s-1
]
εB=0
10−3
0.01
0.1
0.5
2
α=−1.2
Vurm+11
0
2×1052
4×1052
6×1052
8×1052
L iso
(erg
/s)
MCRaT light curveL13 approximation (/10)MCRaT peak energy
0
20
40
60
80
100
120
140
160
180
Peak
Frequency
(ke
V)
0 10 20 30 40 50Time since jet launch (s)
0.5
1.0
1.5
2.0
α
β
α 6
4
2
β
Lazzati+16
Peter Veres (UAH) Central engines and emission mechanism HSV 10/26/16 11 / 19
Prompt emission models - External shocks?
• Jet plows into ISM, decelerates, shocksform, B field enchanced, synchrotron
• Radiation fromRdec ≈ 6× 1016 E
1/353 n
−1/30 Γ
−2/30,2.5 cm
• Peak energy
Ep ∼ 800 ε2e,−1n
1/20 ε
1/2B,−1Γ4
0,2.5keV
• Invoked for afterglow
• Strong variability (tv ∼ 10−2 s) inprompt is difficult to explain
• May be relevant in unique cases(see talk by Yu)
Peter Veres (UAH) Central engines and emission mechanism HSV 10/26/16 12 / 19
Prompt emission models - External shocks?
• Jet plows into ISM, decelerates, shocksform, B field enchanced, synchrotron
• Radiation fromRdec ≈ 6× 1016 E
1/353 n
−1/30 Γ
−2/30,2.5 cm
• Peak energy
Ep ∼ 800 ε2e,−1n
1/20 ε
1/2B,−1Γ4
0,2.5keV
• Invoked for afterglow
• Strong variability (tv ∼ 10−2 s) inprompt is difficult to explain
• May be relevant in unique cases(see talk by Yu)
101
Time [s]
102
103
Ep
[keV
]
Burgess+15
Peter Veres (UAH) Central engines and emission mechanism HSV 10/26/16 12 / 19
Case study 1 - GRB 130427A
• Preece+14: first pulse -synchrotron lab
• Ep ∝ t−1 curvature: OK, L ∝ E 1.5p not OK
• L ∝ E 1.5p expanding shell synch.: OK, ⇒
Ep ∝ t−4 not OK→ no single model can explain these relations
• Kouveliotou+13: synchrotron/ no SSC, butE synch.max violated
Ackermann+14: no SSCAliu+14: VHE upper limitsLiu+13, Fraija+16: FS/RS + SSCVurm+14: pairs: synch. + external Comptonde Pasquale+16: long term obs.
Peter Veres (UAH) Central engines and emission mechanism HSV 10/26/16 13 / 19
Case study 1 - GRB 130427A
• Preece+14: first pulse -synchrotron lab
• Ep ∝ t−1 curvature: OK, L ∝ E 1.5p not OK
• L ∝ E 1.5p expanding shell synch.: OK, ⇒
Ep ∝ t−4 not OK→ no single model can explain these relations
• Kouveliotou+13: synchrotron/ no SSC, butE synch.max violated
Ackermann+14: no SSCAliu+14: VHE upper limitsLiu+13, Fraija+16: FS/RS + SSCVurm+14: pairs: synch. + external Comptonde Pasquale+16: long term obs.
Peter Veres (UAH) Central engines and emission mechanism HSV 10/26/16 13 / 19
Case study 2. - GW 150914-GBM
Assume: GW 150914 and GW 150914-GBM are related.A binary black hole merger produced a GRB.Ask: What can we learn about GRB prompt emission models? Veres+16
• M1=36 M�, M2=29 M�, MBH=62 M�
• a ≈ 0.67, z ≈ 0.09
• Gravitational radius:RG = GMBH/c
2 = 9.2× 106 cm
• Innermost stable radius → GRB launchingradius: R0 ≈ 3.5RG = 3.2× 107 cm.
• Best explanation: untriggered, short GRB [seetalk by Goldstein]
• Best fit spectrum: power law
• T ≈ 1 s, ∆Tγ−GW ≈ 0.4 s
Peter Veres (UAH) Central engines and emission mechanism HSV 10/26/16 14 / 19
GW 150914-GBM - Spectrum
• Fluence 2.4× 107 erg/cm−2 (40precentile of short GBM GRBs)
• Weak signal: only 2 spectralparameters can be constrained
• Spectrum: power law→ needs a cutoff (3 param.)
• Fix 1 out of 3 parameters
• MC sim. spectral parametersconsistent with data
• Conclusion: Epeak & 1 MeV(∼ 95%)
2 1 0 1αComp
10-7
10-6
Fluence
(1
0-1
00
0 k
eV
) [e
rg c
m−
2]
Epeak=1 MeV (fixed)
102 103 104 105
Epeak [keV]
αComp=-0.42 (fixed)
Peter Veres (UAH) Central engines and emission mechanism HSV 10/26/16 15 / 19
GW 150914-GBM - Spectrum
• Fluence 2.4× 107 erg/cm−2 (40precentile of short GBM GRBs)
• Weak signal: only 2 spectralparameters can be constrained
• Spectrum: power law→ needs a cutoff (3 param.)
• Fix 1 out of 3 parameters
• MC sim. spectral parametersconsistent with data
• Conclusion: Epeak & 1 MeV(∼ 95%)
2 1 0 1αComp
10-7
10-6
Fluence
(1
0-1
00
0 k
eV
) [e
rg c
m−
2]
Epeak=1 MeV (fixed)
102 103 104 105
Epeak [keV]
αComp=-0.42 (fixed)
Peter Veres (UAH) Central engines and emission mechanism HSV 10/26/16 15 / 19
GW 150914-GBM - testing prompt emission models
• Non-dissipative photosphere:
EPHpk . 3.92× kT0 ≈ 0.6
(L
Lobs
)1/4 (R0R∗
)−1/2MeV ∼not OK
• Diss. phot. Epk . 10 MeV (for Lobs) OK
• Int. sh.: E ISpk . 0.1
(L
Lobs
)1/6 (∆R0
)−5/6dt
1/6−3 ε
1/2B ε
4/3e MeV. ∼not OK
• External shocks:Synchrotron emission, atRdec assuming εB ,εe(=0.5) get:n ∼ 10−3 cm−3 andΓ ∼ 2000
102 103 104
Γ
10-6
10-5
10-4
10-3
10-2
10-1
100
n [
cm−
3]
B= 0.1 G
B= 1.0 G
B= 10.0 GB=100.0 G
B=1000.0 G
R=1.0e+17 cm
R=1.0e+16 cm
R=1.0e+15 cm
tdec =
0.01 s
tdec =
1.00 st
dec =0.40 s
tdec =
0.10 s
Fν, p= 124 µJy
Fν, p= 242 µJyFν, p= 171 µJy
Ep =
1.0 MeV
Ep =
3.0 MeV
Peter Veres (UAH) Central engines and emission mechanism HSV 10/26/16 16 / 19
Jet composition - What carries the energy?
• Multiple methods for hints on jetscomponents
• Bromberg+14: T90 plateau → jetbreakout timescale ∼ 10s → baryondom.
• Zhang+10: BB non-detection in GRB080916C → σ & 20 [see also talk byRyde]
• Veres+14: modified initial acceleration:Γ ∝ Rµ, µ = 1/3-magnetic →µ = 1-baryonic jets
Peter Veres (UAH) Central engines and emission mechanism HSV 10/26/16 17 / 19
Jet composition - What carries the energy?
• Multiple methods for hints on jetscomponents
• Bromberg+14: T90 plateau → jetbreakout timescale ∼ 10s → baryondom.
• Zhang+10: BB non-detection in GRB080916C → σ & 20 [see also talk byRyde]
• Veres+14: modified initial acceleration:Γ ∝ Rµ, µ = 1/3-magnetic →µ = 1-baryonic jets
10−2
10−1
100
101
102
103
10−3
10−2
10−1
100
101
102
T90
dN
/dT
90
BATSE
Swi ft/3
Fermi/50
Peter Veres (UAH) Central engines and emission mechanism HSV 10/26/16 17 / 19
Jet composition - What carries the energy?
• Multiple methods for hints on jetscomponents
• Bromberg+14: T90 plateau → jetbreakout timescale ∼ 10s → baryondom.
• Zhang+10: BB non-detection in GRB080916C → σ & 20 [see also talk byRyde]
• Veres+14: modified initial acceleration:Γ ∝ Rµ, µ = 1/3-magnetic →µ = 1-baryonic jets
100 101 102 103 104 105 106 107
101
102
103
104
η = 200 T=1 keV σ= 15
η = 470 T=10 keV σ= 20
Tmax=50 keV; σ= 20
E [keV]
ν F ν
[keV
/cm
2 /s]
abcde
Peter Veres (UAH) Central engines and emission mechanism HSV 10/26/16 17 / 19
Jet composition - What carries the energy?
• Multiple methods for hints on jetscomponents
• Bromberg+14: T90 plateau → jetbreakout timescale ∼ 10s → baryondom.
• Zhang+10: BB non-detection in GRB080916C → σ & 20 [see also talk byRyde]
• Veres+14: modified initial acceleration:Γ ∝ Rµ, µ = 1/3-magnetic →µ = 1-baryonic jets
107 108 109 1010 1011 1012 1013 1014 1015 1016 1017 1018
Radius approx. [cm]
101
102
Γ (
R)
Γ(R)∝R
Γ(R)∝R 0
∼Rphot
∼RIS
∼RES
Γ(R)∝R−3/2
Drenkhahn+02,Meszaros+11,Bosnjak+12, McKinney+12,
Gao+15
Peter Veres (UAH) Central engines and emission mechanism HSV 10/26/16 17 / 19
Jet composition - What carries the energy?
• Multiple methods for hints on jetscomponents
• Bromberg+14: T90 plateau → jetbreakout timescale ∼ 10s → baryondom.
• Zhang+10: BB non-detection in GRB080916C → σ & 20 [see also talk byRyde]
• Veres+14: modified initial acceleration:Γ ∝ Rµ, µ = 1/3-magnetic →µ = 1-baryonic jets
107 108 109 1010 1011 1012 1013 1014 1015 1016 1017 1018
Radius approx. [cm]
101
102
Γ (
R)
Γ(R)∝R 1/3
Γ(R)∝R
Γ(R)∝R 0
∼Rphot
∼RIS
∼RES
Γ(R)∝R−3/2
Drenkhahn+02,Meszaros+11,Bosnjak+12, McKinney+12,
Gao+15
Peter Veres (UAH) Central engines and emission mechanism HSV 10/26/16 17 / 19
Jet composition from Epeak-T correlation
Observations:
• Ep ∝
L3µ−14µ+2 Γ
− 3µ−14µ+2
0 R
−5µ4µ+2
0 accel.
L−1/2 Γ30 coast
• T ∝
L14µ−5
12(2µ+1) Γ
2−2µ6µ+3
0 R− 10µ−1
6(2µ+1)0 accel.
L−5/12 Γ8/30 R
1/60 coast
• Ep ∝{
T6(3µ−1)(14µ−5) accel.
T 1.2 coast
Peter Veres (UAH) Central engines and emission mechanism HSV 10/26/16 18 / 19
Jet composition from Epeak-T correlation
Observations:
100 101 102 103
kT [keV]
100
101
102
103
104
Epeak
[keV
]
GRB 090719A
α=2.33±0.27µ=0.39±.01
100 101 102 103
kT [keV]
101
102
103
104
Epeak
[keV
]
GRB 130427A
α=1.02±0.05baryonic jet
• Ep ∝
L3µ−14µ+2 Γ
− 3µ−14µ+2
0 R
−5µ4µ+2
0 accel.
L−1/2 Γ30 coast
• T ∝
L14µ−5
12(2µ+1) Γ
2−2µ6µ+3
0 R− 10µ−1
6(2µ+1)0 accel.
L−5/12 Γ8/30 R
1/60 coast
• Ep ∝{
T6(3µ−1)(14µ−5) accel.
T 1.2 coast
Peter Veres (UAH) Central engines and emission mechanism HSV 10/26/16 18 / 19
Jet composition from Epeak-T correlation
Observations:
100 101 102 103
kT [keV]
100
101
102
103
104
Epeak
[keV
]
GRB 090719A
α=2.33±0.27µ=0.39±.01
100 101 102 103
kT [keV]
101
102
103
104
Epeak
[keV
]
GRB 130427A
α=1.02±0.05baryonic jet
Theory:
• Ep ∝
L3µ−14µ+2 Γ
− 3µ−14µ+2
0 R
−5µ4µ+2
0 accel.
L−1/2 Γ30 coast
• T ∝
L14µ−5
12(2µ+1) Γ
2−2µ6µ+3
0 R− 10µ−1
6(2µ+1)0 accel.
L−5/12 Γ8/30 R
1/60 coast
• Ep ∝{
T6(3µ−1)(14µ−5) accel.
T 1.2 coast
Peter Veres (UAH) Central engines and emission mechanism HSV 10/26/16 18 / 19
Jet composition from Epeak-T correlation
Observations:
100 101 102 103
kT [keV]
100
101
102
103
104
Epeak
[keV
]
GRB 090719A
α=2.33±0.27µ=0.39±.01
100 101 102 103
kT [keV]
101
102
103
104
Epeak
[keV
]
GRB 130427A
α=1.02±0.05baryonic jet
Theory:
• Ep ∝
L3µ−14µ+2 Γ
− 3µ−14µ+2
0 R
−5µ4µ+2
0 accel.
L−1/2 Γ30 coast
• T ∝
L14µ−5
12(2µ+1) Γ
2−2µ6µ+3
0 R− 10µ−1
6(2µ+1)0 accel.
L−5/12 Γ8/30 R
1/60 coast
• Ep ∝{
T6(3µ−1)(14µ−5) accel.
T 1.2 coast
Peter Veres (UAH) Central engines and emission mechanism HSV 10/26/16 18 / 19
Jet composition from Epeak-T correlation
Observations:
100 101 102 103
kT [keV]
100
101
102
103
104
Epeak
[keV
]
GRB 090719A
α=2.33±0.27µ=0.39±.01
100 101 102 103
kT [keV]
101
102
103
104
Epeak
[keV
]
GRB 130427A
α=1.02±0.05baryonic jet
Theory:
• Ep ∝
L3µ−14µ+2 Γ
− 3µ−14µ+2
0 R
−5µ4µ+2
0 accel.
L−1/2 Γ30 coast
• T ∝
L14µ−5
12(2µ+1) Γ
2−2µ6µ+3
0 R− 10µ−1
6(2µ+1)0 accel.
L−5/12 Γ8/30 R
1/60 coast
• Ep ∝{
T6(3µ−1)(14µ−5) accel.
T 1.2 coast
Peter Veres (UAH) Central engines and emission mechanism HSV 10/26/16 18 / 19
Jet composition from Epeak-T correlation
Observations:
100 101 102 103
kT [keV]
100
101
102
103
104
Epeak
[keV
]
GRB 090719A
α=2.33±0.27µ=0.39±.01
100 101 102 103
kT [keV]
101
102
103
104
Epeak
[keV
]
GRB 130427A
α=1.02±0.05baryonic jet
Theory:
• Ep ∝
L3µ−14µ+2 Γ
− 3µ−14µ+2
0 R
−5µ4µ+2
0 accel.
L−1/2 Γ30 coast
• T ∝
L14µ−5
12(2µ+1) Γ
2−2µ6µ+3
0 R− 10µ−1
6(2µ+1)0 accel.
L−5/12 Γ8/30 R
1/60 coast
• Ep ∝{
T6(3µ−1)(14µ−5) accel.
T 1.2 coast
GRB Name α (Ep ∝ Tα) Jet Type µ081224A 1.01± 0.14 baryonic −090719A 2.33± 0.27 magnetic 0.39±0.01100707A 1.77± 0.07 magnetic 0.42±0.01110721A 1.24± 0.11 baryonic −110920A 1.97± 0.11 magnetic 0.4±0.01130427A 1.02± 0.05 baryonic −
Veres+13, Burgess+14Peter Veres (UAH) Central engines and emission mechanism HSV 10/26/16 18 / 19