Swift and CALET による非電磁波(ニュートリノ)
アラートのフォローアップ観測
T. Sakamoto (AGU),
P. Evans (U of Leicester)Contentsl Swiftl Introduction of Swiftl Unique Swift’s characteristics
l Follow-up IceCube alerts (2011-2014)l Follow-up ANTARES alerts
l Follow-up real-time IceCube alerts (2016-)
l IceCube-160217: Triplet eventl CALETl Introduction of CALETl Search for EM counterpart of IceCube events
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GRBs as the sources forUHECR?
(Aartsen+ 2017, astro-ph/1702.06868)

IceCube:508 GRBs (Northern Hemisphere), 664 GRBs (Southern Hemisphere)γ
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Why X-ray?
(Question) Find the afterglow of GRB 161219B
X-ray (Swift/XRT)

3/2/17

Optical (Swift/UVOT)

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Why X-ray?
(Question) Find the afterglow of GRB 161219B
X-ray (Swift/XRT)

3/2/17

Optical (Swift/UVOT)

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Swift20043/2/17

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Swift Gamma-ray Burst
Explorer MissionlNASA’s Medium-Class Explorers (MIDEX)
Jan 1999: Selected for Phase A studyl Oct 1999: Selected for flightl Nov 2004: Launchll

International collaboration (mainly US, UK and Italy)
Burst Alert Telescope (BAT): New development at NASA/GSFC andLANL
l X-ray Telescope (XRT): Mirror (JET-X FM unit), CCD (XMM-Newton
EPIC MOS); PSU, INAF and ULl Ultra-Violet/Optical Telescope (UVOT): Copy of XMM-Newton OM;
PSU and MSSLll

Successful mission extensionl
3/2/172016 NASA Astrophysics Senior Review ranked #1!
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7UV/Optical Telescope (UVOT)

Burst Alert Telescope (BAT)

Aperture: 30 cm (XMM OM)
Det: MCP+CCD (XMM OM)
FOV: 17’ x 17’
7 filters (UV - Opt)+2 grism

UVOT

XRT

Mask

X-Ray Telescope (XRT)128 CZTBAT
E_range: 15-150 keV (15-350 keV)
Det: CdZnTe (4 x 4 x 2 mm3)
# of detectors: 32,768 (256 x 128)
FOV: 120 deg x 90 deg
Pos: 1’-3’

E_range: 0.3-10 keV
Focal Length: 3.5m
Det: X-ray CCD (XMM MOS)
FOV: 23’ x 23’

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Fully Automated Observations
Observations of afterglows right off the bat (no human in the loop).

XRT & UVOT Observation(T0+75-120 s)
T0+(20-75 s)
BAT GRB detection: T0
BAT GRB position: T0+~20 s (3’)
Images: GRB 080319B

Gamma-ray Image (BAT) X-ray Image (XRT)BAT 3’ position

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Optical Image (UVOT)XRT 5” position9

Automatic Swift GRB Observation (GRB 080319B)
Report BAT pos
to the ground(3’)

NFI observation
start
Report XRT pos
to the ground (5”)

Slew start

3/2/17

Slew end

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UVOT pos(T+22 min)10

Swift Operation and Available Datal BAT on-board triggerl Automatic XRT/UVOT Observations (T0+~100s)l BAT event data (T0-250 s – T0+1000 s)l Target of Opportunity (ToO) observationl Fast ToO is possible (within an hour)l New X-ray (XRT) and UV/optical (UVOT) data of thefieldl Possible tiling observation
l Regular operationl BAT: raw light curve data (64 ms, 1.6 s), scaled map

data and survey data
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Challenges for non-EM
Counterpart Searchl Large error region (~scale of degrees)
BATXRT

UVOT

120o60o

FOV: EnoughSensitivity: Not good(~10-9 erg cm-2 s-1)

24’17’

FOV: Not enough
FOV: Not enoughSensitivity: Good
Sensitivity: Good (~20 mag)(~5 x 10-14 erg cm-2 s-1)

l When is the good time to search?
l Strongly depends on the physical source

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Automatic Tiling Observation
Automatic tiling observation capability(Part of the BAT on-board software)- Try to observe all N tiles in the first orbit- Continue observing until the requested observing time (min exp/tile = 60 s)

Tiling patterns
4-tiling(figures from J. Kennea)

7-tiling

19-tiling

Required tiling pattern
to cover 1o diameter3/2/17

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37-tiling

Required tiling pattern
to cover 2o diameter13

2011 March – 2014 August
IceCube 20 doublet triggers(Evans+, 2015)• 7 tiling observations to cover the IceCube 50% error radius(typically 0.5o)• Typically within 5 hours from the IceCube trigger time
• Typical exposure per tile is 1-2 ksec• Sensitivity: 6-10 x 10-13 erg cm-2 s-1 (more sensitive thanthe ROSAT All Sky Survey: 2.8 x 10-12 erg cm-2 s-1)

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IceCube 20 doublet triggers(Evans+, 2015)

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IceCube 20 doublet triggers
This source was found in
XRT follow up of an
IceCube trigger.

And turned out not to
be a transient.
Not all fading objects
are the counterpart.

(Evans+ 2015)
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IceCube 20 doublet triggers
In follow up of 20 doublet triggers, XRT detected 119
sources, only 30 of which were previously catalogued Xray sources (Evans+ 2015).
The lack of a ‘smoking gun’ counterpart doesn’t mean wedidn’t find one, just that we didn’t find one that looks likewe expected.

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Follow-up ANTARES triggers
••
•
•
•

ANTARES triggered Swift, ROTSE and TAROT.
42 with optical follow up (ROTSE/Tarot)
7 with X-ray follow up (XRT).
Combination of multiplet triggers, or single high-energy events.
No counterparts were found in any wavelength (Adrián Martínez+2016). Suggests the neutrino were not from GRBs.
(Martinez+ 2016)
Optical afterglow
X-ray afterglow

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Real-time IceCube Alert-Trigger Time Type

Position

Error(50% radius)

XRT
follow-up

BAT FOV?

2016-07-31
01:55:04.00

HESE/
EHE

(215.109,-0.458)

20.99’

Yes

T0+175 s

2016-08-06
12:21:33.00

EHE(122.798,-0.733)

6.67’

No

T0+1.0 hr

2016-08-14
21:45:54.00

HESE(199.310,-32.016)

28.79’

No

T0+1.1 hr2016-11-03
09:07:31.12

HESE(40.874,+12.615)

39.00’

Yes

T0+21.4 min

2016-12-10
20:06:40.31

EHE(45.854,+15.785)

14.99’

NoT0+3.9 hr

HESE: High Energy Starting Event; a single-neutrino with an energy in the sub-PeV to 1 PeV
EHE: Extremely High Energy; a single-neutrino with an energy higher than several hundred TeV
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IceCube-160731:
BAT Prompt Data
BAT 64 ms raw light curve

BAT 15-150 keV sky image

15-25 keV

25-50 keV

IceCube-160731
error circle (50%)

50-100 keV

15-100 keVSpacecraft Slew

3/2/17- No significant emission in the 64 ms
light curve data (T0+175 s – T0+250 s)- No unknown source in the BAT sky
image (T0+185 s – T0+462 s) at >5 σ
- 5-σ 15-150 keV UL: 3 x 10-9 erg cm-2 s-1(assuming E-2; 300 s exposure)

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IceCube-160731:
XRT/UVOT Follow-up(Evans+ 2016, GCN Circ. 19747)- 19 tiling observation (800 s per tile)- T0+3.9 ks to T0+46.5 ks- Six X-ray sources (all ID)- Two stars- Three quasars- One known XRT source- No transient sources in UVOT
- 3-σ X-ray UL: (3.1-4.3) x 10-13 erg
cm-2 s-1 (0.3-10 keV; typical AGNspectrum)- 3-σ optical UL: 18 mag (u)3/2/17

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IceCube-161103:
XRT Follow-up(Evans+ 2016, GCN Circ. 20125)- 19 tiling observation (150-250 s pertile)- T0+17.5 ks to T0+35.5 ks- Four X-ray sources (all un-ID), but
all faint (fainter than the RASSlimits)- 3-σ X-ray UL: (8.1-12) x 10-13 erg
cm-2 s-1 (0.3-10 keV; typical AGNspectrum)

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IceCube-160217: Triplet event(Aarten+ 2017, astro-ph/1702.06131)- T0: 2016-02-17 19:21:31 (arrivaltime of the first event)- All three events arrived within
less than 100 s- Swift-BAT, Fermi-LAT, HAWC
- Swift-XRT/UVOT, ASAS-SN,LCO, MASTER, VERITAS

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IceCube-160217: Triplet event
XRT/UVOT Follow-up(Aarten+ 2017, astro-ph/1702.06131)- 37 tiling observation (300-400 s pertile)- T0+ 22.6 hr – T0+1.2 day- Six X-ray sources (one un-ID)- One AGN
- Four stars- No transient sources in UVOT
- 3-σ X-ray UL: (6.3-8.9) x 10-13 erg
cm-2 s-1 (0.3-10 keV; typical AGNspectrum)- 3-σ optical UL: 17.4 mag (u)3/2/17

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IceCube-160217: Triplet event
Un-ID X-ray source X6
Follow-up XRT observations of X6:T0+ 29 day (1 ks) and T0+156 day (8.6 ks)

Keck/LRIS image

S2: G2 Star

S1: G/F StarXRT (90%)- t-0.5 decay (over 5 months)
Unlikely to be a GRB afterglow
3/2/17

X6: Stellar flare? Distance AGN?
But unlikely related to the
IceCube-160217

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CALET(CALorimetric Electron Telescope)

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CALET(CALorimetric Electron Telescope)
Observatory of high energy electrons
and gamma-rays

CGBM/HXM- Observa)on of high energy cosmic-rays- All sky gamma-ray survey (> 10 GeV)- High energy transients (GRBs, SGRs, …)

MAXICALET(port#9)
3/2/17

CGBM/SGMASCCALScien)ﬁc instruments:- CALorimeter (CAL)- Electrons: 1 GeV – 20 TeV- Gamma-rays: 10 GeV – 10 TeV(1 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©JAXA- SoR Gamma-ray Monitor (SGM): 100 keV – 20 MeV
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CALET
Gamma-ray Burst Monitor (CGBM)
SoD Gamma-ray Monitor (SGM)

HXM

SGM

Detector (Crystal)

LaBr3(Ce)BGO

Number of detector

21

Diameter [mm]61102

Thickness [mm]12.776

Energy range [keV]

7-1000100-20000

Energy resolu)on@662 keV~3%~15%

Field of view

~3 sr~2p sr

3/2/17100

Effective area [cm2]Hard X-ray Monitor (HXM)

HXM x 2

101
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SGM

10100

1000

Energy [keV]

10000

2828

CGBM Observation Efficiency

HV-on time: ~60%
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Summary of IceCube Event
Search by CGBM-Trigger Time

TypeCommentGCN

2016-07-31
01:55:04.00

HESE/EHE

Below horizon-

2016-08-06
12:21:33.00

EHE

HV-off-

2016-08-14
21:45:54.00

HESE

HV-off-

2016-11-03
09:07:31.12

HESE

Non-detection

20162

2016-12-10
20:06:40.31

EHE

Non-detection

20253

HESE: High Energy Starting Event; a single-neutrino with an energy in the sub-PeV to 1 PeV
EHE: Extremely High Energy; a single-neutrino with an energy higher than several hundred TeV
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IceCube-161103(Kawakubo et al. GCN Circ. 20162)

0.125 s bin light curve
SGM: 40-100 keVRate [c/s]SGM: 100-230 keV

HXM
SGM

SGM: 230-450 keV

SGM: 450-1000 keV

7 sigma upper limit (50-1000 keV; 1 s):- 5.0 x 10-7 erg cm-2 s-1 (assuming E-2)

Time since the trigger [s]No significant emission >4.2 σ
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IceCube-161210(Kawakubo et al. GCN Circ. 20253)

0.125 s bin light curve
SGM: 40-100 keVRate [c/s]SGM: 100-230 keV

HXM
SGM

SGM: 230-450 keV

SGM: 450-1000 keV

7 sigma upper limit (50-1000 keV; 1 s):- 5.6 x 10-7 erg cm-2 s-1 (assuming E-2)

Time since the trigger [s]No significant emission >3.1 σ
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1-s Peak photon flux (10-1000 keV) [ph cm-2 s-1]

Comparison to GRBs
Fermi-GBM

IceCube-161210
IceCube-161103

T90 [s]3/2/17

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Summaryl EM counterpart search based on the alert

from neutrino detectors has just began.
l No success for identifying the EM
counterpart of neutrino events.
l Space observatories such as Swift andCALET are ready to follow-up neutrinoevents.

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