サブミリ波 vlbi による 巨大 bh 観測
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サブミリ波 VLBI による 巨大 BH 観測. 国立天文台 本間 希樹. 日本メンバー:小山友明、原哲也、秦和宏、永井洋、武士俣健、 鈴木駿策、川口則之、河野裕介、江澤元、岩下浩幸 川邊良平、小川英夫 他 国際チーム: Shep Doeleman (MIT), Thomas Krichbaum (MPIfR) 他多数. Fukue et al 1989. Simple question : Is a BH really “black hole” ?. AGN core is most-likely a super-massive black hole. - PowerPoint PPT PresentationTRANSCRIPT
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サブミリ波 VLBI による巨大 BH 観測
国立天文台 本間 希樹
日本メンバー:小山友明、原哲也、秦和宏、永井洋、武士俣健、鈴木駿策、川口則之、河野裕介、江澤元、岩下浩幸川邊良平、小川英夫 他
国際チーム: Shep Doeleman (MIT), Thomas Krichbaum (MPIfR)他多数
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Simple question : Is a BH really “black hole” ?
Fukue et al 1989
•AGN core is most-likely a super-massiveblack hole.
•Yet, there is no confirmation of existenceof event horizon
If one has extremely high resolution and sensitivity,it is expected that BH-accretion disk system constitute ablack hole shadow in a scale of a few R_g.
Direct detection of BH shadow is an ultimate confirmation of existence of BH. (or negative results may indicate an existence of naked singularity !?)
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Apparent size of BHs• Potential targets
Sgr A* M = 4 x 10^6 M_sun, D = 8 kpcθs = 10 μas
M87 M = 3 x 10^9 M_sun, D = 16 Mpcθs = 4 μas
shadow size should be 1 ~ 5 x θs
• Currently-expected resolutionλ= 1mm, B = 8000 kmθ= λ/ B = 25 μas
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Doeleman et al. 2008 in Nature
Key to resolve BH shadow
・ 37±(16,10) Intrinsic diameter of Sgr A* ・ Non detection on the JCMT-CARMA ( 3075 km )
ARO/SMT - CARMA(600km)
ARO/SMT - JCMT
Non-imaging analysis (traditional UV distance plot)
Fukue et al 1989
The most promising way to detect BHshadow : submm VLBI
1) shorter λ, higher resolution 2) less interstellar scattering
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Sub-mm VLBI with ASTEASTE will be a key station for Sgr A* observations
good site & longest baselines
JCMT
CARMA
ASTE
SMTO
UV coverage for Sgr A*( red: UV with ASTE )fringe spacing ~30μas
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To enable VLBI with ASTE• Required components
230GHz RX
Local generator
Down Converter
Recorder
Frequency Standard
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230G-receiver & backends
• Receiver : cartridge-type receiver originally developed for ATF (ALMA Test Facility)
• SpecificationSingle pol.1 x SIS Mixer (DSB) IF output of 4~8 GHz (f ~ 200-250 GHz)
• RX test done on 13-16Oct 2009T_RX ~ 70-80 K (DSB)
RX testingCartridge
Test includes nearly whole system (RX, local, analog backends, sampler)See P-23, P33 for system details
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Frequency standard• H-maser
Kvarz H-maser may be shipped to Chile (Jan/2010),but there are some risks(troubles in transportation,power shut-down problem etc.)
• An alternativeOCXO 8607(the best X’tal)
H-maser
OCXO8607
troposphere
ASD comparison
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Progress at ASTE in Jan 2010
new container (for VLBI instruments)
Cabling through ground
Inside of VLBI container
230 GHz RXinstallation
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Progress at ASTE in Jan 2010 (II)
Backends installedinto VLBI container
Success in signal transfer from RXto VLBI digital backends
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Results – coming soon !?
• First test observations at 230GHz are planedon 1 – 5 in April 2010
stations: ASTE, SMTO, Hawaii (phase-up)
mainly for testing fringes, but some scientific results may be expected !?
• Large international campaign will be conducted in April 2011
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feasibility• ASTE-SMTO/CARMA
D~10 m, B~2 GHzTsys ~ 200, 500 Kτ~ 20 sec
1σ ~ 73 mJy5σ ~ 365 mJy
10m in Chile willconstrain acceretion disk parameters
For Hawaii-Chile, phase-upwill be needed ? Model flux by Fish+ (2009)
1 Jy
2 Jy
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Constraining disk parameters
• RIAF disk with power-low distribution (Yuan+ 93)
• Parameters to fit observations
spin a
inclination θ
PA ξ
amplitude V0
Even three-station results
say something about the
parameters (implying θ>40 deg) Broderick+ (2009)
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Future prospectNear-term
2010 March 230 GHz Single-pol. 4 Gbps2011 March 230 GHz Single-pol. 4/8 Gbps
probably large campaign with other wavelengths2012 March 230/345 ? Single/dual-pol. 8/16 Gbps ?
Mid-termHawaii phase-up on-going (2011?)ALMA phase-up plannedmore telescope LMT?, NZ?, SP?
Target: accretion disk, BH shadow, hot spot motion and GR tests etc, jet launch etc