吉田道利（広島大学）

2014/09/10

光赤天連シンポジウム1重力波とは何か？
一般相対論によると物体は周りの時間と空間(時空）を歪める。

平坦な時空

その物体が 加速度運動をすると時空の歪みが光速で波として伝わる。
歪んだ時空

これが 重力波である。
まだ直接検出はされていない！
しかし、重力波を放出する天体候補は存在！ 重力波天体観測に 重力波（イメージ）
さらに重力波以外の信号も出す！
よる宇宙物理が可能
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KAGRA計画
VIRGO (仏伊）2014/09/10

GEO(英独）光赤天連シンポジウム3重力波検出の特徴
レーザー干渉計では重力波の振幅 h (無次元)を測定する。
h∝1/d ( dは重力波源までの距離)
感度は距離の逆数に比例

重力波源数∝体積∝ 距離３ ∝感度-3
感度が10倍上がるとイベントは1000倍
現在のLIGOやiKAGRAは連星中性子星合体を100年に1回検出できる。

bKAGRA
KAGR
A

国立天文台内のＴＡＭＡ３００ iKAGRA

2016年を目途に10倍程度感度アップ
すると年間10イベント程度が期待される（KAGRAも同時期同様な感度に到達）
確実に重力波が直接検出される
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5Electro-magnetic follow-up of gravitational
wave transients detected by advanced GW
detectors (LIGO, Virgo and KAGRA) Utilize existing optical, infrared, and radio
astronomical facilities of Japaneseinstitutes
 Extension of A02 sub-project of the“Kakenhi” innovative area of “multimessenger observations of GW sources”


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6Searching for EM
counter part is crucialfor understanding thenature of GW sources

Metzger & Berger 2012

The most promising GWsources  NS-NS merger

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8Michitoshi Yoshida (PI), Hiroshima University
 Kouji Ohta, Kyoto University
 Kentaro Motohara, University of Tokyo Mamoru Doi, University of Tokyo Tomoki Morokuma, University of Tokyo Kenshi Yanagisawa, OAO, NAOJ
 Masaomi Tanaka, NAOJ
 Koji S. Kawabata, Hiroshima University
 Takahiro Nagayama, Kagoshima University
 Fumio Abe, Nagoya University
 Kenta Fujisawa, Yamaguchi University
 Nobuyuki Kawai, Tokyo Institute of Technology

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9Japan Coordinated network for transients observation
A part of the project “Multi-messenger Observations of GW sources”* collaborating with the KAGRA data analysis team* science cases: GRBs, supernovae, blazars, etc.
Main features:
5 deg2 opt. imaging w/ 1m
1 deg2 NIR imaging w/ 1m
opt-NIR spectroscopy w/ 1–8m
opt-NIR polarimetry• 1m Kiso Schmidt telescope
6 deg2 camera  36 deg2•••★
50cm telescope(Hiroshima Univ.
2014)•1.5m Kanata telescope
50cm MITSuME
91cm W-F NIR camera of NAOJ1 deg2 NIR camera
Yamaguchi 32m radio telescope★
3.8m telescope(Kyoto Univ.
2015)

Subaru @Hawaii★
★

★
IRSF (Nagoya Univ.)@ South Africa
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MOA-II (Nagoya Univ.)
光赤天連シンポジウム@ NewZeeland

miniTAO (Tokyo Univ.)@ Chile10

Detection of EM counterpart of GW transientwith wide-field observations
Multi-mode observations physics of EM counterpart

The natureof GW transient

GW alert
LIGO/Virgo/KAGRA

alert

Wide field obs.
EM counterpart

X-γ obs.
(A01)

Rapid identification
alert to other facilities
Coop.

Kiso 6x6 deg2Camera

OAO IR WFC

Neutrino obs.
(A03)

Yamaguchi32m
NRAO 45m

Coop.

theory(A05)
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MOA-II 1.5x1.5deg2
CameraMulti-wavelen.

Multi-mode obs.

detailed study

detailed study

identification
emission mechanism

redshift -> distanceemission mechanism

IRSF

World-wide obs.

KanataminiTAO

long term monitor

Subaruevent evolution
HinOTORI 50cm
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Kyoto 3.8m

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Pipeline
software fortransient
detection for
KISS projectImage subtraction method to detect transient point sources
 reference images: SDSS, 2MASS, Pan-STARRS, etc.
If there is no reference image available, detect
all the point sources in the object image.

Catalog matching and select uncatalogued point sources.
Exclude moving objects using multiple exposure data andasteroid catalog.
Select rapidly decaying candidates using multiple exposure data
and multi-sites observation data.
Send thecandidate
information
to GW
collab.

Check the coincidence between the positions of the candidates
and nearby galaxy locations and high energy satellite alert.
Keep other transient candidates for next day observation. Make
follow-up2014/09/10
observation for candidate
objects at least for 3 nights.
光赤天連シンポジウム
Try to find slowly brightening and decaying objects.

14What we should consider for GW follow-up
1. Large uncertainty of localization (~10 – 100deg2).
2. Quick and reliable selection of EM counterpart from a large number of candidates(various kinds of transients, ex. SNe, CV,AGN, etc., would be detected by wide-fieldobservations).
3. Follow-up of the EM candidates with multiwavelength and multi-mode observations.
4. Continuous follow-up for detecting slowly
changing EM counterpart (ex. macro-novae).
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Test Follow-up Observation for a Fermi
GBM alert w/ Kiso-Schmidt/KWFC✓ Kiso Schmidt telescope (1.05m) + Kiso Wide Field Camera (KWFC; Sako+2012, SPIE)✓ 2.2 x 2.2 deg2 field-of-view, 8 CCDs (2k x 4k)✓ Quick image subtraction system is almost ready by Kiso Supernova Survey (KISS).
✓ Large storage (30TB) for SDSS reference images is being prepared.
✓ GBM416242156: 2014/03/11, 14:49, UT✓ Localization error of Gamma-ray Burst Monitor (GBM) from Fermi satellite is comparable
to that of GW.
✓ GRB is “MOST_LIKELY”✓ GBM localization✓ systematic error: 2-3 deg (Singer+2013)2014/09/10 error: ~3 deg
光赤天連シンポジウム✓ statistical

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FINAL_POSITION (3.32 deg stat. error)

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101

1

12200

iPTF possible
counterpart

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200

2

2200

12.5 deg
1SDSS

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GND_POSITION (2.72 deg stat. error)

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- KWFC 7+9 pointings- g-band- 180 sec exposure# iPTF counterpart
could be a ghost... (noX-ray counterpart thereby Swift)

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光赤天連シンポジウムKWFC image18

We are developing a coordinated network of opticalinfrared-radio observations for follow-up of GW transients,J-GEM.
 The network contains several existing small opticalinfrared telescopes in Japan, South-Africa, New Zeelandand Chile.
 We exchanged MoU with the LIGO/Virgo collaboration for
EM follow-up this April.


2020年代には複数の重力波望遠鏡が立ち上がる NS-NS合体の場合、距離限界は200Mpc
重力波天文学は必然的にマルチメッセンジャー天文学（電磁波多波長＋粒子）
 光赤外の大きな方向性として考えるべき
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