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′.

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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

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

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

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).


How to emit neutral lines

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

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

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

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

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

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)


Ryosuke fukuoka katsuji koyama syukyo g ryu takeshi go tsuru kyoto univ

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 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

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!


Ryosuke fukuoka katsuji koyama syukyo g ryu takeshi go tsuru kyoto univ

Thank You!


Required b for clump b

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]


Contami fit clump b

ContamiFit (Clump B)

EW⇒82―268eV


Suzaku xis

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


Snr scenario

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


Contami fit

ContamiFit

EW⇒82―268eV


Ryosuke fukuoka katsuji koyama syukyo g ryu takeshi go tsuru kyoto univ

12CO(J=1-0) Image

(Oka et al. 1998)

l=0°

b=0°

Sgr A*

-220~+220km s -1


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