Sgr B2

Galactic Center Survey with Chandr

Radio Arc

１ Sgr A East ： Young SNR2 The GC Hot 　 Plasma ： 10keV 3 Sgr B2, Radio Arc ： Molecular Clouds

~2 x 1 degrees

22

Sgr A East & GC Hot Plasma

Scientific Objectives

A) The Dynamics of the Galactic Center

1) Galactic Rotation of the Hot Components vs Cold Matter Center energy of 　 the 6.4 keV line & 6.7 keV resonance line

Q. How different between the Molecular cloud, SNR and Diffuse plasma

2) Direct Observation of Internal motion (Doppler broadening) Radio Arc ~70 km/s, 　 Sgr A East, Expanding Velocity ~1000 km/s 　 Diffuse Plasma 1700 km/s (10 keV)

B) Sensitive Test of the XRNe 　 & Cloud Geometry, Parameters Compton shoulder of the 6.4 keV line from Sgr B2. Compton recoil of the 6.7 keV line (from Sgr A East) of the Radio Arc

C) Diagnostic of the GC plasma

(1) Iron abundances of GC Flux of the 6.4 keV, He-like Ka complex, Kb etc(2) Electron temperature 　 6.7 keV / satellite line complex (Sgr A East)(3) Ionization temperature 　 6.7 keV / Ly alpha (10 keV Plasma)

Sgr B2 and Radio Arc with Sgr B2 and Radio Arc with the 6.4 keV line the 6.4 keV line 　　　　　　　　　　　　　　　　　　　　　　 XRN XRN 　　 Compton Compton 　　Shpulder & Recoil Shpulder & Recoil 　　　　　　　　　 　　　　　　　　　

　　　　　　　　

8

Sgr B2 (100 ksec )Compton Shoulder Peak at 6.37 keV 10 eV (error~10 eV, 10 deg), Forward Compton x Absorption is maximum in front

Line Broadenning Sgr B2 　 70 km /s => ~1.5 eV 　　 Ka 　 center: 6.3825 ～ 0.3 eV　　　 width: 1 .7 eV ～ 0.3 eV Kb 　 center: 7.0404 ～ 0.7 eV　　　 width: 1.3 eV (0-2.2 ） eV 　 (90% confidence)

Radio Arc (100 ksec )Thermal + XRN model 　 6.4 keV line 　　 center: 0.3 eV, width: 0.5 eV 6.7 keV resonance line 　 center: 1.2 eV, width: 1.5 eV

Non-Thermal　X-Ray 　 Filaments

1

2

3

Sgr A*1

2

3

Diffuse Hot Plasma ~10 keV

6.4 keVResonance

Forbidden

Ly α 　 & β

10 keV Hot Plasma 100ks

6.4 keV (6.38--6.42) best error center 6.400 keV 1 eV

width 2.7 eV 2.5 - 3.0

6.701 keV (6.68--6.72) best error Center 6.698 0.5 eV Width 3.2 eV 2.9 - 3.5

6.956 keV + 6.977 keV (6.93--7.00) best error Center1 6.953 1 eV Width1 2.8 eV 1.8 - 3.7 Ceneter2 6.973 1 eV Width2 3.4 eV 3.0 - 3.9

The Galactic Center The Galactic Center regionregion

K. Koyama and A. Senda (Kyoto-U) K. Koyama and A. Senda (Kyoto-U)

Y. Maeda and H. Murakami (ISAS / JAXA)Y. Maeda and H. Murakami (ISAS / JAXA)

The central region of our galaxyThe central region of our galaxy

• Various high energy activities• The nearest MBH (= Sgr A*)• Largely extended hot plasma

– ⇒105 yrs past activity of the GC

• SNR / SNR candidates – ⇒104 yrs past activity of GC

• X-ray reflection nebulae– ⇒103 yrs past activity of GC

Target selectionTarget selection• The GC hot plasma

– plasma dynamics, galactic rotation

• Sgr A East – SNR dynamics, galactic rotation

• Sgr B2 / Radio arc – X-ray reflection nebula, Compton shoulder / recoil

GC hot plasmaGC hot plasma• Neutral Iron (6.4 keV)

– Trace the dynamics of the Cold Molecular cloud

• He/H-like Fe-K (6.7 / 6.9 keV)– Trace the dynamics of the hot plasma

Molecular cloud motion maybe Dominated by Galactic Rotation ⇒　 What regulates the plasma

dynamics ? 　　　　　　　 Galactic Rotation ?　　　　　　　 Thermal motion ?　　　　　　　 Past explosive event of Sgr A* ?⇒　 What is the relation between 　　　　 　 the dynamics of cold and hot

matter ?

Sgr A*

Rotation　curve　near　the　GC　region

Sgr A East

GC hotPlasma

Plasma motionPlasma motion• On the galactic rotation curve

– ⇒　 Vrot 　～　 20 km/s @10 pc – ⇒　 ΔE ～ 0.4 eV

• Thermal motion– ⇒ Vth ～ 170 km/s @10keV　　　⇒ 　 σ ～ 4 eV

• Expanding motion centered at Sgr A*

• XRS 100 ks simulation @6.7 keV resonance line

– ΔE = ±0.5 eV – Δσ= ±0.3 eV Galactic rotation is detectable.

Sgr A EastSgr A East• Chandra confirmed Sgr A

East is an SNR (Maeda et al. 2002).• Mixed-Morphology SNR • High temperature

(2 keV or 1 + 4keV)• High metal abundances (> 3solar)• Regulate the past activity of Sgr A* ?

Key science• Temperature measurement

line ratio 6.9/6.7 • SNR dynamics• Whether on the Galactic rotation curve?

Chandra ACIS-I

Sgr A*

Simulated spectrumSimulated spectrum

• XRS 100 ks simulation• GC hot plasma component is excluded• Si / S / Ar / Fe line• Fine structures around 6.7 keV line can be resolved

• resonance • intercombinations• forbidden• Li/Be-like satellites

• line center error ～　 ±0.3 eV• line width error ～　 ±0.4 eV

6.4-6.8 keV

～ 20 km/s galactic rotation are detectable

Sgr B2 / Radio arcSgr B2 / Radio arc• Giant Morecular clouds

Irradiated by The External source toward the GC.

　　　　　⇒ 　 X-ray reflection nebulae (XRN)

Key Science• Compton shoulder of 6.4 keV

fluorescent　　 　 ⇒　 Prove Geometry of the

Irradiation source• Compton recoil of strong 6.7

keV irradiation ⇒ Prove 3D configuration of

Molecular cloud and Irradiating Source (Sgr A*).

Confirm the XRN model and Trace the past activity of Sgr A*

x1038

(year)

Past　luminosities　of　Sgr　A*

3’

Sgr B2 Sgr B2

XRS 100 ks simulation• Compton shoulder of 6.4 keV is

clearly seen.• 6.4 keV neutral Kα

– Line center ±0.3 eV– Width 1.68 eV(1.32 – 1.95)

• Compton shoulder– Energy uncetainity ～ 10 eV – Intensity ～ 20-30 %

⇒　 Irradiated directionare determined within 10

%

6-7.5 keV

6.37 keV

KαKβ

Absorption edge

Radio arcRadio arc

• Reflection (PL + 6.4 keV fluorescent) +

• Thermal component

6.4 keV molecular cloud ⇒ geometry6.7 keV plasma dynamics⇒

100 ks XRS observation 　

center width 6.4 keV ±0.3 eV ±0.5 eV6.7 keV ±1.2 eV ±1.5 eV 6-7.5 keV

Non-thermal emissionNon-thermal emission

Connection between 10keV--sub MeV bandHigh energy activity at the GC.

Integral IBIS/ISGRI 20-40keV 2deg x 2deg image of GC