Unveiling the Nature of AGN
Coronae through Sub-mm andX-ray Observations
Yoshiyuki Inoue(JAXA International Top Young Fellow)
Collaborators: Akihiro Doi, Kohta Murase, Greg Madejski,Tomonori Totani, Yasunobu Uchiyama, Yoshihiro Ueda
AGN workshop, Tokyo, 2015-10-21

Contents• Introduction• Cosmic MeV gamma-ray background• Synchrotron radiation from AGN coronae• SummaryRelativistic Iron K line
• Iron line
• a probe for the generalrelativity• Depends on continuum• Careful understanding ofcontinuum is necessary.

Tanaka+’95

What makes AGN X-raycontinuum emission• Power-law continuum isgenerated byComptonization of disk
photons in the disk corona.
• “Corona” is important.
• But, how are theygenerated?
Ricci ’11

Observed properties of disk coronaeCoronaDisk

BHDisk• High energy cutoﬀ➡

92Te ⇠ 10 K (kB Te ⇠ 10 keV)

• Power-law spectrum• Compton-y parameter✓2(y = 4kB Te /⌧e me c ⇠ 1)◆✓◆ 1

k B Te
MBH3cm• ne ⇠ 108100 keV10 M• Assuming the size of a corona as l = 10Rs9

Magnetic ReconnectionHeated Corona ModelLiu, Mineshige, Shibata ‘02

1.Reconnection heating = Compton Cooling in corona
B24kB TeVA ⇡ne T cUseed l ⇠ ycUseed
24⇡me c!

2.Conduction heating = evaporation cooling✓in disk◆
1/2
7/2k B Te
chromosphere k0 T⇡
ne k B T el
1mH!

➡

Te ⇠
ne ⇠

10109✓

9✓◆3/4 ✓

B103 G◆3/2 ✓

B103 Gl◆1/8 ✓

◆ 1/4

Useed
K14
5
3
10 cm
10 erg/cm◆ 3/4 ✓
◆ 1/2lUseed
3cm
1014 cm
105 erg/cm3• Assuming equipartition of magnetic energy with gas energyin the disk.

Cosmic MeV Gamma-rayBackground
YI, Totani & Ueda 2008
YI, Murase, Madejski, & Uchiyama 2013

E2 dN/dE [keV2 cm-2 s-1 keV-1 sr-1]

Cosmic MeV gamma-ray background
ASCAXTEINTEGRALHEA01-A4
COMPTEL
HEA0-I
Swift-BAT
Nagoya-Ballon
SMM
COMPTEL
Fermi-LAT

102

101

• Smooth connection to the

CXB.
• likely to be Seyferts, butthey have cutoﬀs at ~100
keV.
R. Gilli et al.: The synthesis of the cosmic X-ray background90100

10-1100101102

103

104

105

106

107108Photon Energy [keV]
Gilli+’07

Fig. 15. a): The cosmic XRB spectrum and predicted contribution from the population of Compton-thin AGN. The diﬀerent XRB measurements
are explained on the top left: diﬀerent instruments on board HEAO-1 (Gruber 1992; Gruber et al. 1999); ASCA GIS (Kushino et al. 2002); ROSATPossible Origins of the Cosmic MeV Background• Type Ia Supernovae?
(e.g. Clayton+’75, Zdziarski+’96)-> not enough (e.g.
Horiuchi+’09, Lacki+’12).
•Radio Galaxies? (e.g.
Strong+’76)• Seyferts? (e.g. YI+’08)-> magnetic
reconnection
heated corona(Haardt & Maraschi ’91, Liu+’02)?

-> not enough (e.g.
•

Massaro & Ajello ’11, YI’11)• FSRQs? (Ajello+’09)

MeV Dark Matters?

-> two peaks in
MeV and GeV?

(e.g. Olive & Silk ’85)-> no naturalcandidate

Hard X-ray Spectra (Seyfert)
corona
E2dN/dEw/ nonthermal
thermalInput
photonMushotzky+93

Energy (keV)

YI+’08• Comptonization in a hot corona above the disk.
• MeV power-law tail is observed in a Galactic X-ray binary (Cyg X-1).
• If non-thermal electrons exist in a corona, non-thermal tail is

expected (e.g. YI+ ’08).

Seyferts and Cosmic MeV Gamma-ray Background2
2-2 -1-1-1E
2 dN/dE(keV cm s keV
2 sr )

E dN/dE (keV/cm /s/sr)

102(K,atr)=(3.8,4.4)=(3.8,4.0)=(3.8,5.0)=(3.5,4.4)=(4.1,4.4)
thermal model
SMM
HEAO-1COMPTEL• Required non-thermal

electron distribution issimilar to that in solar
flares and Earth’s
magnetotail

w/ nonthermal

101➡Magnetic

reconnection-heatedcorona?

thermal100(Liu, Mineshige, & Shibata ’02)
102

103
Photon Energy(keV)

Energy (keV)104

YI+’08

Typical Spectra (Blazar)
49

FSRQ

Log10 iLi(erg s-1)

Log10 (νLν [erg/s])

48• Two peaks

47• Synchrotron

46• Inverse Compton

45• Luminous blazars tend to44

have lower peak energies

43(Fossati+’98, Kubo+’98)

BL Lac • Flat Spectrum Radio

42
41-5

05Log10 Ea (eV) [eV])
Log10 (Energy10Fossati+’98, Kubo+’98,
YI & Totani ’09

Quasars (FSRQs) are
generally more luminous
than BL Lacs.

E2d-410 as indicated ine CXB and contribution of the FSRQs (blue region). The data points are different measurements of the diffuse background75; Gendreau et al. 1995; Watanabe et al. 1997; Weidenspointner et al. 2000; Revnivtsev et al. 2003; Ajello et al. 2008b). The dashed line iseyfert-like AGNs computed with the model of Gilli et al. (2007) arbitrarily multiplied by 1.1 to fit the CXB emission at 30 keV. The solid
ert-like and FSRQs. The spectrum of FSRQs has been modeled as a power-with a mean photon index of 1.6. The blue region represents therom the Monte Carlo realizations of best-fit parameter ranges. The magenta solid line represents the contribution of BL Lac-5objects whose
10or clarity, but is, due to the low number of objects, >30% at any energy.
10-210-1
ure is available in the online journal.)

Blazars and Cosmic MeV Gamma-ray Background110102310104510

Energy [MeV]RXTE - Revnivtsev et al. 2003
Swift/BAT - Ajello et al. 2008
FSRQs, this work
Gilli et al. 2007

10110-1
110102
Energy [keV]

310104E2dN/dE [MeV cm-2 s-1 sr -1]

102
E2dN/dE [keV cm-2 s-1 sr -1]

10-1

Nagoya balloon - Fukada et al. 1975
ASCA - Gendreau et al. 1995
SMM - Watanabe et al. 1997
COMPTEL - Weidenspointner et al. 2000

Nagoya balloon - Fukada et al. 1975
SMM - Watanabe et al. 1997
COMPTEL - Weidenspointner et al. 2000
EGRET - Strong et al. 2004
Swift/BAT - Ajello et al. 2008
IGRB (Abdo et al. 2010b)
IGRB + Sources (Abdo et al. 2010b)
Contribution of FSRQs10-2

10-3

10-4

10-5

Ajello+’09

10-2

10-1

1102
10
Energy [MeV]

310104

5

10

Ajello+’12

f FSRQs (blue region) to the CXB. The data are the same as in Figure 15, but in this case theSED11.
ofContribution
the FSRQsofhasbeen modeled
Figureunresolved(top) andwith
total (resolved plus unresolved, bottom) FSRQs to the diffuse extragalactic background (blue lineon. The IC peak is located in the ∼MeV region. The contribution of BL Lac objects is the sameas in Figure
15 and isfunction
not drawn
hereto forby integratingthe luminosity
coupledthe SED model derived in Section 5.3. The hatched band around the best-fit prediction shows thpresents the range of values obtained from the Monte Carlo realizations of best-fit parameter ranges.
uncertainty while the gray band represents the systematic uncertainty.
(A color version of this figure is available in the online journal.)
ure is available in the online journal.)• FSRQs explain the GeV gamma-ray background with a peakat ~100 MeV (e.g. YI & Totani ’09, Ajello +’12)

Qs assuming that their IC peak is locatede find that in this case FSRQs account for
ion up to 10 MeV. While there is basicallyspect to the single power-law case below
e of the IC peak makes the contribution ofightly smaller around 1 MeV. We also noteeak beyond 10 MeV produces a negligible
Q integral emission and thus this case is
he single power-law model.
lyses shown here cover well the case ineither located at MeV or at GeV energies

e.g., BL Lac objects and starburst galaxies make significant

where L is the intrinsic (unbeamed) luminosity(double and single power-lawmodel,torespectively).
We mustcontributions
the IGRB intensity.
kinematic Doppler factor
therefore conclude that the contribution of FSRQs to the diffuse!
7. BEAMING:THE
INTRINSIC fraction
LUMINOSITY FUNCTION
emission is relevant and likely
accounts fora substantialδ = (γ − γ 2 − 1 cos θ )−1 ,AND THEPARENT
POPULATION(potentially ∼100%) of the CXB around
1 MeV.
Interpreting
where γ = (1 − β 2 )−1/2 is the Lorentz factor and β
the CXB as a strong constraint,
we deriveLthat
theinpopulation
The luminosities
definedthis work are apparent isotropic
velocity of the emitting plasma. Assuming that theluminosities.
Sincethethe jetmoving at relativistic speedof FSRQ sampled by BAT
must have
ICmaterial
peak islocateda Lorentz factor γ in the γ1 ! γ ! γ2 range then t(γ >1),
Dopplerthe
boosted,luminosities are related
in the MeV band in order
not thetoobserved,
overproduce
diffuse
Doppler factor√is δmin = γ2−1 (when θ = 90◦ ) and thtotheintrinsic
valuesbybackground at ∼10 MeV. Bhattacharya et al. (2009) recentlyis δmax = γ2 + γ22 −1 (when θ = 0◦ ). We adopt a vap
reported for the FSRQs detected by EGRET aLmeanphotonthat applies to the case of jet emission from a rela= δ L,
(21)
index of 2.34 ± 0.15. Since FSRQs have a mean photon index
13of 1.6 in BAT, this implies already that the IC peak is located• FSRQs need another peak at ~1 MeV to explain the MeV

background.

➡Two components in gamma-ray spectra?

Not easy to resolve the MeV sky.

magnetic fields, and relophysical systems, andure of the high energy
ectrometer with an exof measuring the bulk
ence with a resolution
00 km s−1 are desirable.
s is trapped in a gravitas and/or turbulence are
res with their own hotth the dominant cluster.
produced as gas fromto the gravitational pomotions and turbulences
eleration of particles to• via non-thermalnifested
d with sensitive hard X-

Takahashi+’13-112
Figure 1: Diﬀerential sensitivities of diﬀerent
X-ray and γ-ray instru-

Even achievingments
thesensitivity
erg/cm the/s, it is hard tofor an
isolated point source.ofLines10for the Chandra/ACIS-S,
Suzaku/HXD (PIN and GSO), the INTEGRAL/IBIS (from the 2009
resolve the MeV(YI+’15). and the ASTRO-H/HXI,SGD are the 3σIBISsky
Observer’sManual),sensitivity curves for 100 ks exposures. A spectral bin with ∆E/E = 1
mal phenomena in theis assumed for Chandra and ∆E/E = 0.5 for the other instruments.
Note that the XMM-Newton instruments have a slightly better senof modern astrophysics.
sitivity than Chandra for 100 ks, while SWIFT/BAT is characterizedragalactic
cosmic rays• Cosmicbackgroundradiation
is notlimit
isotropic.
by almostthe same sensitivity
as IBIS/ISGRI within the range
f the Universe still refrom 15 keV up to ∼ 300 keV. The sensitivities of the COMPTEL ande will discuss
contribu• Thereis anisotropy
due
to thesky distribution
its origins.
EGRET
instruments
correspondto the all-lifetimeof
all-skysurvey ofCGRO. The curve denoting Fermi-LAT is the pre-launch sensitivity
which are under devel-• Answers are in “Anisotropy”.

Angular Power Spectra of the MeV backgroundClp [(ph/cm2/s)2sr-1]

10-610-7Poisson term only

Flim=1e-10
erg/cm2/s

10-8

10-910-10•

Radio-quiet AGNs (Ueda+’03)
Radio-quiet AGNs (Inoue+’08)
Blazars (Ajello+’09)

Astro-H/SGD
0.1

1Energy [MeV]

10YI+ ‘13b

Astro-H (SGD) / future MeV satellites will distinguish
Seyfert & blazar scenarios through anisotropy in the sky.

Coronal Synchrotron Emission
YI & Doi 2014
Doi, YI, et. al., in prep.

Synchrotron radiation from a corona• If a corona is magnetized, synchrotron radiation isexpected (Wardzinski & Zdziarski ’00, ’01, Laor +’08).
• Synchrotron radiation will tell us about the magnetic

field strength.
• BUT, if it is optically thick, synchrotron self-absorption

eﬀect will suppress the observable flux.

Now we live in the ALMA era.

http://alma.mtk.nao.ac.jp

A Case of IC 4329A
10-12

10-13

iFi [erg/cm2/s]

10-14
10-15

spherical geometry is assumed.
IC 4329A
B=1032 G
B=10 G
3
B=102 G w/ non-th
B=10 G w/ non-th
ALMA (60 sec)

• Coronal properties areconstrained by Suzaku/NuSTAR
joint observation (Brenneman+’14).
• Te = 50 keV, τe=2.34

10-16
10-17

10-18

• Non-thermal population for

the MeV background.

10-19• hard to see the emission from a

10-20
10-21 110pure thermal corona.
102
Frequency [GHz]103

YI & Doi ‘14• Synchrotron-self absorption iseﬀective below sub-mm.

Table 1. Results of observations.
Obs. date

Array

(1)
1985 Jul 28
1990 May 23
2001 Sep 28
2003 Apr 03–May 25
2003 Jun 19
2003 Dec 24

(2)
VLA-C
VLA-D/AVLA-CnD
NMA-D
VLA-A
VLA-Bν
(GHz)
(3)
22.5
22.5
22.5
95.7
8.46
43.3
22.5
14.9
8.46

Sν
(mJy)
(4)
< 5.0
< 3.3
1.9 ± 0.3
< 4.6
0.84 ± 0.08
2.0 ± 0.9
1.2 ± 0.3
0.81 ± 0.25
1.3 ± 0.1

σrms
(mJy beam−1 )
(5)
1.68
1.09
0.15
1.52
0.04
0.48
0.13
0.25
0.10

θmaj × θmin(arcsec×arcsec)(6)
1.5 × 1.1
5.6 × 3.9
3.8 × 1.7
8.1 × 6.1
0.35 × 0.25
0.35 × 0.14
0.56 × 0.31
0.88 × 0.44
1.7 × 0.8

φPA
(deg)
(7)
−20.0
59.0
72.3
−12.8
12.0
−30.2
−35.2
−39.3
−41.2

GHz Excess Sources? NGC 985
Col. (1) observation date; Col. (2) array configuration; Col. (3) center frequency; Col. (4) total flux density; Col. (5) image rms noise on blank sky; Cols. (6)–(7)synthesized beam sizes in major axis, minor axis, and position angle of major axis, respectively.

-101010000
10iFi [erg/cm2/s]
Flux density (mJy)-121000
101011• but, 10NGC 985
Corona (Thermal)
Corona (Thermal + Non-thermal)
Jet
ALMA (60 sec)
Data-11-13• Free-free emission from BLR clouds?

clouds required• self-absorbed Synchrotron jets?

100-141010-15

10-16

10-17

• but, the scale is ~500 rs (~0.01 pc).

10

• >100 times smaller than GHz-

1

Peaked Spectrum sources.

10-18
100.1
-19
10 1
010
10
1

100
10
Frequency[GHz](GHz)
Frequency
2

3
1000
10

4
10000
10Doi, YI,+ in prep.

Fig. 1. Radio-to-FIR spectrum of NGC 985 nucleus. Open and Filled symbols are data published by other authors and data newly-presented in the presentstudy, respectively. Negative detections are indicated by downward arrows. Lines connecting symbols indicate quasi-simultaneous observations. FilledSquares: our VLA observations with VLA-CnD at 22.5 GHz (AD456) and VLA-B at 8.46–43.3 GHz (AD489). Lower-peaked filled triangle: NMA
observation at 95.7 GHz as negative detection. Upper-peaked triangles: VLA-A observations; filled symbol at 4.89 GHz is data of Ulvestad & Wilson(1984) and reanalyzed in the present study; open symbol at 8.46 GHz is from archival data AN114. Open circles: VLA-C (AA48) and VLA-D/A hybrid(AB489, tapered to 100 kλ resulting in ∼ 4′′ at all frequencies) observations by Barvainis et al. (1996); 22.5-GHz data (negative detections) are newly
reported in the present paper. Lower-peaked open triangle: NVSS result (Condon et al., 1998). Open diamonds: Herschel PACS at 70 µm and 160 µm
toward the nucleus (Meléndez et al., 2014). Open squares: IRAS Faint Source Catalogue, version 2.0 (Moshir & et al., 1990) at 60 µm and 100 µm. Solidand dashed curves: dust model spectra for cases of the emissivity β = 1 (33.7 K) and β = 2 (27.1 K), respectively.

• Coronal Synchrotron Emission?
• but, corona size will be ~100 rs.
• Yes! We got ALMA time! We willobserve this source in ALMA cycle-3.

Summary• The origin of the accretion disk coronae is not well understood. Maybe

reconnection heated.
• Understanding of corona will be essential for further understandingof the relativistic iron K line.
• The MeV gamma-ray background flux from Seyferts will be animportant probe.
• Anisotropy will tell us its contribution.
• Coronal non-thermal synchrotron emission is another probe.
• X-ray & Sub-mm observations will be crucial.
• Stay tuned for the ALMA, NuSTAR, & ASTRO-H results