ASTRO-H Studies of Accretion Flow
onto Supermassive Black Hole2015 October 21
The Institute of Physical and Chemical Research (RIKEN)
Nishina center

Hirofumi Noda
AGN meeting @ Rikkyo Univ.

1. Contents
I. Introduction
II. Geometry and State of Accretion Flow in NGC 3516
è With X-ray and Optical Correlation
III. Phase Change of Accretion Flow in NGC 3227
è With Drastic Change of X-ray Variability
IV. ASTRO-H Studies of Accretion in Seyferts

AGN meeting @ Rikkyo Univ.

I. Introduction

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1. Accretion Flow onto Black HoleCyg X-1 X-ray spectrum	
High/So5	
Low/Hard	

1	
Disk	0.1	

Corona	Compton	

Hard tail	
Disk black body	High/So5	L/LE	  =	  η	0.01	

BH	Black	  body	

Low/Hard	☆ In black hole (BH) binaries, disk black body appears in X-ray bandè Inner disk temp. with MBH ~ 10M⦿ is consistent with b.body temp. of ~1 keV☆ Broad-band continuum with high energy cutoﬀ at several hundreds keVè Comptonization to disk b.body (Inhomogeneous corona, Maxima+08)☆ With higher η , disk b.body becomes dominant, changing accretion state
BHB spectra are explained with truncated disk and broad corona
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1. Accretion Flow onto Black HoleCyg X-1 X-ray spectrum	
High/So5	
Low/Hard	Compton	

High/So5	L/LE	  =	  η	
1	Disk	0.1	Corona	Compton	

Disk black body	

0.01	

BH	Black	  body	

Low/Hard	☆ In black hole (BH) binaries, disk black body appears in X-ray bandè Inner disk temp. with MBH ~ 10M⦿ is consistent with b.body temp. of ~1 keV☆ Broad-band continuum with high energy cutoﬀ at several hundreds keVè Comptonization to disk b.body (Inhomogeneous corona, Maxima+08)☆ With higher η , disk b.body becomes dominant, changing accretion state
BHB spectra are explained with truncated disk and broad corona
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2. Assumed Accretion Flow onto Supermassive BH
νFν	NGC 1365 (Risaliti+13)	
Fabian & Miniutti+05	
Primary Compton	

Corona	Disk	

BH	Rin < 3 Rs	

Relativistically	blurred refection

Red wing	

Hard X-rayhump☆ Seyferts have η ~ 0.001–1, which is a range between L/H and H/S state in BHBs.
☆ Tanaka+95 : Relativistically Broadened Fe line è Max BH spin in MCG-6-30-15☆ With various satellite broad-band spectra, the soft and hard X-ray excesses
have been interpreted as relativistically-blurred reflection (RBR).
☆Red wing cannot be explained without central compact corona (e.g., Wilkins+15)

è Compact corona with the inner disk radius of Rin < 3 Rs
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3. Geometry Assumed in Optical AGN Studies
Cackett+07

NGC 5548
I

Geometry assumed inoptical studies (Uttley+06)

R1R+5Compact	VB±0
Rin~3 Rs	Lag (day)☆ In optical variations, shorter wavelength precedes longer ones in many Sys(cf. Collier+99, Cackett+07, Mchardy+14)☆ The good correlations were found between optical and X-ray in several Sys
è Optical variation is generated by X-ray illumination☆ Disk is always assumed to have Rin ~ 3 Rs with compact X-ray region
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4. Positioning of Our Studies of SMBH Accretion☆ The corona has been regarded compact, and the accretion disk has been
assumed to have Rin < 3 Rs, regardless of η, in optical and X-ray studies.
☆ Accretion onto SMBH in Seyferts is assumed to be in the High/Soft state,
and to have no state transitionè However, no clear evidence…
☆ We need to determine geometry and state of accretion flow in Seyferts
without model assumptions as possible.
è X-ray and optical variabilities should be utilized☆ In this study, we focus two Seyfert galaxies, NGC 3516 and NGC 3227,
with η < 0.01, which corresponds to the Low/Hard state having
truncated disk and broad corona in BHB.
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II. Geometry and State of Accretion Flow in NGC 3516è With X-ray and Optical Correlation

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5. Hints of Geometry: X-ray and Optical Correlation
0.1

X-ray spectrum in 2013−2014

−1

νFν
0.01

NayutaMITSuME

10-3

2

KanatakeV (Photons cmKiso Schmidt−2s−1PirkakeV )Suzaku10-4

2

520 times variation
ΔF ~ 2.5×10-11 erg/s/cm2
η ~ 0.0005–0.01
10Energy (keV)40☆ To study accretion geometry, we performed X-ray−optical simultaneous
monitoring for 1 year
・ Target: low–η Seyfert NGC 3516
・ X-ray obs: Suzaku 50 ks × 7 with various intervals, days, weeks, months
・ B band obs : Japanese 5 telescope Pirka, Kiso, MITSuME, Nayuta, Kanataè Historically faint phase in X-ray and opticalAGN	  meeEng	  @	  Rikkyo	  Univ.	

6. X-ray and Optical Correlation in NGC 3516

B-band flux density(mJy)

2−10 keV flux
(10-11 erg s-1 cm-2)

4

Epoch 1 2 3 4 53

6Interpolate and compare (Zu+11)

72
10-1
2
1.5

Main hard PL~2.5×10-11 erg/s/cm2~0.82×10-11 erg/s/cm21Pirka, Kiso, MITSuME, Nayuta, Kanata

0.5
0-0.5
56300

56400

56500

56600
MJD56700

56800

Lag~1.7 days

☆ Hard primary X-ray is well correlated with B band
☆ JAVELIN and CCF method reveal that X-ray preceded opt. by ~1.7±0.7 days
☆ Opt. flux increase calculated by B-band is explained by X-ray irradiation
3GMBH Ṁ(1 A)LX
X-ray irr. termStandard disk term
F =+cos2
8 meeEng	  R3 @	  Rikkyo	  Univ.	
4 RXAGN	  7. Contradiction b/w Lag and η in H/S state☆ Results in our monitoring of NGC 3516
1. X-ray preceded B band à X-ray irradiation made optical variation
2. B band lag τ against X-ray is ~1.7 days à ~400 RS/c (MBH ~ 2.5 × 107 M◉)
3. X-ray and optical are in very faint phase à η = 5 × 10-4−0.01
4. B-band flux explained by X-ray irr. à Standard disk term can be 0
☆ τ inconsistent with η (Actual τ larger than that expected from η by ~20 times)è High/Soft state (compact corona) is unsuited for NGC 3516 in the faint phaseη~4X-ray	 B-band

B bandτ ~ 1 day	corona	η ~ 0.01

τ ~ 1 hour 	

BH	disk	400 RS	

< 10 RS	AGN	  meeEng	  @	  Rikkyo	  Univ.	

8. Geometries of Corona and Disk
X-ray
X-ray-luminous
regionNoda et al. (2015) in prep

B-band☆ Disk should be truncated to make τ ~1.7
days and η ~ 5×10-4−0.01 consistent・ Hot accretion flow in Low/Hard state

BH

corona1.7 light day(~400RS)・ X-ray bright point ~1.7 ld far from disk
・ Optical flux is not by α-viscosity
but X-ray irr. (※ particularly N3516 )☆ In many Seyferts, optical lag τ is too large to explain their η (e.g., Cackett+07)
・ NGC 4051、3C390.3 …à τ larger than that expected from η by ~2 times
・ Mrk 509、MCG+8-11-11à τ larger than that expected from η by ~3 times
・ NGC 5548 à τ larger than that expected from η by ~5 times

Seyferts generally have broad corona in the Low/Hard state !
AGN	  meeEng	  @	  Rikkyo	  Univ.	

III. Phase Change of Accretion Flow in NGC 3227
è With Drastic Change of X-ray Variability

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10. Hints of Accretion State: X-ray Variability Change
3−10 keV

13-10 keV Count Rate [cnt/s]

Count Rate [cnt/s]

Suzaku 6 observation (each exp. ~50 ksec)
Light curves

Noda et al. 2014, ApJ, 794, 22 Count-Count Plot

1.52−3 keV

0.1

1Clear break

0.50500 1000 1500 2000 2500 3000
Time [ksec]

000.2 0.4 0.6 0.8 1 1.22-3 keV Count Rate [cnt/s]☆ Spectral hardness drastically changes at the count rate of ~0.16 cnt/s in 2−3 keV
Not due to absorption variation è Dominant primary X-ray changes☆ Two types of primary X-ray are present, diﬀerently from the popular assumption
Diﬀerence spectrum (High−Low spectrum) analyses for individual branches
give us spectral shapes of the primary X-ray (Noda+13; 14)
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10. Hints of Accretion State: X-ray Variability Change
3−10 keV

1

3-10 keV Count Rate [cnt/s]

Count Rate [cnt/s]

Suzaku 6 observation (each exp. ~50 ksec)
Light curves

Noda et al. 2014, ApJ, 794, 22 Count-Count Plot

1.5Hours

2−3 keV

0.1

Bright state1Phase change

0.5Weeks
0500 1000 1500 2000 2500 3000
Time [ksec]

00

Faint state
0.2 0.4 0.6 0.8 1 1.22-3 keV Count Rate [cnt/s]☆ Spectral hardness drastically changes at the count rate of ~0.16 cnt/s in 2−3 keV
Not due to absorption variation è Dominant primary X-ray changes☆ Two types of primary X-ray are present, diﬀerently from the popular assumption
Diﬀerence spectrum (High−Low spectrum) analyses for individual branches
give us spectral shapes of the primary X-ray (Noda+13; 14)
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10-2	
νFν	
10-3	10-4	
2	40 2
Energy (keV)5	5HighLow

21.5

10	10.1

Noda et al. 2014, ApJ, 794, 2Brightphase(a)High−Low
in 1st High(b) 5th−Low

0.01
10-3-4Low
10	High2	40
5	3Energy (keV)	
Bright phaseχ(b)5th−6thFaintphase3-10 keV Count Rate [cnt/s]

0.1	keV 2 (Photons cm −2 s−1 keV −1 )11. Discovery of Two Diﬀerent Primary X-ray

10	40	0Phase change-3High
1040 phase
2510
FaintLow
00 0.2 0.4 0.6 0.8 1 1.22-3 keV Count Rate [cnt/s]
0.5

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40 2
Energy (keV)0.1	(b)5th−6thFaintphase

10-2	
νFν	
10-3	HighLow

keV 2 (Photons cm −2 s−1 keV −1 )11. Discovery of Two Diﬀerent Primary X-ray
0.1

Noda et al. 2014, ApJ, 794, 2Brightphase(a)High−Low
in 1st High
Low

0.01

NH≲1022 cm-2
Diﬀerence-3
Hard Primary 10+0.19
NH~1023 cm-2 (Γ=1.84 −0.17)

10-4	
2	5	10	Low η	-41040	 3 2	Energy (keV)	

(b) 5th−5	DiﬀerenceSoft Primary+0.20(Γ=2.41 −0.18)
10	40	High η	χ☆ Accretion onto SMBH causes two distinct0primary X-ray (often simultaneously)
Hard Primary : Flat spectrum (Γ ~ 1.8); strong neutral absorption (NH ~ 1023 cm-2);-3
t.scale is ~ weeks; dominates with low η
51040 251040 240 2
è Compton in the Low/Hard state

Energy (keV)

Energy (keV)Soft Primary : Steep spectrum (Γ ~ 2.4); weak neutral absorption (NH ≲ 1022 cm-2);
t.scale is ~hours; appears with high η, together with Hard Pri.
è Hard tailin the High/Soft state
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0.1	 (b) Faint-Branch result

Faint phase
Hard10-2	 Primary
νFν	
10-3	

Reflection
10-4	40 2
Energy (keV)χ keV 2 (Photons cm −2 s−1 keV −1 )11. Discovery of Two Diﬀerent Primary X-ray
0.1

Noda et al. 2014, ApJ, 794, 2(a)Bright-brach
Brightphaseresult

0.01

Soft Primary
10-3

Reflection-4510Low η	40(b) Fai

102

Energy (keV)	

510High η	40 2
Energy (keV)☆ Accretion onto SMBH causes two distinct primary X-ray (often simultaneously)
Hard Primary : Flat spectrum (Γ ~ 1.8); strong neutral absorption (NH ~ 1023 cm-2);
t.scale is ~ weeks; dominates with low ηè Compton in the Low/Hard stateSoft Primary : Steep spectrum (Γ ~ 2.4); weak neutral absorption (NH ≲ 1022 cm-2);
t.scale is ~hours; appears with high η, together with Hard Pri.
è Hard tailin the High/Soft state
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0.1	 (b) Faint-Branch result

Faint phase
Hard10-2	 Primary
νFν	
10-3	

Reflection
10-4	

40 2
Energy (keV)χ keV 2 (Photons cm −2 s−1 keV −1 )11. Discovery of Two Diﬀerent Primary X-ray
0.1

Noda et al. 2014, ApJ, 794, 2(a)Bright-brach
Brightphaseresult

0.01

10Low η	

40

10Soft Primary

HardPrimary

10-3

Reflection-4

5(b) Fai

2

Energy (keV)	

510High η	

40 2
Energy (keV)☆ Accretion onto SMBH causes two distinct primary X-ray (often simultaneously)
Hard Primary : Flat spectrum (Γ ~ 1.8); strong neutral absorption (NH ~ 1023 cm-2);
t.scale is ~ weeks; dominates with low ηè Compton in the Low/Hard stateSoft Primary : Steep spectrum (Γ ~ 2.4); weak neutral absorption (NH ≲ 1022 cm-2);
t.scale is ~hours; appears with high η, together with Hard Pri.
è Hard tailin the High/Soft state
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12. Interpretation of Phase Change of NGC 3227
NGC 3516,
Faint phase	 NGC 3227 faint	Mixture phase	 NGC 3227 bright	

Hard Primary

BH	

RIAF
(Low/Hard)	
Low η	

Standard
disk	

Hard Primary Soft PrimaryStandard
disk	
BH	 RIAF
Hard tail region(Low/Hard)	 (High/Soft)	
High η	☆ NGC 3227 shows phase change from Faint to Mixture phaseFaint phase à Hard Primary (Low/Hard)
Mixture phase à Hard Primary + Soft Primary (Low/Hard + High/Soft)☆ Many Seyferts like MCG-6-30-15, IC4329A, NGC 4051, … are in the Mixture
state (à Maxima-sensei’s talk at this afternoon)
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IV. ASTRO-H Studies of Accretion in Seyferts

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13. Our Studies of Accretion onto SMBH with ASTRO-H
Hard PrimarySoft Primary Optical
Both illuminate disk?

Hard tail region Standard
BH	
RIAF (Low/Hard)	 (High/Soft)	
disk	
☆ Hard and Soft primary X-ray both can illuminate disk, increasing optical• Correlation between Soft pri. and opt. is good as well as Hard Primary ?
• How large amount of energy is given to disk by X-ray irradiation?

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13. Our Studies of Accretion onto SMBH with ASTRO-H
Can wind contribute the state transition from High/Soft to Low/Hard ?
Hard PrimarySoft Primary Optical

Hard tail region Standard
BH	
RIAF (Low/Hard)	 (High/Soft)	
disk	
☆ Hard and Soft primary X-ray both can illuminate disk, increasing optical• Correlation between Soft pri. and opt. is good as well as Hard Primary ?
• How large amount of energy is given to disk by X-ray irradiation?
☆ In an accretion flow, two diﬀerent states with diﬀerent accretion rate
(Low/Hard and High/Soft states) are present at the same time
• At boundary between the two regions, wind can take away accreting
mass, changing state in a flow?
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14. ASTRO-H Observations of Seyferts
ASTRO-H
0.1

Opt–UVASTRO-H sim.
HXISXS
SGD

Disk0.01

Soft Primary-3

1010

HardPrimaryWindReflection

-4

0.01

0.1

1

10100

☆ Perform sim. observations of ASTRO-H and ground telescopes on Syhaving multiple primary X-ray like MCG-6-30-15, NGC 4051, NGC 3227
1. Broad spec. with HXI/SGD è Precise luminosity of Soft and Hard pri.
2. Fe-K abs. features with SXS è Wind strength
3. Optical variations è Variation of disk luminosity
State transition in an accretion flow
X–opt. correlation and energy deposit to disk by X-ray illumination
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15. Summary• With the simultaneous monitor of X-ray and optical, NGC 3516
was found in the Low/Hard state, with the disk truncated at~400 Rs and a hot accretion flow formed at inner region.
• By analyzing the drastic change of X-ray variability, NGC 3227
was found to show the phase change from the Faint (Low/Hard)
to Mixture (Low/Hard + High/Soft) phase.
• By observing Seyferts with ASTRO-H and ground-based
telescopes, we can establish the geometries and states ofaccretion flows onto supermassive black holes.

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