Ryosuke fukuoka katsuji koyama syukyo g ryu takeshi go tsuru kyoto univ
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Ryosuke Fukuoka , Katsuji Koyama Syukyo G. Ryu, Takeshi Go Tsuru(Kyoto Univ.) PowerPoint PPT Presentation


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2010/10/23. Suzaku discovery of two peculiar clumps at the south end of the Radio Arc (PASJ No.61, Vol.3). Ryosuke Fukuoka , Katsuji Koyama Syukyo G. Ryu, Takeshi Go Tsuru(Kyoto Univ.). Suzaku. JAXA. Outline. ~2′. We successfully detected two peculiar clumps. ~1.′2. Clump B. ~2.5′.

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Ryosuke Fukuoka , Katsuji Koyama Syukyo G. Ryu, Takeshi Go Tsuru(Kyoto Univ.)

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2010/10/23

Suzaku discovery of

two peculiar clumps

at the south end of the Radio Arc

(PASJ No.61, Vol.3)

Ryosuke Fukuoka, Katsuji Koyama

Syukyo G. Ryu,Takeshi Go Tsuru(Kyoto Univ.)

Suzaku

JAXA


Outline

~2′

  • We successfully detected two peculiar clumps.

~1.′2

Clump B

~2.5′

4.0-6.0 keVband image

Clump A

FeIline band image

  • Has strong neutral lines.

  • CaI line is especially strong.

  • Located just at

  • the south end of Radio Arc.


6.4 keV emission from GC

Sgr C

~100pc

LMXB

Sgr A East

Sgr B2

M0.11-0.11

Sgr B1

6.4 keV(FeI line) GC map

New clump

M0.74-0.09

  • 6.4 keV clump

  • These structures are an unique feature of high energy activety in GC

  • Positionally correlated with Molecular Clouds (MCs)

  • The origin is actively debated :

  • irradiation by X-rays from Sagittarius (Sgr) A* (Koyama+ 96)

  • OR

  • impact of electrons (Yusef-Zadeh+ 07).


FeⅠ

How to emit neutral lines

  • Neutral emission lines are due to …

Irradiation by X-rays

Impact of electrons

OR

ionization

K-shell

ionization

Photo Abs.

ionization

FeⅠ

e-

X-ray

Continuum:Bremsstrahuling

Continuum:Thomson Scat.

Different processes make the spectra different,

in peculiar the equivalent widths (EWs) are different.

e.g. EWs of 6.4 keV line are : ~1000 eV (X-ray : Murakami+00)

and ~290 eV (electron : Tatischeff 03)


Non-thermal radio filaments

~100pc

Sgr B1

Sgr A

Radio Arc

Sgr C

Sgr B2

Aim here

90 cm GC map (LaRosa+00)

  • Radio Arc (e.g. Yusef-Zadeh+ 84)

  • Largest-scale non-thermal filament

  • Have a strong magnetic field

  • Relativistic electrons would be abundant

 X-ray emission from electrons should be found near Radio Arc.


Discovery of two clumps

~2′

~2.5′

PSF+Const.

PSF+Const.

~1.′2

χ2/d.o.f. = 36.4/10

G 0.162-0.217

χ2/d.o.f. = 16.9 / 6

G 0.174-0.233

Radial profile of G 0.174-0.233

Radial profile of G 0.162-0.217

6.4 keV line band image

4.0-6.0 keVband image

  • Detection of G0.174-0.233 (Clump A)

  • Detection of G 0.162-0.217

  • (Clump B)

the both are diffuse sources


Spectrum of Clump A

0.01

Ar

Fe

Ca

10-3

Intensity (Cts /s /keV)

2

0

χ

-2

2

Energy(keV)

5

10

Results of fit

Spectrum and model

  • Has strong neutral iron (6.4 keV) line.

  • Detected CaI line with ~3σ,

  • and found a sign of ArI line (with ~1σ).


Spectrum of Clump B

0.01

Fe

10-3

Intensity (Cts /s /keV)

2

0

Results of fit

χ

-2

2

Energy(keV)

5

10

Spectrum and model

  • Has weaker line and steeper continuum (than Clump A),

  • although the absorbing column is almost the same.


The origin of Clump A

Only the X-ray origin consistent with the observation.

The X-ray origin is closer to the observation.

X-ray origin is more favored.

Clump A would be a MC irradiated by X-rays

(Solar Abundance ref. Anders & Grevesse 89)


Where is the irradiating Source?

obs. NH

~7.5 × 1022 cm-2

typical NH for GC

~6 × 1022 cm-2

NH of MC

=

+

~ 1022 cm-2

The column density of the cloud would be ~ 1022 H cm-2.

  • If Sgr A* was the illuminating source…

The past outbursts (300 years before)

should have been lasting until 150 years ago.


The origin of Clump B

  • The observed NH (~5.5×1022 cm-2) is typical for GC.

  •  Clump B would be at GC

  • We estimated contamination of 6.4 keV line from Clump A.

  •  The rest EW of FeI is ~ 200 eV.

The value is consistent with the electron origin (~290 eV).

4.735GHz radio

  • Clump B is located

  • just at the south end of Radio Arc.

  • There would be large quantities of

  • electrons along the magnetic field.

Clump B

The origin of Clump B

may be an impact of electrons.

NRAO/VLA

Clump A


Summary

  • We conducted deep Suzaku observation at the

  • south end of Radio Arc, and found two small clumps .

  • EWs of Fe and Ca line support that Clump A

  • comes from irradiation by X-rays.

  • Outburst of Sgr A* would have been lasting

  • until 150 yeas ago.

  • Clump B maybe come from impact of electrons because

  • of the location (the south end of Radio Arc) and the EWFe

Thank you!


Thank You!


Required B for Clump B

Lx(0.1-100 keV) / (dW/dt) > 4.2e-5(Tatischeff 03)

Lx (0.2-16 keV) ~ 1.6e+34 (erg/s)

  • Required number of electrons >~1 ×10-3 [e-/cc]

  • Required magnetic field >~ 70 [μG]

Typical magnetic field for GC ~ 100 [μG]

Magnetic field of Radio Arc ~ 1 [mG]


ContamiFit (Clump B)

EW⇒82―268eV


Suzaku XIS

Suzaku has CCD camera systems :

X-Ray Telescope &

X-ray Imaging Spectrometer (XIS)

  • Capable of Imaging and Spectroscopy

  • Half-power diameter ~ 2’

  • Energy range : 0.3-12 keV

  • High-energy resolution (~150 eV @ 5.9 keV)

  • High sensitivity (low / stable background)

    Suzaku is good at studying dim / diffuse sources.

XIS on Suzaku


SNRscenario

Fe

Fit with NEI model (Z = 1 solar)

  • Cannot explain the Ca line.

  • Needs too high temparature for SNR.

  • (needs a few 10 keV)

⇒set the Z of Fe,Ca free...

non-thermal component?

Zca is too high

⇒+Pow. model also X


ContamiFit

EW⇒82―268eV


12CO(J=1-0) Image

(Oka et al. 1998)

l=0°

b=0°

Sgr A*

-220~+220km s -1


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