活動銀河中⼼核からのMeVガンマ線放射
Yoshiyuki Inoue (RIKEN)

MeVガンマ線研究会 @ 東大本郷, 2019-09-27

Active Galactic Nuclei (AGNs)
Blazar• >106 solar mass @ galactic

RQ AGNs
BlackHolecenterRadioGalaxy• Correlate with various physicalparameters of host galaxies• Gas accretion• brighter than host galaxies(AGNs)

Accretion
Disk

Relativistic
Jetimaginary picture ofAGN©NASA • Relativistic jets

• Hot Coronaeanalysis techniques revealed that the VHE -ray of Cen A is produce
208 is consistent with our results.
207

BL Lacs

MeV AGNs

The Astrophysical Journal, 827:55 (6pp), 2016 August 10-6

VLA AX1A
CGRO/COMPTELVLA AX1C
Fermi-LAT (2008-2016)
VLA AX2HESS (2004-2010)
VLA BX2
Synchrotron Core
Chandra AX1A
SSC Core
Chandra AX1C
Synchrotron AX2
Chandra AX2
EC AX2Chandra BX2Starlight spectrum
NED Core
Total AX2
NED Host galaxy
Total SSC+EC
Kataoka&Stawarz
Suzaku (2009)

Radio Galaxies

-6

FSRQs

ong with the models discussed in the text and parametrized as in Tables 2 and 3. In bothνFν [erg cm-2 s-1]

νFν [erg cm-2 s-1]

10 acceleration of electrons limited by10continuous (stochastic)
radiative losses (e.g., Stawarz & Petrosian 2008), or (ii) the-8-8
reduction of the IC cross-sectionin the Klein–Nishina regime
1010(e.g., Moderski et al. 2005). In case (i), the pile-up bump appears
at the maximum electronenergies for which the acceleration
-10
10
10-10
timescale equals the radiative loss timescale at the limit for theperfect conﬁnement of electrons within the emission zone (i.e.,-12-12
no particle escape). 10
However,the PL tail at lower electron
10
energies has to be relatively ﬂat in such a scenario,s º -d ln Ne¢ (ge ) d ln g-14
e = 0 - 1, which disagrees with the-141010
observation in Mrk421. Similarly, in case (ii), the necessary
condition for the formation of a pronounced spectral hardening
in the electron energy
10-16distribution is the dominance of IC
10-16
cooling over synchrotron cooling and a relatively narrow (within10
the frequency range) seed
distribution.
These require105photon 10
1015
1020
1025
1
ments contradict the conditions expected for Frequency
the Mrk421[Hz] jet inKataoka & Stawarzquiescence’16
Kataoka, YI’19(for which the synchrotron losses dominate theTanada,ICFigure 4. Broadband X-ray (NuSTAR; this paper) to high-energy γ-ray ( FermiJet &LAT
accretionin blazars
by NuSTAR
1547 losses and the soft photon distribution for the IC scattering is; Abdo et al. 2011b)
spectra ofobserved
Mrk421. Bow-ties
plotted in black denote
2. Overall
SED ofemission
Cen A obtained
from multi-wavelength data,
provided by theFigure
broadband
synchrotronof the jetthe Fermi-LATdata taken in different multi-frequency campaigns; the average(Steinleet al. 1998; ofSteinleitself). Therefore,CGRO-COMPTEL
while also considering
the extrapolationthe 2001), F ermi-LAT, HES
source spectrum during the period of a source quiescence (from 2008 August 5
to 2010 February 20) is shown as a magenta bow-tie. Dashed magenta lines
al. 2002;
Hardcastle
Fermi-LAT spectrumof thesource etto al.
the2007;
X-rayGoodger
regime, etweal. 2010), and Chandra (usemark the extrapolation of the best-ﬁt power-law model to the average Fermithe core
represented
the red datasolid line, and the EC/starligh
argue that the hard
X-rayemission,excess foundin thebyNuSTAR
LATdata (γ-ray photon index of 1.78 ± 0.02).
knot,
by theblue diamonds and the blue bz = 2.69
indeed represents
therepresented
low-energy
tail blueof solid
the line.
IC The(SSC)
respectively. The starlight emission from the host galaxy of Cen A is repcomponent.
To investigate the physical origin of the detected excess
EC/starlightmodelenergy
for theofkpc-scale
emission with the BX2 knot, rFrom the observed
SSC photon
hnSSC  jet20 keVemission, we compiled the broadband X-ray (NuSTAR; thisthe samePL
as thatin theleft panel.
The blackand a steep broadband
electronenergy
distribution,the diamonds and the black bowork) and high-energy γ-ray ( Fermi-LAT; Abdo et al. 2011b)
respectively.
corresponding minimum
electron Lorentz factor is roughly
data in a ν−ν Fν representation, as shown in Figure 4.
Bow-ties plotted in black denote the Fermi-LAT data taken⎛ B¢ ⎞-1 4 ⎛ d ⎞-1 43⎜⎟during different multi-frequency campaigns; the average source⎟.
ge,min ~ 10 ⎜(1 )
⎝⎠
⎝
⎠
0.1
G
10spectrum during the period of a source quiescence (from 2008
209
4. DISCUSSION
August 5 to 2010 February 20) is shown as a magenta bow-tie.
The radiative cooling timescale for such low-energy electrons210
One of the possible reasons for the detection of the GeV hardness i
The dashed magenta lines mark the extrapolation of the best-ﬁt
dominated by the synchrotron process is then
211 the core emission above a few MeV. This results from the small max
PL model applied to the average Fermi-LAT data (γ-ray-7 4-3 4photon index of Γγ∼1.78±0.02; Abdo et al. 2011b) with 1σ⎛ d ⎞values
212 where the⎛ otherof FR I are max = 105 for the core oB¢ ⎞observed
7⎜⎟⎟s,tcool (ge,min) ~ 10 ⎜(2 )uncertainty. The excess hard X-ray emission detected in the213 the core ofM87⎝ 10et⎠ al. 2009b), and max = 108 for the core o⎝ 0.1
G ⎠(Abdo
Sbarrato+
Kimura+’19
analyzed NuSTAR data agrees well with the extrapolationof the ’16

Low-luminosity AGNsRadio-quiet AGNs

Richards+’06
Fig. 10.—Quasar SED diagnostic plot. Shown in gray are the Elvis et al. (1994) radio-quiet (solid) and radio-loud (dashed) mean SEDs. The colored lines indicate
typical spectral indices in the radio, optical, and X-ray using the same sign convention. Also shown is the typical radio-to-optical spectral index for radio-loud quasars
and the range of optical–to–X-ray spectral indices. Studies in different bands tend to use different sign conventions for spectral indices and jargon to describe them (e.g.,steep/red /soft). The top panel shows f" , while the bottom panel shows "f" . The x-axis is labeled as log (") (bottom), and wavelength, energy, and temperature (top ).

• cm-radio: jet, galactic CRs

and we have taken LBol /LEdd to be unity. This synthesis of multiple
scaling
relations will have considerable scatter, and many, if not•most, AGNs will be accreting at much lower Eddington ratios.
However, we have found that a value of (LBol /LEdd ) ¼ 1 works
well and has the nice feature that it represents the minimum hostgalaxy• contribution that must be accounted for (smaller ratios implying relatively more luminous hosts).
This process sets the relative scaling of the host galaxy in themm-radio : ?

IR : dust (>~0.1 pc)• opt: accretion disk (<~0.1 pc)

Using the relative scaling of the elliptical galaxy (host) template•with respect to the observed quasar (plus host) SED, we cans any
determine the fractional contribution of the host galaxy atother wavelength. To assess the importance of the host galaxy
correction where it matters most, we determine the ratio of hostgalaxy• to total luminosity at 1.6 !m in the rest frame, where theelliptical template spectrum has its peak. At 1.6 !m, we find thatthe host galaxy contributes between 30% and 38% of the total

X-ray: disk corona (~10 r )Gamma-ray : ?

Millimeter Excess?
10-12-1310
High-frequency excess in radio spectrum of NGC 985

10-14[Vol. ,• If a AGN corona is magnetized,
Table 1. Results of observations.

synchrotron radiation is expected
Obs. dateArray(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-B

ν
(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 × 0.8φPA(deg)
(7)
−20.0
59.0
72.3
−12.8
12.0
−30.2
−35.2
−39.3
−41.2

(Di Matteo+’97; YI & Doi ’14, Raginski & Laor ‘16)

νFν [erg/cm2/s]

810-15

IC 4329A
B=1032 G
B=10 G
B=1032 G w/ non-th
B=10 G w/ non-th
ALMA (60 sec)

10-16
10-17
10-18
10-19

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.

10-20
10-21 1
10102
Frequency [GHz]10000

YI & Doi ‘14• Possible mm excess

1000
Flux density (mJy)103(e.g., Antonucci & Barvainis’88; Barvainis+’96; Doi &Inoue ’16; Behar+’18)

100

10

• Contamination of extended components

1• Lack of multi-frequency observations.

0.1
1

10

100
Frequency (GHz)

1000

10000

Doi & YI ‘16

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 present

Fν [mJy]

cm-mm spectrum of IC 4329A Core
102101IC 4329A
10010-1 010VLAATCAALMAHybrid Corona
Jet
Total

101
Frequency [GHz]• Clear mm excess from cm spectrum

102

YI & Doi ‘18

Coronal parameters
102• Hybrid corona model (YI & DoiFν [mJy]’14)101• Non-thermal electron fraction :η = 0.03 (fixed)

IC 4329AVLAATCAALMAHybrid Corona
Jet
Total

10010• Non-thermal spectral index

p = 2.9• Size: 40 rs-110011010Frequency [GHz]2YI & Doi 2018

• B-field strength : 10 GOther RQ AGNs

Fν [mJy]

101NGC 985

NGC 1068

10010NGC 985-110-2 010VLAATCAALMAHybrid Corona
JetTotal

101102Frequency [GHz] YI & Doi 2018

YI+’19• NGC 985 is detected. NGC1068 is also marginally detected.
• 9 more RQ AGNs are observed in the ALMA cycle-6.

Fν [mJy]

cm-mm spectrum of IC 4329A Core102101IC 4329A
10010-1 010VLAATCA
ALMAHybrid Corona
JetTotal

101
Frequency [GHz]102

YI & Doi ‘18• Non-thermal electrons should exist in the coronae

Generation of High Energy Electrons in Coronae
Acceleration & CoolingElectron Spectrum

YI + ‘19• 1st-order Fermi acceleration can produce the observed

electrons with an injection index of 2

• Other mechanisms may be difficult.

High energy emission from AGN coronae

YI +’19• MeV emission is expected, but no GeV emission due to pair creation• Protons would also be simultaneously accelerated.
• generation of neutrinos (see also e.g., Begelman+’90;Stecker+’92;Kalashev+’15;Murase+’19)

Cosmic High Energy Background

YI + ‘19• RQ AGNs can explain X-ray, MeV gamma-ray, & TeV neutrino background.
• But, if both protons and electrons carry ~5% of the shock energy and gyrofactor is 30.

●Theposttr
ia
lpv
aluei
scalco
mpar
in
gt
hi
spv
alu
ewi
thbackgroun
dhots
pots.

IceCube Hottest SpotHottestPointinNort
hernHeRA= 40.
87°,Dec= 0.
30°
n =61.
45,γ= 3.
411si
gnal

NGC1068Pv
al= 6.
45,TS= 25.
34⇒ 9.
9HottestPoi
nti
nSout
hernH
Ra= 350.
18°,dec56.
45°
n =17.
75,γ = 3.
34si
gnal

Pv
al=5.
37,TS= 19.
95⇒ 75%
IceCube 2019 (ICRC)
YI +’19bNeutrino Telescopes – March 22nd 2019

• Type-2 Seyfert NGC 1068 is reported at 2.9-σ.

• Corona can be a neutrino production site above several TeV.

Summary• MeV emission is expected from various AGN populations.
• non-thermal electrons exist in coronae• MeV emission is expected also from radio-quiet AGNs
• Radio-quiet AGNs may be responsible for cosmic X-ray, MeV

gamma-ray, and TeV neutrino background fluxes.

• NGC 1068, type-2 Seyfert, is the hottest spot in the IceCubedata.

• MeV is a key for testing the model.