Multi-Messenger Astronomy
with Swift
T. Sakamoto (AGU)(Special thanks for Phil Evans)
SwiftContentsn Introduction of Swiftn Gravitational-wave (GW) electromagnetic(EM) counterpart search– Short GRBs
– Swift GW EM counterpart search strategy
during O2– GW170817

n High-energy neutrino EM counterpart
search during 2017
3/26/18

Multi-messenger Astro 2018 @ ChibaU

2SwiftSwift20043/26/18

Multi-messenger Astro 2018 @ ChibaU

3SwiftThe Neil Gehrels Swift Observatory
The Swift Gamma-Ray Burst Explorer has officially beenrenamed the Neil Gehrels Swift ObservatoryNeil Gehrels (1952-2017)

3/26/18

Brad Cenko: Swift PI

Multi-messenger Astro 2018 @ ChibaU

4Swift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’

SwiftCharacteristics of Instruments
Field of view

BAT120o
60o

XRT
24’

UVOT

Typical Sensitivity~10-9 erg cm-2 s-1(15-150 keV)

Prompt dataaround T0

5 x 10-13 erg cm-2 s-1(0.3-10 keV; 1 ksec)

Follow-up~20 mag (v; 200 s)

Follow-up

17’

6

Swift

Why Swift for ToO Observations?
Chandra call for proposals handbook (page 37)

3/26/18

Multi-messenger Astro 2018 @ ChibaU

7SwiftAlways Fast ToO
GRBObserving scheduleAutomatically changes
the observing schedule

1.
2.
3.
4.

1.
2.
3.
4.

BAT detects GRB!

ToOToO(GW170817)

Crab nebula
A0535
Mrk 421….

TDRSS

Observing Schedule
1.
2.
3.
4.

GRB
Mrk 421
Crab nebula….

Crab nebula
A0535
Mrk 421….

ToO(GW 170817)

Automatically changes
the observing schedule
1.
2.
3.
4.

GW 150914
A0535
Mrk 421….

Swift PI decides ToO approval
3/26/18

Multi-messenger Astro 2018 @ ChibaU

8

Swift

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 tocover 1o diameter
3/26/18

Multi-messenger Astro 2018 @ ChibaU

37-tiling

Required tiling pattern tocover 2o diameter
9

Swift

Gravitational-wave (GW)Electromagnetic (EM)Counterpart Search
Short GRBs
3/26/18

Multi-messenger Astro 2018 @ ChibaU

10SwiftLight curves of GRBs
HETE-2/FREGATECount rate [c/s]

GRB 020813

GRB 030329

GRB 020531

Time [s]3/26/18

Multi-messenger Astro 2018 @ ChibaU

11SwiftHardShort GRBs

rate

Two populations in GRBs
T90

5%Soft

BATSE 4B
(Paciesas et al. 1999)

95% time

Long GRBs
Duration

3/26/18

Multi-messenger Astro 2018 @ ChibaU

12

Swift

Prompt emission properties of Short GRBs
GRB 060313 (typical short GRB)

GRB 061006 (short GRB with E.E.)

0.74 s1.23 s129.9 s• With/without extended emission (E.E.) (Norris & Bonnell 2006)• No spectral lag (Norris et al. 2001)• Low fluence and high Epeak (Outlier of Epeak-Eiso relation) (Amati 2006)• No soft short GRBs (Kouveliotou 1993, Sakamoto 2006)
3/26/18

Multi-messenger Astro 2018 @ ChibaU

13

Swift

Long-lasting X-ray Emission in s-GRBs(Kisaka, Ioka, Sakamoto 2017)

Two distinct components in X-ray light curves
3/26/18- About a half of s-GRBs has
both EE and PE components- Universal X-ray emission
characteristics of s-GRBs?

Multi-messenger Astro 2018 @ ChibaU

14

Swift

S-GRB hosts and “kilonova” emission?
- Mixed (early-type/late-type) host galaxies

GRB 130603B (Tanvir et al. 2013)

GRB 050509B (Gehrels et al. 2005)‘kilonova’ association:Indication of NS-NS/NS-BH merger

S-GRB host galaxy
population(Berger 2014)

3/26/18

Multi-messenger Astro 2018 @ ChibaU

15

Swift

S-GRBs: NS-NS/NS-BH Merger Model
Eichler et al. 1989; Narayan, Paczynski & Piran 1992
(http://swift.sonoma.edu/resources/multimedia/animations/)

1. NS binary system

4. Merged
3/26/18

2. Getting close due to the energy loss by gravitational-wave

5. Remnant is BH with a disk
Multi-messenger Astro 2018 @ ChibaU

6. Lunch a GRB jet
16SwiftSwift O2-run Observing Strategyn Co-detection of a short GRB with BAT and the GW
signal from LIGO-Virgo (best case!)– 0.02-0.14 events per year (Wanderman & Piran 2015)

n Swift NFIs follow-up criteria– Unmodelled triggers: FAR < 1/6 months and P400 > 0.2(P400: the amount of convolved probability covered by thetop 400 Swift pointings)– CBC triggers: 1) “ContainsNS” > 0.25 or 2) “ContainNS”< 0.25 and P400 > 0.5

n If EM counterpart detected by other facilities, Swiftwill do follow-up
3/26/18

Multi-messenger Astro 2018 @ ChibaU

17SwiftAbbott et al. 2017

GW 170817
Gravitational-wave
event from BNSmerger!

3/26/18

Multi-messenger Astro 2018 @ ChibaU

18

Swift

Association of GW 170817 and GRB 170817A
GW 170817/GRB 170817A (Abbott et al. 2017) GRB 170817A (Goldstein et al. 2017)
IPN (Fermi-GBM/INTEGRAL)Earth

LIGO/Virgo

Fermi-GBM

T90 = 2.0 +- 0.5 s

Probability ofS-GRB class:72%

3/26/18

Multi-messenger Astro 2018 @ ChibaU

19SwiftFermi-GBM spectrum of GRB 170817A(Goldstein et al. 2017)

Main PeakCPL:
α = -0.62 +- 0.40
Epeak = 185 +- 62 keVMain pulse:
time-averaged flux: (3.1 +- 0.7) x 10-7 erg/cm2/s

3/26/18

Multi-messenger Astro 2018 @ ChibaU

Soft TailBB:kT = 10.3 +- 1.5 keV

20

Swift

GRB 170817: Fermi-GBM light curve
1s binning
NaI 1

NaI 2

NaI 5

3/26/18

Since
Fermi-GBM
Multi-messenger
Astro 2018trigger@ ChibaU time [s]

21

Swift

GRB 170817 50 ms Light curve ofINTEGRAL/SPI-ACS and Fermi/GBM
SPI-ACS (>100 keV)Counts/50 ms

NaI 1 (100-300 keV)

NaI 2 (100-300 keV)NaI 5 (100-300 keV)Time since the GW170817 trigger [s]
3/26/18

Multi-messenger Astro 2018 @ ChibaU

22

Swift

GW 170817: BAT Observation

1.6 s light curves(Evans et al. 2017)15-25 keVEarthBAT FoV
25-50 keV
50-100 keV

100-350 keV

15-350 keV

GW- Nothing in the BAT light curve atT0(GW)- GW 170817 error region wasocculted by the Earth-400-2000200400
3/26/18Time since the GW trigger [s]Multi-messenger Astro 2018 @ ChibaU

23

Swift

Insight-HXMT: GRB 170817 Observation(Li et al. 2017)

θ = 47.3 deg.

No detection- Consistent that GRB
170817 is very weak andsoft (3-sigma UL 10-1000
keV : 2 x 10-6 erg/cm2/s)
Konus-Wind: No detection
90% UL: 3 x 10-7 erg/cm2/s (~3 s)(Svinkin et al. GCN circ. 21746)
3/26/18

Multi-messenger Astro 2018 @ ChibaU

24

Swift

Swift Follow-up Observations(Evans et al. 2017)

1. T0+1 hr: 37 tiling at the center of the Fermi-GBM position
2. T0+4.6 hr: (LIGO single sky map + GWGC) & Fermi-GBM location
3. T0+7.4 hr: LIGO/Virgo three detector sky map + GWGC
4. T0+14.4 hr: Follow-up on EM 170817- UVOT detections in all filters, but no XRT detection
3/26/18

Multi-messenger Astro 2018 @ ChibaU

25

Swift

UVOT works!

(Evans et al. 2017)

SSS17aNGC 4993

Rapidly fading UV emissions
were detected by UVOT
Clear detection of kilonova in UV
3/26/18

Multi-messenger Astro 2018 @ ChibaU

26

SwiftChandra detection of X-rays from SSS17a(Troja et al. 2017)
Hubble (T0+1 day)

Chandra (T0+9 days)

NGC 4993

NGC 4993

T0:2.2 d: Non detection
T0+9 d : 12 photons: (4.0 +- 1.1) x 10-15 erg/cm2/s
T0+15 d: 17 photons: (5.0 +- 1.0) x 10-15 erg/cm2/s

Slowly rising: t0.5
3/26/18

Multi-messenger Astro 2018 @ ChibaU

27

Swift

Off-axis GRB Afterglow?
(Troja et al. 2017)
Jet opening angle:
θj = 15 deg
Viewing angle:
θv = 28 deg
Consistent with late-timerise in both X-ray and radio
Standard uniform jet:Prompt GRB emission
should be fainter than GRB
170817A
Gaussian jet:Consistent with the data

3/26/18

Multi-messenger Astro 2018 @ ChibaU

28

Swift

Swift/XRT Follow-up Observations of SSS17a• 2017/8/18 – 2017/9/1• 2017/9/12• 2017/12/1 – 2018/1/4

Total exposure: 305 ks
Swift/XRT

Chandra

SSS17aSSS17aNGC 4993

3/26/18

Multi-messenger Astro 2018 @ ChibaU

29

Swift

Chandra Further Observations(Only archived data)
2017/8/26 10:33:50 –2017/8/27 01:17:39 (49.4 ks)

2017/09/01 15:22:22 2017/09/02 04:53:25 (46.7 ks)

2017/12/03 01:39:54 2017/12/03 23:07:27 (74.0 ks)

2017/12/06 10:44:40 –2017/12/06 18:13:27 (24.7 ks)

2018/01/17 21:28:45 –2018/01/18 07:04:56 (31.7 ks)

2018/01/21 13:29:10 –2018/01/21 18:27:05 (15.9 ks)

2018/01/23 07:47:35 –2018/01/23 14:06:27 (20.8 ks)

2018/01/24 08:02:59 –2018/01/24 14:46:23 (22.2 ks)

2018/01/28 04:14:16 –2018/01/28 08:46:45 (14.2 ks)

3/26/18

Multi-messenger Astro 2018 @ ChibaU30

SwiftRATE (0.3-8 keV) [c/s]

SSS17a: Chandra X-ray Light curve

decay?

Time since GW170817 trigger [day]3/26/18

Multi-messenger Astro 2018 @ ChibaU

31

Swift

RATE (0.3-8 keV) [c/s]

SSS17a: Chandra X-ray Light curve

Gaussian-jet(Troja et al. 2018)
Time since GW170817 trigger [day]3/26/18

Multi-messenger Astro 2018 @ ChibaU

32

Swift

Hardness of SSS17aHardness(2.5-8 keV vs. 0.3-2.5 keV) RATE (0.3-8 keV) [c/s]

Chandra3/26/18

No indication of spectral evolution

Timesince GW170817
trigger [day]Multi-messenger
Astro 2018 @ ChibaU

33

Swift

Summaryn GW 170817– Swift observation• BAT: Occulted by the earth at T0(GW)• UVOT: Detection of kilonova emission• XRT: None detection of X-ray emission (Hint of anoff-axis GRB)

– Chandra observation• Late time rise (T0+9 days) in X-rays• Further Chandra observation is needed to see a decay
in X-ray flux

3/26/18

Multi-messenger Astro 2018 @ ChibaU

34

SwiftHigh Energy Neutrino
EM Counterpart Search

3/26/18

Multi-messenger Astro 2018 @ ChibaU

35

SwiftGRBs as the sources for UHECR?
(Aartsen+ 2017, astro-ph/1702.06868)

IceCube:508 GRBs (Northern Hemisphere), 664 GRBs (Southern Hemisphere)γ
3/26/18

Multi-messenger Astro 2018 @ ChibaU

ν36

Swift

Real time IceCube Alerts on 2017
Trigger Time

TypePosition

Error(50% radius)

XRT follow- BAT FOV?
up

2017-03-12
13:49:39.83

HESE(304.730,-26.238)

25.19’

T0+ 2.0 hr(T0+15.2 hr)

T0+ 0.7 hr

2017-03-21
07:32:20.67

EHE(98.326,-14.486)

19.48’

T0+ 6.6 hr(T0+7.2 hr)

T0+ 6.6 min

2017-05-06
12:36:55.80

HESE(221.675,-26.036)

25.19’

NoT0

2017-09-22
20:54:30.43

EHE(77.285,+5.752)

14.99’

T0+ 3.3 hr(T0+1.1 day)T0+ 25.6 s

2017-10-15
01:34:30.06

HESE(162.579,-15.861)

25.19’

No

T0+ 2.9 hr

2017-10-28
08:28:14.81

HESE(275.076,+34.501)

96.00’

No

T0+ 2.1 hr

2017-11-06
18:39:39.21

EHE(340.250,+7.314)

14.99’

T0+ 3.2 hr(T0+17.2 hr)

T0- 9.7 min

3/26/18

Multi-messenger Astro 2018 @ ChibaU

37Swift

IceCube-170312A
XRT(T0+7.3 ks – T0+54.9 ks; 19 tiling)(Keivani et al. 2017, GCN circ. 20890 )Five X-ray sources are detected
including one known X-ray source.
Four un-cataloged sources are well
below the ROSAT All Sky Survey
limit.
No new X-ray source (>3 sigma):
2.9 x 10-13 erg/cm2/s (0.3-10 keV)
(NH = 3 x 1020 cm-2; Γ=1.7)
0.8o

3/26/18

Multi-messenger Astro 2018 @ ChibaU

38

Swift

IceCube-170321A
XRT (Keivani et al. GCN circ. 20964)(T0+23.7 ks – T0+37.8 ks; 7 tiling)

BAT 14-195 keV sky image(T0+578 s - T0+1643 s)
Crab
IceCube-170321A

0.55o5-sigma UL (14-195 keV; Γ=2) :6.1 x 10-9 erg/cm2/s (@1065 s)
3/26/18

No new X-ray source (>3 sigma):
1.48 x 10-13 erg/cm2/s (0.3-10 keV)
3 x 1020 cm-2; Γ=1.7)
Multi-messenger Astro (N2018H@=ChibaU
39 SwiftIceCube-170506A
BAT 64 ms raw light curve

BAT 14-195 keV sky image(T0+5 s - T0+228 s)

15-25 keV

Sco X-1
IceCube-170506A(θ=39.5 deg)

25-50 keV

50-100 keV

100-350 keV

5-sigma UL (14-195 keV; Γ=2) :3.7 x 10-8 erg/cm2/s (@ 223 s)
3/26/18

Multi-messenger Astro 2018 @ ChibaU

40

Swift

IceCube-170922A
BAT raw 1.6 s light curve
15-25 keV

XRT (Keivani et al., GCN circ. 21930, 21941)(T0+11.7 ks – T0+92.9 ks)

25-50 keV

TXS 0506+056
50-100 keV

100-350 keV

Nine X-ray sources are detected including thecandidate blazar TXS 0506+056.
3/26/18

Multi-messenger Astro 2018 @ ChibaU

41

Swift

IceCube-170922A: Association ofblazar TXS 0506+056?

XRT 0.3-10 keV count-rate [c/s]Data from Swift/XRT Monitoring of Fermi-LAT Sources of Interest(www.swift.psu.edu/monitoring/ Stroh & Falcone 2013)

Day since IceCube-170922A trigger time [day]3/26/18

Multi-messenger Astro 2018 @ ChibaU

42

Swift

IceCube-170922A: Association of
blazar TXS 0506+056?

XRT 0.3-10 keV count-rate [c/s]Data from Swift/XRT Monitoring of Fermi-LAT Sources of Interest(www.swift.psu.edu/monitoring/ Stroh & Falcone 2013)

Day since IceCube-170922A trigger time [day]3/26/18

Multi-messenger Astro 2018 @ ChibaU43

SwiftIceCube-171106A
XRT(T0+11.5 ks – T0+62.0 ks; 19 tiling)

Keivani et al., GCN circ. 22115

WISE J224206.68+073148.3
87GB 223537.9+070825

3/26/18

Multi-messenger Astro 2018 @ ChibaU-14 X-ray sources aredetected.
5 sources are within theIceCube error region.
Two known blazars: 87GB223537.9+070825 and WISE
J224206.68+073148.3 arelocated inside the error
region.

44

SwiftSummaryn IceCube Events– Swift observations of five IceCube events– IceCube-170922A• X-ray flare from blazar TXS 0506+056
after the IceCube alert– IceCube-171106A• Two known blazars are inside theIceCube error region.
Swift will keep revolutionize MMA.
3/26/18

Multi-messenger Astro 2018 @ ChibaU

45

Swift

Gamma-ray Bursts in
the Gravitational Wave Era 2019
Targeting date: October - November 2019
Candidate place: Yokohama, Kanagawa
Funding support by Yamada Science Foundation
L. Amati, J.-L. Atteia, B. Cenko, V. Connaughton, J. Greiner, P. Meszaros, P. O’Brien,T. Piran, J. Racusin, L. Singer, N. Tanvir, E. Troja, W. Xiang-Yu, B. Zhang, K. Asano,
K. Ioka, N. Kanda, N. Kawai, K. Toma, Y. Fukazawa, K. Murase, R. Yamazaki, M. Yoshida,
D. Yonetoku
LOC: T. Sakamoto, M. Serino, S. Kisaka
Red Brick Warehouse

3/26/18

Multi-messenger Astro 2018 @ ChibaU46

Swift