重力波可視光対応天体探査
内海洋輔（広島大学）+ J-GEM collaboration
冨永望 (甲南大学), 朝倉悠一朗, 阿部文雄 (名古屋大学), Paul Tristram (Mt. John天文台), 諸隈智貴, 土居守, 本原顕太郎, 田村陽一, 酒向重行, 大澤亮 (東京大学), 藤沢健太 (山口大学), 伊藤亮介, 植村誠, 川端弘治, 吉田道利 (広島大学), 伊藤洋一 (兵庫県立大学), 河合誠之, 斉藤嘉彦, 谷津陽一 (東京工業大学), 田中雅臣, 黒田大介, 柳澤顕史 (国立天文台), 松林和也, 太田耕司 (京都大学), 村田勝寛 (名古屋大学), 永山貴宏 (鹿児島大学)

Observed magnitude

22

重力波源候補：中性子星合体

1m

2324

田中(2016)天文月報

2526
27

赤い@可視-近赤外d = 80 Mpc

8m

051015
Days after the merger

1週間程度で暗くなる

Observed magnitude

8m級望遠鏡での深さ

1mz band
200 Mpc

22234m

248m

252627051015

Days after the merger

Tanaka & Hotokezaka 2013, ApJ, 775, 113

2020
21

10倍

4m2010 days

H band20どのように中性子星合体を選び出すか
たくさんのコンタミ
変光星、超新星、AGN、移動天体・・・
O(100)-O(1000)のコンタミから1つの中性子星合体を選びたい
光度変動、スペクトル情報から高効率な選択方法
2バンドでの撮像: i-zで赤い19Type Ia SN
NS-NS (100Mpc)
BH-NS (200Mpc)

z=0.1

数日で暗くなる(速いタイムスケール)~O(1) deg-2 w/ すばる望遠鏡(TM+2008, Yoshida+submitted)

i band limiting magnitude of the HSC ob-1day

21

i magnitude (AB)

重力波天体は系外銀河に付随定常的に光っている銀河・星が邪魔
画像の引き算系外変動天体数日のタイムスケール

20

1day

22z=0.2

236days
HSC 50seclimit. mag.

z=0.3

6days

24

11daysunobservable
area

25

minor planet

26-10

1i-z

2

3

J-GEM = Japanese collaboration for
Gravitational wave ElectroMagnetic follow-up
LIGO, Virgo, KAGRAからの重力波アラートを受けて突発天体の可視・近赤外、電波でのサーベイを行う
LIGO-Virgo Collaboration (LVC)とのMoU (2014年4月)
PI: 吉田道利氏 (広島大学)
16望遠鏡
多経度
北天 + 南天
広視野観測 + 近傍銀河ターゲット観測 (GWGC, White+2011)
高機動力分光観測
電波130˚

140˚40˚40˚

全地球モニタリングネットワーク
MITSuME
Kiso Schimidt
Yamaguchi

NayutaOAO188cm,OAO91cm,MITSuME,Kyoto−3.8m
KanataJ−GEM observation network
330˚0˚30˚60˚90˚ 120˚ 150˚ 180˚ 210˚ 240˚ 270˚ 300˚ 330˚60˚60˚30˚HinOTORI

30˚130˚140˚30˚30˚Subaru

0˚
−30˚

miniTAO/ASTE

IRSF

0˚
−30˚

MOA−II/B&C61cm−60˚330˚−60˚0˚30˚60˚90˚ 120˚ 150˚ 180˚ 210˚ 240˚ 270˚ 300˚ 330˚field-of-view [deg2]

広視野サーベイ能力 (可視近赤外望遠鏡)
ASAS-SN
100[Palomar/ZTF][Kiso/Tomo-e]
10PTF
Kiso/KWFC

DECam

Subaru/HSC

MOAII

1

VISTA

[WFIRST]

0.10.01

PS1[LSST]

Subaru/SCamFRONTIER

HST/ACS
0.125 0.25 0.5[]は将来の計画

124816telescope aperture [m]32即時通報システムはあるGRB (GWよりも即時性の要求) やそれ以前の変動天体通知ネットワークに相乗りする形
Gamma-ray Coordinates Network/Transient Astronomy Network (GCN/TAN)

VOEvent packet
Prob map on healpix grid

FAR(False Alarm Rate)>1/month

利用するためには守秘義務などを取り決めた MoU を LIGO と結ぶ必要がある

高機動力の例：数十秒での観測を実現
TITLE:NUMBER:GCN CIRCULAR
20039

KanataSUBJECT: GRB 161014A:
optical observation
DATE:
16/10/14 16:56:59 GMT
FROM:Michitoshi Yoshida at HASC,Hiroshima U <yoshidam@hiroshima-u.ac.jp>
（略）
# T0+
MID-UT
T-EXP
R mag.
R err
R limit-------------------------------------------------------

86

12:32:48
30
15.1
0.2
17.0
------------------------------------------------------TITLE:NUMBER:GCN CIRCULAR
20036

MITSuME-Akeno optical observation

SUBJECT: GRB 161014A:
DATE:
16/10/14 13:14:41 GMT
FROM:Yoichi Yatsu at Tokyo Tech.
（略）<yatsu@hp.phys.titech.ac.jp>

T0+[sec]
MID-UT
T-EXP[sec]Rc
Rc_err-------------------------------------------------------

46

12:32:2330~14.520.06------------------------------------------------------T0+ : Elapsed time after the burst
T-EXP: Total Exposure timeskymap (最終版)

GW151226

1400 deg2(90% credible region)

http://www.ligo.org/detections.php

GW150914

600 deg2(90% credible region)

J-GEM follow-up for GW150914
Mon, 14 Sep 2015 18:59:45
GW150914 検出！しかし GCN no5ce は流れなかった
Wed, 16 Sep 2015 14:39:44 (Singer)
GCN circular が E-mail で送信された
Wed, 16 Sep 2015 15:07 (吉田)
観測ターゲットリスト作成，visibility が悪いので IRSF (南ア)/ MOA (NZ)に依頼
Thu, 17 Sep 2015 28:07:34 (諸隈，田中雅臣)
KWFC で観測を開始
Fri, 18 Sep 2015
LIGO O1 はじまる
Sun, 20 Sep 2015 ????? (朝倉ほか)
B&C61cm で観測を開始

Morokuma+2016 Kiso/KWFC(24 deg2)

before sunrise and during the astronomical twilight. Therefore,
we chose the i-band filter to avoid high sky background due tothe Sun as much as possible.
The total probability of the regions observed with KWFC
to include the GW source was initially 1.2% but turned out tobe 0.1% in the final skymap. The observed regions are partly
overlapped with regions covered by Pan-STARRS (PS1; Smarttet al. 2016) and MASTER-NET (Lipunov et al. 2016)1 .
The data reduction procedure basically follows that of thesupernova (SN) survey with KWFC (KISS; Morokuma et al.
2014). The 5σ limiting magnitudes are approximately 19 mag
for the first four images and as shallow as 16.2 mag for thelast image due to the twilight. For each of the fully reduced
images, we applied an image subtraction method (hotpants2 )2 Survey (SDSS) images
with deeper archival Sloan Digital Sky
taken several years ago as references. Then, we extract transient
objects with positive fluxes (2.5 σ , 5 pixel connection) in thesubtracted images with SExtractor (Bertin & Arnouts 1996).

skymap (最終版)

GW151226

1400 deg(90% credible region)

2.2 B&C 61-cm Tripole5 Observations
Tripole5 is an optical camera on the B&C 61cm telescope capable of taking images in 6.2 arcmin × 4.2 arcmin field-of-viewin g -, r-, and i-bands, simultaneously.
The observations are started on 2015 September 20, 6.3 days
after the GW detection. We observed 18 nearby galaxies in thehigh probability region of the southern hemisphere as shownin Figure 1 and Table 3. Two to six 120-sec frames weretaken per galaxy in g -, r-, and i-bands on 2015 September
20, 21, 24, and 26. The observed galaxies are selected from

B&C Tripole5(18 galaxies)

mag. Object catalogs for the Tripole5 images are created using
SExtractor.

GW150914

Fig. 1. Final skymap (LALInference) for the GW150914 localization and theobserved regions with KWFC (left) and Tripole5 (right). The color map isshown in unit of probability per HEALPix (Górski
2 et al. 2005) pixel of Nside =92
2 = 512, corresponding to about 47 arcmin . The KWFC field-of-views areshown in box and the area observed with Tripole5 are shown in dots.

600 deg(90% credible region)

3 Results & Discussion

For the KWFC data, radial profiles and SDSS classifications(star/galaxy separation based on probPSF information available in the SDSS database) of all of the transient objects areused to extract extragalactic transients. Known asteroids arealso checked with MPChecker and removed from the transient
catalog. For the Tripole5 data, the object catalog in the entire
observed field of each target galaxy is first compared with theUSNO-B1.0 catalog. There remain some objects without any
counterparts in the USNO-B1.0 catalog and they are visually

http://www.ligo.org/detections.php

J-GEM follow-up for GW151226
Sat, 26 Dec 2015 12:38:53.648
GW151226 検出！しかしまた GCN no5ce は流れなかった
Sun, 27 Dec 2015 26:39:45 (Leo Singer)
GCN circular が E-mail によって流された
Sun, 27 Dec 2015 27:14:22 (内海)
当番観測者（伊藤，中岡，川端）から依頼されターゲットリストを作成
Sun, 27 Dec 2015 30:45:18 (伊藤，中岡，川端，内海）
Kanata/HOWPol 18銀河の観測と即時解析を実施
Mon, 28 Dec 2015 13:30:23 (吉田)各観測所へ観測ターゲットを割り当て
From 28 Dec 2015
Observa5ons started with Nayuta/MINT, Kanata/HONIR, OAO91cm/OAO-WFC, TITOAO50cm/MITSuME, Kiso/KWFCFrom 29 Dec 2015
Observa5ons started with MOA-II/MOA-Red, IRSF/SIRIUS, OAO188cm/KOOLS-IFU (spec)
Thu, 8 Jan 2016 13:59:03 (吉田，本原，冨永，田中，諸隈，仲田，寺居，Finet, 内海)
HSC 観測開始

239 galaxies(最終版)skymap

GW151226

Fig. 3. The positions of the galaxies observed in the J-GEM follow-up observation of GW151226 (red points).

01400 deg2
(90% credible region) 3985 deg2

http://www.ligo.org/detections.php
Yoshida+submittedFig. 4. The distance distribution of the observed galaxies.

Fig. 1. The observed area of the wide-field survey of the J-GEM follow-up

4skymap (最終版)

GW150914

GW151226

Fig. 3. The positions of the galaxies observed in the J-GEM follow-up observation of GW151226 (red points).

0600 deg2(90% credible region)

1400 deg2(90% credible region) 3
Subaru/HSC
50 deg2
985 deg2

Fig. 2. The enlarged view of the survey area by HSC.

http://www.ligo.org/detections.php
Yoshida+submitted

Fig. 4. The distance distribution of the observed galaxies.

Fig. 1. The observed area of the wide-field survey of the J-GEM follow-up

J-GEM フォローアップの達成深さ

Yoshida+submitted

J-GEM電磁波観測@LIGO O1
GW

GW150914

localization~600
deg2(90%)
area & prob.
~900deg2,~50%
by LV-EMsurvey24deg2,0.1%
by J-GEM
nearby galaxies
18galaxies
by J-GEM

GW151226~1400 deg2
> 1000 deg2, ~90%??
985 deg2, 29%
239 galaxies#(telescope)

210

Subaru/HSC

not available

i~24.6, z~23.8@50 deg2

reference

Morokuma+2016,PASJ, 68, L9

Yoshida+ in prep. (summary)
Utsumi+ in prep. (HSC)GW151226 HSC follow up
検出条件|S/N(pdf)| > 5 sigma
in difference image
elongation > 0.8
0.8 < fwhm < 1.3
19

S/N(1.5” ap) > 5 sigma
in science image

1day

21
i magnitude (AB)residual < 3 sigma(psf subtraction in adifference image)Type Ia SN
NS-NS (100Mpc)
BH-NS (200Mpc)

z=0.1

20

1day

22
z=0.2 6days

23

HSC 50sec
limit. mag.

z=0.3

6days

24

11daysunobservable
area

25

minor planet

26-101

23i-z

Figure 2: The i band limiting magnitude of the HSC observation of GW151226 and kilonova light curves. A filled Figure 3: The color evolution of kilonova (Tanaka+triangle represents median limiting magnitudes of the HSC 2014). The interval of the dots on the lines is 5 days.
observation. The theoretical i band light curves of NS–NS The color range of minor planets is shown as thick armerger (pink lines) and BH–NS merger (blue lines) are taken row at the ottom-left of the plot. 5σ detection limit
from Tanaka+ (2014). Solid, dashed and dotted lines corre- with HSC 1 minute exposure is shown by dashed lines,spond to the event distances of 50 Mpc, 100 Mpc, and 200 and the gray colored area is unobservable region withMpc, respectively.
this project.

detected in 2 epoch

生き残った天体1744

急減光(dm>1.5)186

赤い((i-z)1>1.0 (i-z)2>1.5)

15

instrument in the world which can cover most of the 90% credible area of GW in O2B with 8m telescope detection
capability (see Fig.2). We therefore propose a deep wide-field search of EM counterparts of GW sources with HSC.
We trigger ToO observations to Subaru HSC immediately after (within 6 days) GW alerts, if HSC is銀河に付随するか？

0候補天体例

超新星例

選択条件からは漏れている

J-GEM観測まとめ@O1
J-GEM
北天・南天、多経度にわたる
可視・近赤外、電波での観測グループ
Survey と Targeted モードを併用
GW150914: 24 deg2 + 18銀河
GW151226: 985 deg2 + 391銀河
すばる/HSCが世界で最も効率の良いサーベイ望遠鏡/装置
3回の観測で区別: アラート直後、数日後、1-2ヶ月後急減光して赤い天体を探せば良い
中小口径望遠鏡の機動力を十分に活かせなかった

O2でのJ-GEMの観測戦略

O2開始: 2016年12月? (計6ヶ月間)
O2とO1の違い
GCN Notice が来るはず→機動力が活きる
得られる情報: 距離, 中性子星を含んでいそうかどうか
感度: 検出数の向上 <==> 共同利用時間(ToO)は限られている
8
Publications of the Astronomical Society of Japan, (2014), Vol. 00, No. 0
観測ランの後半はAdvanced Virgoが参加予定(O2b)sible detection of a γ -ray emission associated with GW150914
Virgo参加後はlocalizationも改善
by F ermi satellite (Connaughton et al. 2016), several physical mechanisms for EM emission from a BH–BH merger event「電磁波が出そうな天体」
have been proposed (Morsony et al. 2016; Perna, Lazzti &=Giacomazzo
NS+NS
NS+BHを優先的に2016;orYamazaki,
Asano & Ohira 2016). However,
all of those theoretical works have difficulties in producing
サーベイ観測:すばる/HSC,strong
EM emission by a BH–BHmerger. In addition, questions have been raised for the reality of the γ -ray detection by
木曽シュミット望遠鏡,MOA-II
F ermi both from theoretical side (Lyutikov 2016; Zhang et al.
2016) andobservationaland data analysis side (Greiner et al.
3回:
直後、数日後、1,2ヶ月後
2016; Savchenko et al. 2016; Xiong 2016). Thus there is still
近傍銀河観測:no observational
evidence andそれ以外で分担
concrete theoretical backgroundfor EM emission from BH–BH merger. In other words, the key
ingredient for detection of EM counterpart associated with GW
is whether it contains a neutron star. Hence the information of123

観測装置強化：
チベットロボット三色撮像カメラ HinOTORI プロジェクト
Hiroshima University Operated Tibet Optical Robotic Imager
日中共同のプロジェクト• 50cm RC 望遠鏡 u, Rc, Ic 同時撮像光学系• 視野角 23’x23’• シーイング ~ 0.6”
• 標高5100m — 紫外線透過率が良い• 2013年6月以来3年3ヶ月ぶりに入藏，仮設•

50˚70˚80˚90˚

100˚40˚

30˚

110˚120˚

Beijing
QingdaoNangjing

HinOTORI
Ali
Lhasa

130˚

140˚

150˚50˚40˚Hiroshima

30˚20˚10˚

祝 2016/9/8 First light20˚km

チベット自治区阿里~日本との時差3時間
0 500 1000
70˚80˚90˚100˚110˚120˚130˚

140˚

10˚

150˚

2016/9/9 土星像の取得