K-band VLBI Observation ofMagnetar Radio Outburst

Contents
1. Why Magnetar Astrometry?
2. Observation and Analysis
3. Future Prospect

NAOJ SKA1 STUDY GROUP
国立天文台SKA1検討グループ
2019/9/3

Takuya Akahori
Group Scientist / Manager

SKA-Japanシンポジウム2019

11. Why Magnetar Astrometry?

Issues on Magnetar Hypothesis
nThe magnetar hypothesis explains
AXP and SGR well, but...
1. What is the origin of strong B?
n The standing accretion shock instability (SASI)
can induce dynamo at a supernova explosionn Hypothesis: SNR has a peculiar morphology?
n Method: Identify the progenitor SNR à
Measure the magnetar’s location and velocity

2. What is the trigger of outburst?
n Supernovae “kick” neutron starsn Violent (v = several x 100km/s) interaction withthe ISM may induce Alfvenic waves and impact
onto the magnetospheren Hypothesis: Magnetars have higher velocity?
n Method: Measure the magnetar’s velocity
2019/2/20

中性子星の観測と理論＠京大

Takiwaki-san’s Geppou
Enoto+192

1. Why Magnetar Astrometry?

Quiz
http://www.physics.usyd.edu.au/~bmg/fig_sgr_snr.gif

SNR HB9

τSNR=τSGR?
DSNR=DSGR?

Q: Is HB9
the progenitorof SGR0501?
1. Yes
2. No
3. Uncertain-vSGRτSGR=d0501+4516

2019/2/20vSGR
中性子星の観測と理論＠京大

Which physicalparameters areneeded to conclude?
31. Why Magnetar Astrometry?

Missing Link: Magnetar and SNR
http://www.physics.usyd.edu.au/~bmg/fig_sgr_snr.gif

SNR HB9 (τsedov~6600 yr)(G160.9+2.6)

MSP1811-1925
TMSP < 8000?

δR.A.=100s ≒1200 years
δDec=1130” ≒7500 years
Inconsistent each other

TSNR ≒1633 years(China astrologers)
D ≒ 5kpc (HI)4800′′ >>0.32′′ x 104
0501+4516 (τc~10,000yr)

Chandra upper limit of 0.32”/yr
may reject this progenitor (Mong& Ng 18, assuming D=5kpc)
2019/9/3

TXTE ≒10000 years (P-Pdot diagram)D ≒ 3.3kpc (DM)
Credit: ROSAT/XMM/M. Roberts

VLBA astrometry of v= 212 km/s
toward SW may reject thisprogenitor (Helfand+07)

SKA-Japanシンポジウム2019

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2. Observation and Analysis

Magnetar Observation Team of VERAn MOT VERA: Developing our VLBI experience ofobserving neutron stars (and FRBs) toward the SKA

Dr. Akahori (NAOJ)
VLBI

Ms. Eie(NAOJ)
Pulse

Dr. Hirota(NAOJ) VLBIDr. Oyama(NAOJ)
MonitorProf. Terasawa(NAOJ) Pulse

Dr. Kisaka(Aoyama) theory
2019/2/20

Dr. Aoki(Yamaguchi)
Pulse, JVN

Dr. Enoto(Kyoto) X-ray©academist Journal

More Contributors

Prof. Yonekura(Ibaraki)Prof. Misawa, Dr.
Tsuchiya [Tohoku]
Prof. Honma
Dr. Sekido, Dr. Takefuji(NAOJ) Advisor(NICT)

中性子星の観測と理論＠京大5

2. Observation and Analysis

Observing Strategy with VERA
Why VERA 22 GHz?
1. Resolution = 1.2 mas!
• Can capture 1.7 mas/month for
200 km/s @ 2 kpc

2. Sensitivity = 0.2mJy!
• per 8hr per 128MHz (open use)
• Note: 2048MHz for SWG

Target selection criteria
1. At anti-galactic center tomeet low DM & low timepressure.
2. With phase calibrators

NameP(sec)

D(kpc)

Flux(mJy)

SNR

SGR0501+452

5.76

1-5?

300?

HB9?

4U 0142+61

8.69

3.6?

???

?

• Ideal: d < 2 , S > 300mJy• OK: d < 3 , S > 60mJy

1E 2259+586

6.98

3.2?

???

CTB
109?

nException = outburst (ToO) àXTE1810-197

5.54

3-5?

10?

G11.2-0.3?

2019/2/20

中性子星の観測と理論＠京大6

2. Observation and Analysis

Result of SGR0501 VLBI Imaging
2 538R18093A(2018/4/3)

39 94
1.

3C8400501+443

210hr
76380.99

39 94
1.

3.367 Jy061.69 mJy

rms
0.18mJy/beam

22 538R18148B(2018/5/29, 55days)

39 943C84

1.

0501+4430210hr
7638

39 94
1.
03.083 Jy

74.11 mJy

rms
0.51 mJy/beam

2

2019/2/20

中性子星の観測と理論＠京大7

2. Observation and Analysis

Result of SGR0501 VLBI Imaging
0.3 Jy (expected)↑Data taken by Oyama (monitor)
Bandwidth = 2048 MHz↑Data taken by Akahori (deep)
Bandwidth = 128 MHz
2018• No radio emission was detected• An upper limit of 0.2-0.5 mJy à top 20% of known
normal radio pulsars are excluded
2019/2/20

中性子星の観測と理論＠京大8

2. Observation and Analysis

Revival of XTE1810 Radio Outburst

18.12.18
19.01.07
19.01.21
19.02.15

Iitate 31m (0.3 GHz), Kashima 34-m (2 GHz),
Hitachi 32-m (7/8 GHz), four VERA 20m (22 GHz),
and NICER and Swift18.12.14
18.12.18
18.12.18
19.01.07
19.01.07
19.02.15
19.01.21
19.04.23
19.02.15
19.06.12

VERA
18.12.18
19.01.07
19.01.21
19.02.15

2019/9/3

18.12.18
19.01.07
19.01.21
19.02.15
SKA-Japanシンポジウム2019

18.12.13
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18.12.14
19.04.23
19.01.07 19.06.12
19.02.15
19.03.04
19.04.23
19.06.12JVN

92. Observation and Analysis

Result of XTE1810 VLBI Imaging
R18352A(2018/12/18)
1.32

B1730-130
1.6764 Jy
4.056E-02 JY/BEAM

J1808-1822
24.638 mJy
6.350E-04 JY/BEAM

XTEJ1810?
26.993 mJy?
4.275E-04 JY/BEAM

nNo radio emission was detected
nData taken in January 7 would be more promising

2019/9/3

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3. Future Prospect

K-band VLBI of Magnetars (ToO)
8kpc=0.45mas

2kpc=1.7mas

4kpc=0.85masnResolving the propermotion of 200 km/s
in a month

MOT-VERA
Magnetar Observation Teamof VERA
Local arm, Perseus arm
VERA 3000 km = 1.2 mas

MUAY-THAIMUAY-THAI (2023-)

KAIRAKUEM
KAIRAKUEN (2030-)

Magnetar Unprecedented Astrometry
Yielded by Thailand
MOT-VERA + inter-arm, halo
Super EAVN 6000km = 0.6 mas

Key Alliance of International Radio Astrometryat K-band for Ultimate Exploration of NSs
MUAY-THAI + arms + galactic center
SKA-VLBI with EAVN 12000 km = 0.3 mas
https://photolibrary.jp

https://efight.jp/topics-20140411_29954
2019/2/20

中性子星の観測と理論＠京大

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3. Future Prospect

Neutron stars will be your interests=sD2

D=2kpcK-band!
VERA
18A130VERA
12GbpsSuper-EAVN
Case4
SKA VLBI
Band 5cnPersistent radio pulses enable us to perform astrometrynNo detection gives some clues for the emission mechanism
2019/9/3SKA-Japanシンポジウム2019

12SummarynMagnetars Radio Outburst• There is so far no solid identification of progenitor SNRs of magnetars• The trigger of radio outburst is fully unknown

nMOT VERA Project• Four magnetars have been observed• SGR0501: no detection, XTE1810: no, work in progress• We have established the procedures of magnetar VLBI observation
and analysis through our activity in the last 2 years• We are waiting for magnetar radio bursts

nFuture Prospects• MOT-VERA à MUAY-THAI à KAIRAKUEN!
ü Key Alliance of International Radio Astrometry at K-band for Ultimate Exploration of NSs• Is the origin of FRB (e.g., 121102) a young magnetar’s giant pulse?
2019/9/3

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