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 2014/09/10 2 光赤天連シンポジウム 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 2014/09/10 光赤天連シンポジウム 4 2014/09/10 光赤天連シンポジウム 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 Japanese institutes Extension of A02 sub-project of the “Kakenhi” innovative area of “multimessenger observations of GW sources” 2014/09/10 光赤天連シンポジウム 6 Searching for EM counter part is crucial for understanding the nature of GW sources Metzger & Berger 2012 The most promising GW sources NS-NS merger 2014/09/10 光赤天連シンポジウム 7 2014/09/10 光赤天連シンポジウム 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 2014/09/10 光赤天連シンポジウム 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 NAOJ 1 deg2 NIR camera Yamaguchi 32m radio telescope ★ 3.8m telescope (Kyoto Univ. 2015) Subaru @Hawaii ★ ★ ★ IRSF (Nagoya Univ.) @ South Africa 2014/09/10 MOA-II (Nagoya Univ.) 光赤天連シンポジウム @ New Zeeland miniTAO (Tokyo Univ.) @ Chile 10 Detection of EM counterpart of GW transient with wide-field observations Multi-mode observations physics of EM counterpart The nature of 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 deg2 Camera OAO IR WFC Neutrino obs. (A03) Yamaguchi32m NRAO 45m Multi-wavelen. Multi-mode obs. detailed study detailed study identification emission mechanism redshift -> distance emission mechanism IRSF Coop. theory (A05) 2014/09/10 MOA-II 1.5x1.5deg2 Camera miniTAO World-wide obs. Kanata long term monitor Subaru event evolution HinOTORI 50cm 光赤天連シンポジウム Kyoto 3.8m 11 2014/09/10 光赤天連シンポジウム 12 2014/09/10 光赤天連シンポジウム 13 Pipeline software for transient detection for KISS project Image 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 and asteroid catalog. Select rapidly decaying candidates using multiple exposure data and multi-sites observation data. Send the candidate 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 – 100 deg2). 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-field observations). 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). 2014/09/10 光赤天連シンポジウム 15 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 16 FINAL_POSITION (3.32 deg stat. error) 2 0 1 0 1 1 1 2 2 0 0 iPTF possible counterpart 2 2 2 0 0 2 2 2 0 0 12.5 deg 1 SDSS 2014/09/10 1 1 光赤天連シンポジウム GND_POSITION (2.72 deg stat. error) 17 - KWFC 7+9 pointings - g-band - 180 sec exposure # iPTF counterpart could be a ghost... (no X-ray counterpart there by Swift) 2014/09/10 光赤天連シンポジウムKWFC image 18 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 Zeeland and 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 2014/09/10 光赤天連シンポジウム 19
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