「銀河系研究会２００６」 ２月２０日（月）〜２２日（水）（会場： 国立天文台 すばる解析棟 大セミナー室）

銀河系中心ブラックホ−ル
SgrA*の降着円盤
Makoto Miyoshi
NAOJ

SｇｒA* is now the mostconvincing super massive
black hole in the universe(Shen et al.05).

The mass 〜４*１０６ Msun
The 1Rs 〜 9.8μas
QPO P=16.8min is
detected at IR and Xray atits short time flaring( IDV).

Motions of Stars around
SgrA*(Genzel et al03)1Detection of IR flaring.
(Genzel et al. 03)

Periodicity was also found from NIR
flaring of SgrA*
P=16.8±2.0 min.(1008±120 sec.）

Genzel et al. 2003

2

QPO at X ray too.

Periodicity is also found from X ray flare. P~100 s, 219 s, 700 s,1150 s, and 2250 s (analysis by Achenbach et al 2004)• At millimeter wave we havealso detected short time flaring(ex. Miyazaki et al.04),
we can expect to detect similarkinds of QPO in radio too!
New detection of SgrA* flaring (IDV)
by Miyazaki in this October using the AT.

• Following the idea we have been checking the data ofSgrA* obtained VLBA since the end of 2001.
• We detected the spatially resolved QPO from theVLBA data taken at 8th March 2004 at 43GHz.
(1.5 days after the millimeter wave short time flare.)3VLBI gives us high spatialresolution( 〜0.1mas）.
So we can investigate thedifferences of QPOｓ between
small regions in the SgrA* image.
First, we check whether the QPOs
are concentrated at the center or
ubiquitous around the whole disk?

(2) 213.3 Rs×121.9 Rs

２(1) 216.3 Rs×423.6 Rs

１３ (3) 106.7 Rs× 60.9 Rs
４ ５(2) 213.3 Rs×121.9 Rs

２６，７，８3mas，305Rs, ２４AU
assumption；DGC=8kpc,MSｇｒA＊ = 4.0×１０６M◎(1) 216.3 Rs×423.6 Rs(2) 213.3 Rs×121.9 Rs(3) 106.7 Rs× 60.9 Rs(4) 71.3 Rs× 40.8 Rs(5) 47.5 Rs× 26.8 Rs(6) 23.8 Rs× 13.4 Rs(7) 15.8 Rs× 9.0 Rs(8) 7.9 Rs × 4.5 Rs

4

Intesity(Jy)(1) 216.3 Rs×423.6 Rs(2) 213.3 Rs×121.9 Rs (3) 106.7 Rs×60.9 Rs (4) 71.3 Rs×40.8 Rs

ふつうのマップ、grid
構造が分解されている（広がり）
ﾚ１）中心列（時系列5min、中心列、ノイズレベル付き）
ﾚ ２）中心列、同・スペクトル、同一Yスケール
構造が左右で異なる
ﾚ１）時系列5min、７・５列、ノイズレベル付き
ﾚ２）７＊５ 同・スペクトル、同一Yスケール
３）中心３つのスペクトル、ピーク比
４）速度強度マップ４）回転を示す、スペクトルの違い
ﾚ５）ぼけた円盤、構造の情報、かなり残っている。
ﾚ６）複屈折現象、
ﾚ７）散乱虫眼鏡（ちょうど３倍強の大きさ）

Noise level(6) 23.8 Rs× 13.4 Rs(1) 216.3 Rs×423.6 Rs(2) 213.3 Rs×121.9 Rs (3) 106.7 Rs×60.9 Rs (4) 71.3 Rs×40.8 Rs

強度→(7) 15.8 Rs× 9.0 Rs(8) 7.9 Rs × 4.5 Rs(5) 47.5 Rs× 26.8 Rs

Ｐ（ｍｉｎ）→(5) 47.5 Rs× 26.8 Rs(6) 23.8 Rs× 13.4 Rs(7) 15.8 Rs× 9.0 Rs(8) 7.9 Rs × 4.5 Rs

QPO spectra become very spiky as the region limited to the center.

5

横0.1mas（10Rs)縦0.15mas（15Rs)のグリッド
３５（＝７×５）grids ａｔ the center

Then we check the spatial distributions of the QPOS.

Time variations of intensity in the grids ( red line; noise level)661-05min

6

2.3

2.6

3.1

3.1

4.5

5.2

6.2

6.6

5.4

6.6

7.8

4.0

5.1

1.9

2.4

2.7

2.6

2.0

5.8

5.2

4.0

8.6

7.7

6.6

5.3

5.8

6.4

5.9

5.0

4.2

2.8

2.92.82.4

2.2

Time variations of intensity in the grids ( The denoted numbers are SNRs)
661-05min

209grids総和

RCL

7

Every grids show something. Here we look carefully at the central 3
grids because those of SNR are higher than 7.

SNR=7.8

8.6

7.7

8

P=17; common all around the disk(?), come from outer edge of disk?
The strongest peak; large difference in periods.
L 0.1mas-east

６２．２
２９．３
１９．４
１７．０
１３１．６
５５．３
３０．２
１７．３
１２．８

center２２４．８
４８．４
２３．８
１７．７１４．３

R 0.1mas-west

QPO Periods
0.1mas west

centerP’/P=０．４７４９２
V=０．６４ｃ
Ｒ＝2.3Rs(if Keplerian)Assumption here P’/P=１

0.1mas west

P’/P= １．７０８２１
V=０．４９ｃ
R=3.3Rs(if Keplerian)
黒線が観測された周期スペクトル、赤は伸縮させたもの

9他にも対応がつくピークがいくつもある

P= 62.15min

P= 131.6min

Intensity Maps of the Periods
P= 62.15min(上）P=131.6min（中）P=224.8min（下）The Peak Position Moves
Towards west as Periods
Become long.

P= 224.8min

Rotation？
1.9mas,(みかけ約１９３R)s10

P=

Intensity Maps of ratherwideband periods

5- 80min(from the top)
P= 5- 80min
P= 80-160min
P= 160-240min
P= 240-320min
The Peak Position Moves
Towards west as Periods
Become long.

P= 80-160min

P= 160-240min

P= 240-320min

It must be due to Rotation!
1.9mas,みかけ約１９３Rs

1700AU

Reid et al.99

8kpc

SgrA*Rotation of the Sun(Galactic Rotation)

15AU
The Accretion Disk of SgrA*
Shows Counter-Rotation
Against the Galactic Rotation.
The Galactic Rotation
Becomes Random
At GC?!

Genzel et al. 03
4*104AU

Genzel et al.03

11There is one thing to be discussed.
“The scale” seems inconsistent.
•From the velocity derived from the shift of spectra
0.1 mas corresponds to 〜3Rs （M=1.2 ×１０７Msun ！）•From the distance (8kpc) and the mass of SgrA*(4×１０６Msun)
0.1 mas corresponds to 〜10Rs>The derived velocity is wrong?
---- Then check the possible theory to sit them well.
Something to change the scale of 0.1mas 10Rs to 3 Rs.

Apparent Radii(Rs) from infinite direction

Self gravitational lensing effect of black holewill play an role of magnifying glass.
2r〜５RsR（遠方からの見かけ）
12•Event horizon (r=1Rs)
seems to be at r=2.5Rs frominfinite direction.
•How about r〜３Rs region?
Magnifying ratio 〜1.23--insufficient to explain the scale
problem--

1086

3.69Rs4

2002683Rs 4Intrinsic Radii(Rs)10

Calculation by Takahashi R.

12

How the Scattering acts asmagnifying glass on SgrA*?

The intrinsic image is
obscured and broadened
because of scattering
effect by circum-nuclear
or inter stellar plasma(∝λ２）.
Shen et al.(05), Bower etal(04) investigated theeffect.
The ratio --２．６〜３＠４３ＧＨＺVLBI images of the SgrA*(Lo etal ’99)

The SｇｒA*の観測上の大きさと本来のサイズの関係
λobs２乗則にのって散乱が効き、大きく見える
From Shen et al.（Nature05）から。
Bower et al (Science 04) –similar result

Intrinsic size 0.28mas
Scattering&Broadening
Magnification Ratio
２．６（４３GHｚ）
＠４３GHｚ0.72mas13

Considering only the mass(400million solar mass) and distance(8kpc):
0.1mas(EW)×0.15mas（NS)＝＞9.7 Rs(E-W)× 16.2Rs(N-S)
magnification ratio：
1)self gravitational lensing effect at r =3Rs
2)scattered&broadening effect by intervening plasma
Total 1.23× 2.6〜3 ＝

1.23
2.6〜3
3.12〜3.7

Considering also the total magnification ratio 3.12〜3.7
0.1mas(EW)×0.15mas（NS)＝＞３.1-2.6 Rs(E-W)× 5.2-4.4Rs(N-S)

These two broadening effects
give us the 〜3Rs resolution!

Does Thompson Scattering
Really Work As
Magnifying Glass on SgrA*?

14

Future prospect×fully obscured
No information on fine structure◎partially obscured
with some information

v=０．４〜０．６ｃrotation

As the accepted theory
says,.SgrA*is obscured bybroadening and scattering below 1
mm wave length.
But there remain some pieces ofinformation of the intrinsic structure!
Because The scattering effect andself gravitational lensing work as
magnifier of SgrA*, we can get the
spatial resolution detection the 3Rs.
VLBI observations of QPO in radio
continuum will give us the chance toinvestigate the line of sight velocity
and the structure of the inneraccretion disk of SgrA*！

Spatial resolution〜３Rs

周期ごとで空間分布が異なる！

SRT+ (X^2Y^2)

Ｘ方向
Y方向

Ｘ方向

Y方向
Y方向

Ｘ方向

15

５６分周期（図：横に引き延ばした）
P＝56minの円盤振動モード
中心、左右の強度変化に注目

構造変化のうち１６．８分周期成分を調べた
ピーク位置（十字）が左右に揺れる。

１６．８分

16

17181920視線速度blue ------------------------------------------------red

この構造変化が円盤の回転と同方向として、この楕円運動が、真上からみて円であるなら、傾きがわかる。
→ほぼedge-onであるが、北側の面を我々のほうに約７度向けている21

Future prospect×fully obscured
No information on fine structure◎partially obscured
with some information

v=０．４〜０．６ｃrotationAs the accepted theory
says,.SgrA*is obscured bybroadening and scattering below 1
mm wave length.
But there remain some pieces ofinformation of the intrinsic structure!
Because The scattering effect andself gravitational lensing work as
magnifier of SgrA*, we can get thespatial resolution detection the 3Rs.
VLBI observations of QPO in radio
continuum will give us the chance toinvestigate the line of sight velocity
and the structure of the inneraccretion disk of SgrA*！

Spatial resolution〜３Rs22

23

24

double refraction by scattering?
複屈折もある？

25

2.3

2.6

3.1

3.1

4.5

5.2

6.2

6.6

5.4

6.6

7.8

4.0

5.1

1.9

2.4

2.7

2.6

2.0

5.8

5.2

4.0

8.6

7.7

6.6

5.3

5.8

6.4

5.9

5.0

4.2

2.8

2.9

2.8

2.4

2.2

SNR & QPO spectra: The double refraction in plasma ?
There exist plausible spectra on the quite low SNR data set(SNR<3)26