1. CALET と MAXI で観測されている突発天体
坂本 貴紀、川久保 雄太、 橋本 達也 (青学)、中平 聡志 (JAXA)、芹野 素子 (理研)

2. Contents CALET MAXI CALET-MAXI simultaneously observed GRBs
Overview of CALET
GRBs observed by CALET Gamma-ray Burst Monitor
MAXI
MAXI observation of GRBs
MAXI Unidentified Short Soft Transient (MUSST)
CALET-MAXI simultaneously observed GRBs
GRB A: Broad-band prompt emission observation
GRB A: Soft X-ray emission before the main episode
FRB : Re-visit Swift/BAT data (bonus)
11/30/16
High energy astro

3. Overview of CALET: CALorimetric Electron Telescope
11/30/16
High energy astro

4. CALET (CALorimetric Electron Telescope)
Observatory of high energy electrons and gamma-rays
Observation of high energy cosmic-rays
All sky gamma-ray survey (> 10 GeV)
High energy transients (GRBs, SGRs, …)
CGBM/HXM
CGBM/SGM
CAL
ASC
MAXI
Scientific instruments:
CALorimeter (CAL)
Electrons: 1 GeV – 20 TeV
Gamma-rays: 10 GeV – 10 TeV
(a few GeV – 10 TeV)
Protons and Heavy ions: (~10 GeV – 1 PeV)
CALET Gamma-ray Burst Monitor (CGBM)
Hard X-ray Monitor (HXM): 7 keV – 1 MeV
Soft Gamma-ray Monitor (SGM): 100 keV – 20 MeV
CALET
(port#9)
©JAXA
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High energy astro

5. CAL (CALorimeter) Gamma-ray performance CHD (Charge Detector):
(Charge measurement: Z=1-40)
IMC (Imaging Calorimeter):
(Arrival direction and event ID)
TASC (Total Absorption Calorimeter):
(Energy measurement and event ID)
1 TeV electron shower (simulation)
Gamma-ray performance
CALET simulation (>10 GeV; 3 year)
CAL
Energy range (photon)
10 GeV-10 TeV
Effective area
600 cm2 10 GeV)
Angular resolution
GeV
FOV
~2 sr
Crab
Vela
Galactic diffuse
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High energy astro

6. CALET Gamma-ray Burst Monitor (CGBM)
Hard X-ray Monitor (HXM)
Soft Gamma-ray Monitor (SGM)
HXM
SGM
Detector (Crystal)
LaBr3(Ce)
BGO
Number of detector 2 1
Diameter [mm] 61
102
Thickness [mm]
12.7 76
Energy range [keV]
7-1000
Energy keV
~3%
~15%
Field of view
~3 sr
~2p sr
100
HXM x 2
Effective area [cm2] 10
SGM 1
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High energy astro 10
100
1000
10000
Energy [keV]

7. CALET GRB Observation On-board CGBM trigger response:
Stored the CGBM event data
Lower the energy range of CAL to ~1 GeV
Capture two optical images by ASC
CAL
CGBM
ASC
Energy range
1 GeV – 10 TeV
(10 GeV – 10 TeV)
HXM: 7 keV – 1 MeV
SGM: 100 keV – 20 MeV A
Angular resolution
2.5o 1 GeV)
0.35o 10 GeV) -
~1”
Field of view
~2 sr
HXM: ~ 3 sr
SGM: ~ 2p sr
18.4o x 13.4o
Time resolution
62.5 ms
GRB trigger: 62.5 ms (event data)
Regular: 125 ms (8 ch), 4 s (512 ch)
0.5 s x 2
[8.6 mag (R)]
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High energy astro

8. CGBM Operation Status Scientific observation: October 6, 2015
Observation efficiency: ~60% (HV-on time)
On-board trigger alert (GCN notice) (
Alert rate: 15 alerts/month
Only send alert when we have a connection to ISS (~70% of time)
Light curves are available at
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High energy astro

9. GRBs Observed by CGBM
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High energy astro

10. CGBM GRB light curve gallery
GRB151006A
GRB151015A
GRB151107B
GRB151210B
GRB151212B
HXM keV
HXM keV
HXM keV
SGM keV
HXM keV
HXM keV
SGM keV
SGM keV
SGM keV
GRB151225A
GRB151227B
GRB151231A
GRB160101A
SGM keV
HXM keV
HXM keV
HXM keV
SGM keV
SGM keV
SGM keV
GRB160106A
GRB160107A
GRB160118A
GRB160223B
HXM keV
HXM keV
HXM keV
SGM keV
HXM keV
HXM keV
HXM keV
SGM keV
SGM keV
SGM keV
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High energy astro

11. CGBM GRB Statistics 49 GRBs (including 4 possible GRBs)
GRB rate: ~48 GRBs/yr
40 long GRBs (82%), 9 short GRBs (18%)
Simultaneous GRB detection by:
Fermi-GBM: 76% (31 GRBs)
Swift-BAT: 30% (12 GRBs; including GRBs with outside the field of view of BAT)
Konus-Wind: 49% (20 GRBs)
MAXI-GSC: 10% (4 GRBs)
3 known-z GRBs (160509A: z=1.17, A: z=0.367, B: z=1.406)
(Fermi-GBM: 82% long GRBs, 18% short GRBs (Paciesas et al. 2012)
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High energy astro

12. T90 Duration Distribution6
CGBM keV 4 2
100
BATSE keV 50
Number of GRBs
Fermi-GBM keV
200
100
Swift-BAT keV
100 50
0.001
0.01
0.1 1 10
100
1000
T90 [s]
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High energy astro

13. T90 Duration Distribution6
CGBM keV 4 2
100
BATSE keV 50
Number of GRBs
Fermi-GBM keV
200
100
Swift-BAT keV
100 50
0.001
0.01
0.1 1 10
100
1000
T90 [s]
Both short and long GRBs are detected (similar fraction to Fermi-GBM).
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High energy astro

14. T90 Duration Distribution6
CGBM keV 4 2
100
BATSE keV 50
Number of GRBs
Fermi-GBM keV
200
100
Swift-BAT keV
100 50
0.001
0.01
0.1 1 10
100
1000
T90 [s]
Both short and long GRBs are detected (similar fraction to Fermi-GBM).
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High energy astro

15. T90 Duration Distribution
Comparison of the effective area
T90 duration has a strong instrumental effect.
GRB A
SGM High ( keV)
SGM Low ( MeV)
Fermi-GBM NaI ( keV)
Rate [c/s]
Fermi-GBM BGO (0.1 – 50 MeV)
(Meegan et al.)
Swift-BAT ( keV)
Time since the trigger [s]
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16. T90 Duration Distribution6
CGBM keV 4 2
100
BATSE keV 50
Number of GRBs
Fermi-GBM keV
200
100
Swift-BAT keV
100 50
0.001
0.01
0.1 1 10
100
1000
T90 [s]
Both short and long GRBs are detected (similar fraction to Fermi-GBM)
The shorter T90 for long GRBs (tip of the iceberg effect?)
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High energy astro

17. Energy fluence vs. T90 duration
CGBM triggered Fermi-GBM GRBs
Fermi-GBM GRBs
5 Crab
(= 1.9 x 10-7 erg/cm2/s)
1 Crab
(= 3.8 x 10-8 erg/cm2/s)
Energy fluence ( keV) [erg cm-2]
6 x 10-7 erg/cm2
T90 duration [sec]
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High energy astro

18. 64 ms peak photon flux [ph cm-2 sec-1]
Peak flux vs. T90 duration
CGBM triggered Fermi-GBM GRBs
Fermi-GBM GRBs
64 ms peak photon flux [ph cm-2 sec-1]
( keV)
10 ph/cm2/s
(~16 Crab)
3 ph/cm2/s
(~5 Crab)
T90 duration [sec]
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19. Other Transient Events
Short bursts from SGR
Solar flares
SGM keV
HXM 7-10 keV
2016/6/20
15:16:34.8
HXM keV
2016/6/23
21:20:46.3
Rate [c/s]
Rate [c/s]
HXM keV
2016/6/24
10:22:09.3
HXM keV
Time since the trigger [sec]
Time since 7/18/2016 8:12:07 [sec]
11/30/16
High energy astro

20. CAL Gamma-ray Performance
Gamma-ray signal search for GW by CAL (Andriani et al. 2016)
CAL effective area in this analysis
Gamma-ray event selection
600
Good shower characteristics
No Hits in CHD and at the top IMC Layer
>1 GeV
0 < q < 5o
17.5o < q < 22.5o
27.5o < q < 32.5o
500
Simulation
400
Effective area [cm2]
300
CHD
200
IMC
100
CAL all sky map
TASC
Energy [GeV]
CAL all sky map
2015/10/13 – 2016/05/31
Fermi-LAT (on-axis)
Preliminary
> 1 GeV
Geminga
Galactic Latitude
Crab
(Note: non-uniform exposure)
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High energy astro
Galactic Longitude

21. Summary: CALET
CALET started its scientific observation since October 2015.
CGBM detected 49 GRBs as of today (detection rate of 48 GRBs/yr).
82% long GRBs and 18% short GRBs (similar to Fermi-GBM).
CGBM fluence GRB sensitivity is ~6 x 10-7 erg/cm2 ( keV).
CGBM peak flux GRB sensitivity is ~3 ph/cm2/s1 ( keV) for long GRBs and ~10 ph/cm2/s1 ( keV) for short GRBs.
CGBM spectral calibration and CAL gamma-ray analysis for GRBs are on-going.
11/30/16
High energy astro

22. MAXI Observations of GRBs
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23. Highlight of MAXI Transients
(Negoro et al. 2016)
Atel & GCN reported numbers
BHC: 6 (new), 6 (known)
NS LMXB: 4 (new), 13 (known)
Pulsar: 1 (new), 18 (known)
SFXT: 0 (new), 2 (known)
WD: 1 (new), 0 (known)
Stars: 21
AGN: 6
GRB: 63
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High energy astro

24. MAXI/GSC Performance Performance Energy range: 2-30 keV
FOV: 3 deg x 160 deg
(horizontal and zenith directions)
Typical transit time: s
Maximum effective area: 20 cm2
Position accuracy:
o (radius) + 0.1o (sys)
( o) x ( o) (box) + 0.1o (sys)
Same FOV
point source:
Operation
GSC operates between latitude ± 40 deg
(avoid a risk of discharge to carbon wires)
Operation efficiency: 80% %
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High energy astro

25. GRB Prompt Emission Spectrum
GRB A
Epeak
E-0.5
(E-2.5) E
(E-1)
nFn
Band function (Band et al. 1993)
Energy [keV]
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26. X-Ray Flashes (XRFs) (Ginga and BeppoSAX era)
Ginga (Strohmayer et al. 1998)
WFC / BATSE (Kippen et al. 2002) 10
100
1000
Ep (keV)
Peak Flux P1024 (ph cm-2 s-1)
(22 GRBs)
Number of Events 1 2 3 4
log Ep [keV]
XRFs: “Gamma-ray” bursts which emits most of the emission in X-rays
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High energy astro

27. HETE XRFs HETE-2 Epeak Distribution (Sakamoto et al. )
2- 5 keV
XRF
HETE-2 Epeak Distribution
(Sakamoto et al. )
5- 10 keV 10
39 Samples
BATSE GRBs 8
30 keV
keV 6
Count rate [c/s]
Number of Events 4
6- 40 keV 2
6- 80 keV
Log (Epeak) [keV]
keV
Broad Epeak distribution, extension to the low energy range
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High energy astro
Time [s]

28. MAXI GRB Catalog 35 GRBs 15 GRBs (~40%) (4 known-z GRBs)
(Serino et al. 2014)
From August 15, 2009 to middle of 2013:
35 GRBs
15 GRBs (~40%) (4 known-z GRBs)
Simultaneously observed by other GRB instruments
(Fermi-GBM/LAT, Konus-Wind, Swift/BAT, INTEGRAL)
(Excluding unID transients in galactic latitude ±10 deg.)
25 GRBs (~60%):
MAXI only detection
MAXI/GSC GRB rate: ~ 10 GRBs/yr
Typical delay time in sending MAXI GSC location to the community (e.g., GCN)
2 hours - a few days
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High energy astro

29. GRB Light curve and Spectrum
GRB (1s bin)
GRB (MAXI/GSC+Fermi/GBM)
Fermi/GBM
MAXI/GSC
GRB (MAXI/GSC+Swift/BAT)
MAXI/GSC
Swift/BAT
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High energy astro

30. MAXI XRF 100315A No obvious emission above 10 keV Hardness ratio
(8-20 keV) / (2-8 keV)
= 0.25 ± 0.13
4-10 keV
(Epeak < 5 keV)
10-20 keV
No obvious emission above 10 keV
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High energy astro

31. Hardness Ratio vs. Flux MAXI GRBs are weak and soft. 8-20 keV 2-8 keV
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High energy astro

32. log N-log F of MAXI GRBs
All GRBs
MAXI+others
MAXI only
Similar results in HETE-2 GRB sample (Sakamoto 2004)
11/30/16
The distance of XRFs can be closer to the Euclidean space.
High energy astro

33. log N – log P of HETE XRFs 20 (Sakamoto Ph.D. thesis) 10 XRF
GRB (Ep > 50 keV) 5
N (>P)
P -3/2 2 1 1 10
100
P keV (ph cm-2 s-1)
11/30/16
The distance of XRFs are close to the Euclidean space.
High energy astro

34. log N-log F of MAXI GRBs
All GRBs
MAXI+others
MAXI only
F-3/2
Similar results in HETE-2 GRB sample (Sakamoto 2004)
11/30/16
The distance of XRFs can be closer to the Euclidean space.
High energy astro

35. MAXI Unidentified Short Soft Transient (MUSST)
11/30/16
High energy astro

36. What is MUSST? Unidentified X-ray source
> 0.1 Crab in flux at detection, but only detected in a single GSC scan
Only detected by MAXI (no detection by other satellite)
No X-ray counterpart found by Swift/XRT follow-up observations
11/30/16
High energy astro

37. MUSST List Name (RA, Dec) T0 (MAXI) MAXI T0 2-20 keV Flux
Swift ToO Time
Swift/XRT 3 s UL
keV Flux 1
MAXI J
( , )
:40:57
1.3 x 10-8
T0+1.7 hour
1.9 x 10-12
(2.3 x 10-12) 2
GRB C
(60.247, )
:24:15
4.9 x 10-9
T0+4.5 hour
1.1 x 10-12
(1.6 x 10-12) 3
MAXI J
( , )
:18:16
3.1 x 10-9
T0+2.0 day
9.3 x 10-13
(1.1 x 10-12) 4
GRB A
( , )
:12:31
7.1 x 10-9
T0+6.3 hour
4.4 x 10-13
(4.7 x 10-13) 5
MAXI J
(86.44, 4.32)
:25:54
6.2 x 10-9
T0+1.1 day
2.2 x 10-12
(3.3 x 10-12) 6
GRB A
(248.10, 10.51)
:37:01
5.2 x 10-9
T hour
3.8 x 10-13
(4.4 x 10-13) 7
MAXI J
(247.83, )
:12:38
3.7 x 10-9
4.6 x 10-13
(6.1 x 10-13)
Flux in the unit of erg/cm2/s.
Swift/XRT upper limit is in the observed flux and the flux in the parenthesis is unabsorbed flux.
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High energy astro

38. MUSST GSC Localization and Swift/XRT Tiling Observation
MAXI J
GRB C
MAXI J
XRT field of view
33’
MAXI error region
GRB A
MAXI J
GRB A
MAXI J
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High energy astro

39. X-ray Upper Limit by Swift/XRT Follow-up Observations1 2 3 4 5 6 7
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High energy astro

40. Flux vs. Hardness of MUSST
HETE GRB
HETE XRF
MAXI + Others
MAXI only
MUSST
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41. MUSST is similar to XRFs
(Sakamoto et al. 2008)
- XRFs have a lower X-ray afterglow flux/luminosity comparing to C-GRBs.
Similar trend to what XRT upper limits are suggesting for MUSST.
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High energy astro

42. Summary: MAXI MAXI GRBs MUSST MAXI/GSC GRB rate: ~10 GRBs/yr
2/3 of MAXI GRBs (MAXI only detection) have a soft spectrum (no emission above 10 keV)
MAXI only soft GRBs shows a similar log N- log F distribution to that of HETE-2 XRFs (closer to -2/3 slope)
MUSST
7 MUSST ( )
Swift/XRT X-ray UL suggests MUSST is populated at a low X-ray afterglow flux region (if MUSST is associated to GRBs)
MUSST ~ XRFs?
11/30/16
High energy astro

43. CALET-MAXI simultaneously observed GRBs
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High energy astro

44. Field of view of MAXI and CGBM
MAXI GSC
MAXI SSC
Paddle
SGM: 2 pi str: deg^2
MAXI/GSC: 3 deg x 160 deg = 480 deg^2
 FOV fraction (SGM/GSC) = 43: バッチリ FOV が合うのは年間 1個
FOV of HXM
FOV of SGM
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High energy astro

45. Four MAXI-GSC and CGBM Simultaneously Detected GRBs
GRB A
GRB A
MAXI/GSC 2-4 keV
MAXI/GSC 2-4 keV
Rate [c/s]
Rate [c/s]
CGBM keV
(HXM)
CGBM 7-10 keV
(HXM)
Time since trigger [s]
Time since trigger [s]
GRB A
GRB A
MAXI/GSC 2-4 keV
MAXI/GSC
2-4 keV
Rate [c/s]
Rate [c/s]
CGBM keV
(SGM)
CGBM 7-10 keV (HXM)
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High energy astro
Time since trigger [s]
Time since trigger [s]

46. GRB 160101A Trigger time: CGBM: 2016-01-01 00:43:54 (UT)
MAXI: :43:52 (UT)
Also triggered Fermi-GBM/Konus-Wind
S (20 keV – 10 MeV): 1.5 x 10-5 [erg/cm2]
Epeak ~ 140 keV
Swift ToO observation (T – T ks)
One X-ray AG candidate
MAXI/GSC 2-4 keV
MAXI/GSC 4-10 keV
MAXI/GSC keV
CGBM/HXM
keV
Rate [c/s]
MAXI-GSC spectrum (1 scan; time-averaged)
CGBM/HXM
keV
Single power-law
CGBM/HXM
keV
alpha = -0.9 ± 0.1
CGBM/HXM keV
Time since trigger [s]
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High energy astro

47. GRB 160101A: Energy-resolved T90 duration
GRB (Crew et al. 2003)
T90 ~ E-0.40
T90 ~ E-0.44
MAXI-GSC
T90 [s]
CGBM
Fenimore relation:
Pulse-width ~ E-0.40
(Fenimore et al. 1995)
Energy [keV]
11/30/16
High energy astro

48. GRB 160107A: Pre-burst emission
MAXI detection: T0 (CGBM) - 45 s
MAXI/GSC spectrum:
Highly absorbed power-law
NH = (6 ± 3) x 1022 cm-2
alpha = -3.0 ± 0.7
Blackbody
kT = 1.3 ± 0.2 keV
MAXI-GSC 2-4 keV
MAXI-GSC 4-10 keV
MAXI-GSC keV
HXM 7-10 keV
HXM keV
Rate [c/s]
HXM keV
HXM keV
HXM keV
SGM keV
SGM keV
Rate [c/s]
SGM keV
Time since trigger [s]
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High energy astro
Time since trigger [s]

49. Pre-burst Emission & Quiescent Period
Yamazaki 2009
BAT survey data search (Lien et al. 2016)
1 possible detection (4.7 s) / 794 GRBs
No bright pre-burst emission found in the BAT data.
X-ray emission at the quiescent period
GRB A
BAT keV
Rate [c/s/det]
XRT keV
Alpha = ± 0.15
Flux [erg/cm2/s]
If a true burst T0 is few hours before the instrument oriented T0, the shallow decay seen in XRT is no longer shallow (close to normal decay).
Time since BAT trigger [s]
High sensitive wide-field soft X-ray survey!!
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High energy astro

50. Summary: CALET-MAXI GRBs
Four GRBs (GRB A, GRB A, GRB A and GRB A) are simultaneously detected by CGBM and MAXI/GSC.
GRB A: keV broad-band GRB prompt light curve is available.
GRB A: MAXI/GSC detected the emission 45 s prior to the main GRB episode.
11/30/16
High energy astro

51. GRB conference 2018? in Japan
At Huntsville GRB conference, Valerie Connaughton (LOC, SOC) asked me for a possibility of organizing GRB conference (two years from now) in Japan.
Yokohama Multi-messenger GRB 2018?
11/30/16
High energy astro

52. FRB 131104: Re-visit Swift/BAT data
11/30/16
High energy astro

53. 12th Anniversary of Swift!!
Launch: November 20, 2004 (12th year on-orbit!)
2016 NASA senior review: Swift ranked No. 1!!
>1000 GRBs detected (~90 GRBs/yr) (Lien et al. 2016)
No hardware issue
“Many more years of discovery with Swift!!” (Neil Gehrels)
11/30/16
High energy astro

54. Hard X-ray Counterpart of FRB 131104?
11/30/16
High energy astro

55. BAT Image Analysis Flux mask (default) Detection mask
Sky image using the flux mask
Sky image using the detection mask
FRB position
FRB position
11/30/16
High energy astro

56. BAT 64 ms Raw Light Curve
BAT keV
BAT keV
BAT keV
No excess signal in the BAT raw 64 ms light curve
BAT keV
11/30/16
High energy astro

57. BAT 1.6 s Light Curve (quad-rate)
BAT mask shadow of FRB direction
Quad0
Quad1
Quad1
Quad2
Quad3
Quad2
Partial coding fraction: 6% coding
Quad3
11/30/16
High energy astro

58. BAT Survey Data Analysis
14-24 keV
24-50 keV
No significant detection around T0 in the BAT survey data.
keV
keV
11/30/16
High energy astro

59. BAT Scaled Map Analysis
15-50 keV
Rate [c/s/det]
Time since 18:03: UTC [s]
11/30/16
High energy astro

60. Summary: BAT FRB
The BAT detection claim of the hard X-ray counterpart of FRB is not convincing.
The position was extremely partial coded FOV which requires a full coded mask to generate the image (not recommended in a standard analysis).
Doesn’t show any excess in the raw light curve. Furthermore, no excess in the light curve of quadrant#3 (inconsistent with the mask image).
The light curves generated by the image analysis (survey data and scaled map data) are both consistent with zero flux around the FRB trigger time.
11/30/16
High energy astro