大野 雅功(広島大学)
On behalf of the Fermi
LAT/GBM collaboration	

– Highest gamma-ray fluence (>10-3 erg cm-2)– Highest observed gamma-ray energy (95 GeV)
– Longest lived gamma-ray emission (19 hours)– Within the closest 5% of GRBs (z = 0.34)
30-50keV	
50-300keV	
300-5MeV	LAT > 10 MeV	
6 hours LAT all-sky map	2013.09.04

高エネルギーガンマ線で見る極限宇宙@宇宙線研究所	

LAT>100MeV	2• Introduction –GRBs and high energy gamma-rays• GRB observations by Fermi- Fermi Gamma-ray Space Telescope- onboard trigger and autonomous repoint observation- Fermi GRB detection statistics• Fermi recent results- temporally extended emission- delayed onset of high energy emission- bulk Lorentz factor of GRB jet- Limit on EBL model & Lorentz invariance violation (LIV)• Prospect for CTA• Summary	2013.09.04

高エネルギーガンマ線で見る極限宇宙@宇宙線研究所	

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J. T. Bonnel (NASA)	

2013.09.04

E2NE erg/cm2/s	 Photon/s/cm2/MeV	

Intense hard X-ray to gamma-ray emission discovered at the 60’s
• Event rate : 1-2 per day• Wide diversity in light curve (0.1-1000s duration)• Cosmological distance (z~0.1-9)
Briggs et al. 1999	
• Bimodal duration distribution(short/long GRB)
• Non-thermal spectrum

0.01

0.1

高エネルギーガンマ線で見る極限宇宙@宇宙線研究所	

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MeV	
100	4

•

After the spiky prompt emission, there is long-lived (~day)afterglow from radio to X-rays
Late phase afterglow shows smooth light curve
Swift/BAT (gamma)
Swift/XRT (X-ray)
Swift/UVOT, GROND, ROTSE(optical/UV)	

Flux density (mJy)	

•~1day	10
2013.09.04

102

103
104105Time since burst (s)	106	高エネルギーガンマ線で見る極限宇宙@宇宙線研究所	

5•Prompt emission	afterglow	

Still many unknown, unclear…
emission mechanism of gamma-ray, jet formation, .. Etc
key observation: high-energy gamma-ray emission	

Piran 2003	

2013.09.04

高エネルギーガンマ線で見る極限宇宙@宇宙線研究所	

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GRB940217(Hurley et al. 94)
GeV photons
up to 90min after the trigger	

GRB941017(Gonzaletz et al. 03)
Temporary distinct
HE spectral component	

-18 to 14 sec

14 to 47 sec

47 to 80 sec

80-113 sec

113-211 sec
2013.09.04

EGRET detected > 100 MeV photons
from a few GRBs
Different behavior from <100 MeV photons	Long-lived emissionExtra spectral component
 constrain on emission mechanism
Highest energy photon
 bulk Lorentz factor of jetCosmology, fundamental physics
Extra galactic background light
Lorentz invariance violation
Need large FoV, high sensitivity	

高エネルギーガンマ線で見る極限宇宙@宇宙線研究所	

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Silicon-Strip detectors- Identification &direction
measurement of γ-rays
CsI calolimetor- Energy measurement
ACD (plastic scintillators)- background rejection-Efficient observing mode
-Wide FoV
-Low deadtime-Large effective area
-Good angular resolution-Energy coverage	
2013.09.04

高エネルギーガンマ線で見る極限宇宙@宇宙線研究所	

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GBM/NaI: 8 keV – 1 MeV	

GBM/BGO: 200 keV – 40 MeV	•> 7 decades of energy range•Large FoV(GBM:~4π,LAT: ~65deg(90deg for LLE))• > 10 times sensitivity of EGRETLAT LLE: 10 MeV – 100 MeV(preliminary)	
LAT Transient: > 100 MeV	LAT(>100MeV) preliminary	2013.09.04

高エネルギーガンマ線で見る極限宇宙@宇宙線研究所	

9 GBM/LAT on-board processing (10—15 s):
GCN alert within 10—15 s from the trigger time through TDRSS (alert, location).
Now 2 s~ 150s windows are also used for on-board search
We have only one trigger for GRB 090510

 LAT ground processing (a few hours after data downlink)
Final location, spectrum (1st circular).
Final location, high-energy flux and spectrum, afterglow search results (2nd circular).
Data downlink may take > a half of day once ARR is triggered2013.09.04

高エネルギーガンマ線で見る極限宇宙@宇宙線研究所	

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GBM FSW triggers Autonomous Repoint Request (ARR)
S/C slew to the GBM position up to 2.5 hours subject to earth-limb constraint	
ARR for GRB 090926A	

ARR triggered for almost a half of LAT events  helpful for extended emission search	
2013.09.04

高エネルギーガンマ線で見る極限宇宙@宇宙線研究所	

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11 month Fermi LAT count map	GBM 2-year catalog
LAT 3-year catalog

Fermi LAT GRB catalog(in prep.)	
Up to GRB110731	

GBM LGRB: green circles
GBM SGRB: orange squares
LAT detections (35): blue squares

PRELIMINARY•The GBM detects ~250 GRBs / year, ~half in the LAT FoV•The LAT detected 62 GRBs up to 2013/09–~Half with more accurate follow-up localisations by Swift and ground-based observatories(GROND, Gemini-S, Gemini-N, VLT)
–13 redshift measurements, from z=0.34 (GRB 130427A) to z=4.35 (GRB 080916C)
2013.09.04

高エネルギーガンマ線で見る極限宇宙@宇宙線研究所	

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1. Temporally extended high energy emission-- emission mechanism GRB (mainly in afterglow phase)
2. Delayed onset of high energy photons-- onset time of afterglow ?
-- prompt emission origin? leptonic/hadronic ?
3. Extra component in the prompt emission spectrum-- Band model crisis
4. Highest energy photon-- constraint on bulk Lorentz factor, EBL, and LIV-- new high energy photons from new analysis method
2013.09.04

高エネルギーガンマ線で見る極限宇宙@宇宙線研究所	

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LAT (>100 MeV) emission lasts systematically longer than GBM emission	
4000

500

2000

GRB090926181
NaI (20 keV -- 250 keV)

10000
246812000

BGO (200 keV -- 5 MeV)

2500

10000

2000

8000

1500

6000

1000

4000

50

200

40102468

RATE [Hz]Counts/Bin

400

Energy [MeV]LATLLE > 10 MeV

100T90 (100 MeV-10 GeV) [s]RATE [Hz]

20000
4000
2000

Counts/Bin

103090926A
080916C

102090510

100LAT

110-1

3101020090902B

30000

6000

3000

RATE [Hz]

6000

1000

8000

Counts/Bin

GRB090926	

GRB090926181
NaI (8 keV -- 20 keV)RATE [Hz]Counts/Bin

1500

2040
Time since T06080100x=y1

10102

T90 (50 keV-300 keV) [s]Fermi LAT 1st GRB catalog(Fermi LAT Collab. 2013 in press arXiv1303.2908)	
2013.09.04

高エネルギーガンマ線で見る極限宇宙@宇宙線研究所	

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Luminosity of extended emission
Smoothly decreases with temporal
Index of about 1

Detection of break from 3 events(090510, 090902B, 090926)
Transition from prompt-dominate
Phase (?)	090510090902B
090926A	

Fermi LAT 1st GRB catalog(Fermi LAT Collab. 2013 in press arXiv1303.2908)	
2013.09.04

高エネルギーガンマ線で見る極限宇宙@宇宙線研究所	

15GRB 080916C photon index	

GRB 080916C flux curve	
10-1_= 1.78 ± 0.33-2-1_1= 1.19 ± 0.13

10-1.5-310Photon Index

Flux [ph cm-2 s-1]

_2= 1.76 ± 0.29

10-4-510-2-2.5-3-3.5-610-4

10-7
10-2

10-1

1102

10Time-Trigger [s]31010-2

10-1

110102

310Time-Trigger [s]Stable spectrum of extended emission with photon index of around -2.0	
Fermi LAT 1st GRB catalog(Fermi LAT Collab. 2013 in press arXiv1303.2908)	
2013.09.04

高エネルギーガンマ線で見る極限宇宙@宇宙線研究所	

16LAT(>100MeV) emission is systematically “delayed” from GBM emission	
GRB090926A	

1000
500

GRB090926181
NaI (20 keV -- 250 keV)

>10s delay 	

20000
4000
10000
246812000

BGO (200 keV -- 5 MeV)

2500

10000

2000

8000

1500

6000

1000

4000

50

200

104

RATE [Hz]Counts/Bin

400

Energy [MeV]LATLLE > 10 MeV

100

T05 (100 MeV-10 GeV) [s]

30000

6000

3000

102

2000

2000

Counts/Bin

4000

RATE [Hz]Counts/Bin

8000

6000

RATE [Hz]GRB090926181
NaI (8 keV -- 20 keV)RATE [Hz]Counts/Bin

1500

10090902B090926A080916C

1090510

10-1024680LAT

x=y310024681021002040
Time since T06080

100

T05 (50 keV-300 keV) [s]Fermi LAT 1st GRB catalog(Fermi LAT Collab. 2013 in press arXiv1303.2908)	
2013.09.04

高エネルギーガンマ線で見る極限宇宙@宇宙線研究所	

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Extra power-law (or cut-off)component is required significantly High fluence	
for 6 LAT events with high S/N
GRB090926A (Ackermann et al. 2011)	

Normal fluence/on-axis angle	

Fermi LAT 1st GRB catalog(Fermi LAT Collab.fluence	
2013 in press arXiv1303.2908)	
2013.09.04

高エネルギーガンマ線で見る極限宇宙@宇宙線研究所	

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Simple Band model does notHigh fluence	
represent spectral features forhigh S/N LAT event
Band model crisis. Further spectral
modeling are investigating
GRB090926A (Ackermann et al. 2011)	

Normal fluence/
on-axis angle	

Fermi LAT 1st GRB catalog(Fermi LAT Collab.fluence	
2013 in press arXiv1303.2908)	
2013.09.04

高エネルギーガンマ線で見る極限宇宙@宇宙線研究所	

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2013.09.04

高エネルギーガンマ線で見る極限宇宙@宇宙線研究所	

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090902B

102Rest Frame Photon Energy (GeV)

080916C
090926A

090510

Possible correlation between
Eiso and highest photon energy

090323

Short GRB is outlier ?
Need more sample !	

110731A
090328

10

Several-tens-of-GeV photons
In GRB frame

100414A

091003

1

Fermi LAT 1st GRB catalog(Fermi LAT Collab. 2013 in press arXiv1303.2908)	
10-1

1Eiso,GBM (1 keV-10 GeV) [102013.09.04

1054erg]

Highest photon energy is usefulfor-Limit on bulk Lorentz factor-Constraint on synchrotron model-EBL model-Lorentz invariance violation (LIV)

高エネルギーガンマ線で見る極限宇宙@宇宙線研究所	

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Due to large luminosity and small emitting region, optical depth for theγ-γ -> e+e- pair production is too large to observe the non-thermal
emission from GRB  compactness problem.
Relativistic motion (Γ>>1) could avoid this compactness problem 	Γmin can be derived using observed
highest energy photon 	2013.09.04

Gehrels et al. arXiv1301.0841	

高エネルギーガンマ線で見る極限宇宙@宇宙線研究所	

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•

•

In the context of the early afterglow model, the delayed LAT
onset is due to the transition between the coasting fireball andthe self similar phase (Blandford & McKee 1976, Rees &Meszaros 1994)
Peak-flux time of the LAT is of the order of the fireballdeceleration time	

Similar result toγ-γ opacity limit	

2013.09.04

高エネルギーガンマ線で見る極限宇宙@宇宙線研究所	

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From the detection of high-energy photons:-- maximum photon energy that an electron can produce bysynchrotron taking into account the acceleration/cooling time-- computing maximum energy of an electron (to complete atleast 1 Lamor radius)  constraint on maximum photon
energy by synchrotron (Kumar et al. 2012, Sari & Nakar 2012)

E syn,max ~ 29.5(1+ z) −1 (Γ/1000)GeVRest frame	
102€
Observed	Energy [GeV]•2013.09.04

10

110-1

110102

103

104

ArrivalTime [s]高エネルギーガンマ線で見る極限宇宙@宇宙線研究所	

24•

Pass-8 : new revision of event-level analysis data by Fermicollaboration• Improvement event reconstruction at each stage-- TKR: (before) pattern recognition seeded by CAL(Pass8) New pattern recognition decoupled from CAL-- CAL: (before) All crystals hits grouped together(Pass8) introduce new clustering algorithm to reduce missreconstruction due to background ghost event-- ACD: (before) use absolute distance between ACD and TKR(Pass8) propagate covariance matrix and measure distance• Will be published by Fermi team
• Test analysis to show improvement the data analysis	
Atwood et al. 2013 ApJ, 774, 76	2013.09.04

高エネルギーガンマ線で見る極限宇宙@宇宙線研究所	

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•Example for CAL new reconstruction	Previous event reconstruction	

Pass8 reconstruction	

TKR	

CAL	
We will loss such miss-reconstructedevent	

2013.09.04

高エネルギーガンマ線で見る極限宇宙@宇宙線研究所	

26•Find 4 new photons which were miss-reconstructed inprevious event class• 27.4 GeV photon from GRB 080916C at T0+40.5s (z=4.35),
147 GeV in GRB frame !
• If synchrotron origin, Γ>5000 is required (unrealistic?)• More useful to constrain EBL model
27.4 GeV photon(147 GeV in GRB frame)
From GRB 080916C	

The most constraining gamma-ray
So far from GRBs
(similar constrain from AGN)	

2013.09.04

高エネルギーガンマ線で見る極限宇宙@宇宙線研究所	

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•Some quantum gravity models allow violation of Lorentz
invariance : (vph)≠c•

A high-energy photon Eh would arrive after (or possibly beforein some models) a low-energy photon El emitted together	

PulsarGRB(Kaaret 99)(Ellis 06)
15161015 1.8x10 0.9x10 1016

AGN(Biller 98)

GRBAGN(Boggs 04) (Albert 08)

4x1016 10171.8x10170.2x1018

GRB080916C Planck mass
1018

1.5x1018

min MQG(GeV/c2)
10191.2x1019

High-z, large ΔE (not so high E for EBL) is preferable  GRB is a good target !	
2013.09.04

高エネルギーガンマ線で見る極限宇宙@宇宙線研究所	

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•
•
•
•

Estimate lower limit of MQG,1 for various
Δt, ΔE
Highest energy photon from GRB 090510
is 31 GeV at 0.83 s after trigger
Most conservative case: 31 GeV photon
starts from any <1MeV emission
Δt < 859 ms, MQG,1/Mplank > 1.19

• This new limit MQG,1/Mplank > several
is much stronger than the previous result
 Greatly constrain the QG model (n=1)(Abdo et al. 2010)2013.09.04

高エネルギーガンマ線で見る極限宇宙@宇宙線研究所	

29• Delayed-onset and temporally extended high energy emission- common in LAT observed GRBs
- several models to explain such temporal feature (leptonic/hadronic/early afterglow)• Extra spectral component- extra spectral component in prompt emission phase can beseen for LAT GRBs with good S/N (so far, 6 GRBs)- GRB090926A and GRB100728A shows high-E spectral cut-off- need further spectral model• Observation of highest energy photon- minimum bulk Lorentz factor of jet could be Γ~1000- maximum energy for synchrotron- Fermi LAT new event reconstruction algorithm found new highenergy photons (147 GeV in GRB frame)- Useful for EBL and LIV constraint
2013.09.04

高エネルギーガンマ線で見る極限宇宙@宇宙線研究所	

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– Highest gamma-ray fluence (>10-3 erg cm-2)– Highest observed gamma-ray energy (95 GeV)
– Longest lived gamma-ray emission (19 hours)– Within the closest 5% of GRBs (z = 0.34)
30-50keV	
50-300keV	
300-5MeV	LAT > 10 MeV	
6 hours LAT all-sky map	LAT>100MeV	

GRB 130427A challenges the model that
Temporally extended emission is nonthermal
Synchrotron emission	2013.09.04

高エネルギーガンマ線で見る極限宇宙@宇宙線研究所	

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Fermi LAT collab. Science submitted	

2013.09.04

高エネルギーガンマ線で見る極限宇宙@宇宙線研究所	

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Fermi LAT collab. Science submitted	

2013.09.04

高エネルギーガンマ線で見る極限宇宙@宇宙線研究所	

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Fermi LAT collab. Science submitted	

Assume fast acceleration on a timescale shorter than Lamor timescale	

95 GeV, and 32 GeV photons cannot originate from leptonic standard synchrotronradiation.	
2013.09.04

高エネルギーガンマ線で見る極限宇宙@宇宙線研究所	

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Mostly taken from Inoue et al. 2013 paper (arXiv 1301.3014)	

•Origin of delayed, temporally extended emission- Time variability of high energy photon is an important key- A number of GeV photon is still poor for Fermi-LAT- CTA light curve with good statistics can be compared toprompt gamma-ray light curve• Constraint on EBL- high energy photon (>100GeV) could come >100s after trigger- EBL cut-off can be observed by CTA• Constraint on LIV- to improve on LIV constraint for GRB 090510, need < 30sobservation for 1 TeV photon- wide-field mode would be useful (? Event rate: 2-3 GRB/year)- other statistical approach, use X-ray flare in afterglow.. 	
2013.09.04

高エネルギーガンマ線で見る極限宇宙@宇宙線研究所	

35• Fermi satellite is now observing GRBs normally• Delayed-onset and temporally extended high energy emission- common in LAT observed GRBs, but origin is still discussing• Extra spectral component- can be seen from some of high S/N events, need furtherspectral model• Observation of highest energy photon- highest energy photon from GRBs is very useful for various
GRB science (i.e., constrain on bulk Lorentz factor,synchrotron model, EBL, LIV.. etc)
• Monster GRB 130427A challenges synchrotron emission modelfor high energy emission• Need much more GeV photons for more study.  CTA !	

2013.09.04

高エネルギーガンマ線で見る極限宇宙@宇宙線研究所	

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