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Direct imaging of a super massive black hole, SgrA* M.Miyoshi, Pepe Ishitsuka, S. Kameno (NAOJ),

"Stellar-Mass, Intermediate-Mass, and Supermassive Black Holes" Kyoto International Community House, Kyoto, Japan October 28 - 31, 2003. Direct imaging of a super massive black hole, SgrA* M.Miyoshi, Pepe Ishitsuka, S. Kameno (NAOJ), Z. Shen (Shanghai Astronomical Obs.) ＆ S. Horiuchi (SKA)

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Direct imaging of a super massive black hole, SgrA* M.Miyoshi, Pepe Ishitsuka, S. Kameno (NAOJ),

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  1. "Stellar-Mass, Intermediate-Mass, and Supermassive Black Holes"Kyoto International Community House, Kyoto, JapanOctober 28 - 31, 2003 Direct imaging of a super massive black hole, SgrA* M.Miyoshi, Pepe Ishitsuka, S. Kameno (NAOJ), Z. Shen (Shanghai Astronomical Obs.) ＆ S. Horiuchi (SKA) Imaging the vicinity of black hole is one of the ultimate goals of VLBI astronomy. SgrA*, the closest super massive black hole, located at our Galactic center is the leading candidate for such observations. Because of the apparent Schwarzschild radius is estimated to be larger than 6- micro arc seconds from the mass (2.6-3.7*10^6 solar mass) and the distance (8 kpc), the corresponding shadow of black hole is 30 micro arc seconds in diameter and because mm and sub-mm VLBI will soon obtain the sufficient spatial resolutions for the imaging. Recent detections of the rapid flaring from a few hours to 30 min at mm-wave, infrared, and x-ray emissions mean that the structure of the black hole system of SgrA* will also change rapidly. One of VLBA observations at 43GHz really shows such rapid changes of structure of SgrA* occur. We also show performance of a supposing but realistic ground-based mm and sub-mm VLBI array for imaging the SgrA* black hole system.

  2. A simulation of the appearance of black hole with accretion disk (Fukue et al 1989). Light from the other side is bended by the black hole gravity, and then we can see opposite side. At the center ‘black hole ‘ can be seen from where no light come towards us.http://quasar.cc.osaka-kyoiku.ac.jp/~fukue/ See also Fukue’s poster in this meeting.

  3. Radio Interferometer has been trying to resolve the central part of the monsters. Above all, VLBIs have the best instruments for investigating fine structures of the sources.

  4. The nucleus of M87 (VLA,VLBA）This is one of the highest resolution VLBI maps. But, the true face of central massive black hole cannot be seen. As you already saw at Hirabayashi’s talk

  5. So we must check. How small are the black holes? ～５Rs Takahashi & Mineshige (2003) See also Takahashi’s poster in this meeting.

  6. Shadow Size of Black Holes

  7. If you want to look a black hole (shadow),ＳｇｒＡ＊ should be observedbecause it is the biggest.

  8. Our galactic central black holeＳｇｒＡ＊is the most convincing black hole candidate.

  9. SgrA* is now the best convincing MBH. • M=3.65±0.25×106 M. • Eisenhauer et al. 2003 # Eckart’s talk NGC4258 is the second one. Herrnstein et al 1999 Miyoshi et al 1995

  10. Our galactic central black holeＳｇｒＡ＊is not only the most convincing black hole candidate, but now also shows some activities though not so spectacular as its’ old days (# Koyama’s talk).

  11. ＳｇｒＡ＊ Periodic Variation with 106day circle, Corresponding Flares at 230GHz ２３０ＧＨｚ １５，２２ＧＨｚ Zhao et al 2003

  12. Our Galactic central BH，ＳｇｒＡ＊Rapid changes of its intensity are revealed recently. • X ray flare (Td=10^4 –3×10^3sec) (Baganoff et al. 2001, Porquet et al. 2003) • IR flare up for about 30 min (Genzel et al. 2003) • Radio flare upat mm-wave length (Miyazaki, Tsutsumi & Tsuboi 準備中)

  13. 我々の銀河中心ＢＨ，ＳｇｒＡ＊Short Time Flare of Ｘray (Baganoff et al 01, Porquet et al 03) Duration ~ Td=10^4 – 3*10^3 sec Time Baganoff et al 01

  14. Our Galactic central BH，ＳｇｒＡ＊Rapid changes of its intensity are revealed recently. • X ray flare (Td=10^4 –3×10^3sec) (Baganoff et al. 2001, Porquet et al. 2003) • IR flare up for about 30 min (Genzel et al. 2003) • Radio flare upat mm-wave length (Miyazaki, Tsutsumi & Tsuboi 準備中)

  15. # Eckart’s talk 我々の銀河中心ＢＨ，ＳｇｒＡ＊ Flare at NIR about 30min. Genzel et al. 2003 (Nature today）

  16. Our Galactic central BH，ＳｇｒＡ＊Rapid changes of its intensity are revealed recently. • X ray flare (Td=10^4 –3×10^3sec) (Baganoff et al. 2001, Porquet et al. 2003) • IR flare up for about 30 min (Genzel et al. 2003) • Radio flare upat mm-wave length (Miyazaki, Tsutsumi & Tsuboi 準備中)

  17. 我々の銀河中心ＢＨ，ＳｇｒＡ＊Short Time Flareat mm-wave (Miyazaki et al.準備中 ) Td=2*10^3 sec Next day With Nobeyama mm array (NMA)

  18. Structural change of SgrA* (43GHz) Flux Density(Jy) Time 15min integration each （3mas*6mas） Ｍｉｙｏｓｈｉ ｅｔ ａｌ． 準備中

  19. Kato,Mineshige & Shibata 03 See Kato’s poster 0115UT-0700UT 3mas=24au@8kpc or 500Rs(2.6*10^6Msun)

  20. I must do two things before publication of the results. 2) Simplification and Generalization of the reduction procedure from which the images derived. The procedure will be useful for mm-VLBI where atmospheric fluctuations often damage the data. 1)Tests of performance of the snap shot observation mode with VLBA ← An example of testing performance

  21. SｇｒＡ＊is not only the most convincing black hole candidate, but now also shows some activities, has become interestingHowever one nuisance remains. Scattering by surrounding plasma

  22. VLBI images of the SgrA* from 5GHz to 43GHz. from Ｌｏ　ｅｔ　ａｌ　（１９９９） The intrinsic image is blurred and broadened because of scattering effect.

  23. Apparent Size of SgrA* Free from Scattering Effects by Plasma （∝λ＾２） At mm-, sub-mm wave length ! So we can expect observe the intrinsic image at mm-, sub-mm wave length. Ｄｏｌｌｍａｎｎ　ｅｔ　ａｌ．　（２００１）

  24. Shen et al. (200４) VLBA 86 GHｚ SgrA* １ｍａｓ This is the result from the highest frequency VLBI.

  25. SgrA* should be observed at mm to sub-mm VLBIif you want to look black hole.

  26. First,Can we get the image of the black hole shadow of SgrA* with 86GHz VLBA? note. VLBA 86GHz observations of SgrA* is really important to measure the intrinsic size. See deeply the Poster of Shen et al. at this meeting.

  27. VLBA VLBA+ Huancayo+ALMA+SEST 　　さかさＶＬＢＡ at south Here in order to estimate the performance of spatial resolutions of several arrays, ignoring scattering effects and weather conditions, but using the real sensitivities, we made clean simulations. At 86GHz ground based VLBI, the shadow of SgrA* will not be detected only because insufficient spatial resolutions. Image Model Observed typical image + Black Hole Shadow (30×24μasPA=80°）

  28. Then,What kind of sub-mm VLBI arrayshould we construct for imaging the black hole shadow of SgrA*?I made simulations with three types of arrays. ＳｇｒＡ＊ locates at δ＝－３０°, Observations from the southern hemisphere is preferable.

  29. Case 1. VLBA ２５ｍ鏡１０台 最大８０００km基線 （最小フリンジ間隔 ０．２mas＠４３ＧＨｚ） ３００ＭＨｚ～86ＧＨｚ NOTE. VLBA antennas do not have sufficient surface accuracy to receive sub mm radio waves.

  30. BIMA 2005: High site is fully operational Huancayo OVRO virtual Case2. realistic sub mm Stations ALMA SEST SMA Photo by Ota Naomi

  31. ＶＬＢＡ（VLBIArray） Ｎｏｒｔｈ 　　北 南 Ｓｏｕｔｈ Case 3. Ｉｎｖｅｒｓｅｄ　ＶＬＢＡ（さかさＶＬＢＡ）

  32. uv coverage for SgrA* １．５　mas＠８６Ｇ0.56mas@230GHz • dirty beam for SgrA* 1.VLBA 2.SMA+CARMA+Huancayo+ALMA+SEST3. さかさＶＬＢＡ

  33. 230GHz simulations Outer size 0.1mas from Krichbaum obs 1.VLBA 2.SMA+CARMA+Huancayo+ALMA+SEST3. さかさＶＬＢＡ 250μas Super resolution(20μas beam) 使用 Gaussian 0.1×0.08mas, PA=80°,f=3Jy Black Hole Shadow30×24μasPA=80° Good image was obtained from ‘inversed VLBA’ as expected

  34. In order to image the black hole of SgrA*, we must observe with sub-mm VLBI. Image from simulation model We need the same scale array like VLBA, (8000km,10 Stations, same sensitivity as that of 86GHz of real VLBA) located at the southern hemisphere.

  35. But, How about sub-mm VLBI with small number of stations? Image from simulation model Is it useless for investigating the black hole shadow of SgrA*?

  36. An Example of the relation of Visibility Amplitudes and Structure of SｇｒＡ＊ （２３０ＧＨｚ） ＢＨ　 ３．７×１０＾６Ｍｓ Ds=４４μａｓ ＢＨ　２．６×１０＾６ＭｓDs=３０μａｓ NO Black hole NO Shadow Null point shifts with the size of BH shadow, namely BH mass We can estimate the shadow size and then the BH mass with submm VLBI including only small number of stations.b

  37. South America Old 32m communication antenna Construction begins Huancayo 1520km ＡＬＭＡ（日米欧） Virtual now 1960km 800km Since 1987 ＳＥＳＴ１５ｍ鏡（ＥＳＯ） Photo by Ota Naomi

  38. In order to image Black Hole directly: 1)the first and best target should be SgrA* SgrA* has the biggest apparent size of black hole shadow (D=30-45 micro arc sec ) SgrA* shows short time flares, then we can expect to investigate the active phenomena occurring on accretion disk. 2) Sub mm VLBI (230GHz or higher frequency) with like VLBA location (=10 stations & 8000km ) in southern hemisphere is needed to image clearly.

  39. However, from visibility analysis with image models we can begin to investigate BH shadow even with sub-mm VLBI using only small number of stations.

  40. Conclusions So We Should Start sub-mm VLBI at the Southern Hemisphere at once! Thanks ! SgrA* Black Hole Shadow (Falcke et al 00)

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