"Stellar-Mass, Intermediate-Mass, and Supermassive Black Holes" Kyoto International Community House, Kyoto, Japan October 28 - 31, 2003 - PowerPoint PPT Presentation

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"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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"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.


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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.


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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.


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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


So we must check how small are the black holes l.jpg

So we must check. How small are the black holes?

~5Rs

Takahashi & Mineshige (2003)

See also Takahashi’s poster in this meeting.


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Shadow Size of Black Holes


If you want to look a black hole shadow should be observed because it is the biggest l.jpg

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


Our galactic central black hole is the most convincing black hole candidate l.jpg

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


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  • 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


Our galactic central black hole is not only the most convincing black hole candidate l.jpg

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).


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SgrA*

Periodic Variation with 106day circle,

Corresponding Flares at 230GHz

230GHz

15,22GHz

Zhao et al 2003


Our galactic central bh rapid changes of its intensity are revealed recently l.jpg

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)


Short time flare of ray baganoff et al 01 porquet et al 03 l.jpg

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


Our galactic central bh rapid changes of its intensity are revealed recently14 l.jpg

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)


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# Eckart’s talk

我々の銀河中心BH,SgrA*

Flare at NIR about 30min. Genzel et al. 2003

(Nature today)


Our galactic central bh rapid changes of its intensity are revealed recently16 l.jpg

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)


Short time flare at mm wave miyazaki et al l.jpg

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)


Structural change of sgra 43ghz l.jpg

Structural change of SgrA* (43GHz)

Flux Density(Jy)

Time

15min integration each (3mas*6mas)

Miyoshi et al.

準備中


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Kato,Mineshige & Shibata 03

See Kato’s poster

0115UT-0700UT

3mas=24au@8kpc

or

500Rs(2.6*10^6Msun)


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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


S is not only the most convincing black hole candidate l.jpg

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


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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.


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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)


Shen et al 200 l.jpg

Shen et al. (2004)

VLBA 86 GHz

SgrA*

1mas

This is the result from the highest frequency VLBI.


Sgra should be observed at mm to sub mm vlbi if you want to look black hole l.jpg

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


First can we get the image of the black hole shadow of sgra with 86ghz vlba l.jpg

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.


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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°)


Locates at observations from the southern hemisphere is preferable l.jpg

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.


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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.


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BIMA

2005: High site is

fully operational

Huancayo

OVRO

virtual

Case2.

realistic sub mm Stations

ALMA

SEST

SMA

Photo by Ota Naomi


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VLBA(VLBIArray)

North

  北

South

Case 3.

Inversed VLBA(さかさVLBA)


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  • 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


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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


In order to image the black hole of sgra we must observe with sub mm vlbi l.jpg

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.


But how about sub mm vlbi with small number of stations l.jpg

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*?


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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


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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


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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.


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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.


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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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