The mystery of the MeV gamma-ray
emission from gamma-ray binary systems
RIKEN, High Energy Astrophysics
Laboratory(← phD student in IPMU,
Takahashi group untill last March)

Hiroki Yoneda

2 / 54

Compact Binaries in Universe
About 70% of X-ray sources in our Galaxy arebinary systems that contain BHs 102
or NSs (Grim+02)
Andrzej A. Zdziarski and Marek Gierliński
Credit: NASA/R. Hynes

Zdziarski&Gierlinski04

Standard picture:
Fig. 1. Spectraof the soft state of 1996 June and of the average hard state of Cyg X-1. The
models(solid curves) in both states consist of hybrid Comptonization of disk blackbody
・A compact object captures material
froma companion starphotons, Compton reflection and fluorescent Fe K emission. The dashed curves give the model
spectra before absorption. We also show the upper limit from the EGRET observations in the・Its gravitational energy is efficiently
toofradiation
hard state converted
and an expected sensitivity
GLAST, see §2.2 for details. See astro-ph for color
48)10), 26)

versions of this and subsequent figures.

From the 2000s,stateseveral
binaryspectrum of Cyg
X-1 shown systems
in Figure 1, with the components of the fit shownin Figure 2(b). We see that Comptonization by nonthermal electrons dominates atthat cannot be explainedE bythis picture, were discovered>∼ 10 keV. The Compton reflection and Fe K fluorescence are present as well, andtheir strength, the ionization of the reflector, and the degree of relativistic broadening

4 / 54High Energy Emissions From Binaries
Owing to Fermi, HESS, MAGIC, VERITAS…,
GeV/TeV emissions from binaries have been discovered!

https://fermi.gsfc.nasa.gov/science/eteu/binaries/figure3.jpg

Gamma-ray Binaries

https://www.spacetelescope.org/images/heic0211i/

Microquasars

https://hard-sf.com/pulsars-of-black-widows-and-redback-spiders/

https://scitechdaily.com/satellites-monitor-the-colliding-windsof-o-type-stars/

Red back, black widow

Colliding-wind binary

7 / 54

Gamma-ray Binary Systems
Sub-class of high-mass X-ray binaries with these features,• Dominant non-thermal emission up to the TeV band
• Their SEDs have peaks beyond 1MeV

➔ Completely different features from X-ray binaries !

A&A 565, A38 (2014)

LS 5039PSR B1259-53

Collmar 2014

Fig. 9. X-ray to Te
The COMPTEL sodata) for the INFC a
combined with sim(Suzaku, Takahashi(Fermi/LAT, Hadas
band (HESS, Ahara high-energy SE
shows that 1) theergies above 1 keVation dominance i
gies. The lines –X-ray spectra repreof Takahashi et al.
tern of LS 5039. T
their measured X-ra

Fermi collab. 2011
Name

Star

LS 5039O

FGL J1018.6-5856

O

LMC P-3O

LS I +61 303

Be

HESS J0632+057

Be

4FGL J1405.1-6119 (Corbet+19)O

PSR J2032+4127

Be

PSR B1259-53

Be

Compact
objectOrbitalall available COMPTEL data of this sky
the INFC period.
For INFC the SED suggests a strong
spectral Period

break between the two bands with a drop in flux by a factor of 5 the known but unidentified COMPTEL
3.9 day
the counterpart of LS 5039.
between 30?MeV and 100 MeV.
In general, the COMPTEL measurements shed light on an inAs in previous analyses (e.g., Col? of the LS 5039 SED where the maximum16.6
teresting regionof the day
significant MeV source that is consiste
high-energy emission of LS 5039 occurs and where significant of LS 5039, which in the COMPTEL?
10.2 dayspectral changes
are happening. Therefore these COMPTEL
a kind of stable and steady flux level. B
results add important information on the emission pattern of sured Fermi/LAT spectra of Fermi-dete? so provide additional constraints for modeling
26.5
LS 5039, andthe day
COMPTEL error box into the COMPTE
to be the most likely counterpart. This i
microquasar.
?
315.5 byday
extrapolating the measured Suzaku
MeVband. Assuming no spectral break
6. Discussion?
13.7 daygies, the extrapolations reach similar fl
In recent years, after new γ-ray instruments became opera- COMPTEL fluxes, for the orbit-averag
143
pulsarthe ground-based Cherenkov telescopes
50 yearorbit-resolved, analyses.
tional –ms
in particularOrbit-resolved analyses provide th
HESS, MAGIC, and VERITAS and the γ-ray space telescope
43 ms
3.4
dence that GRO J1823-12 is the cou
Fermi– , apulsar
new class of γ-ray emitting objects emerged:
the year

Unkn

ure
t
a
N
n
ow

r

a
s
l
u
P
d
con
e
s
i
l
l
i
M

ek
e
W
~
Day

Year

8 / 54

Standard Pictures

Dominant Non-thermal Emission of Gamma-ray Binaries
ERSPECTIVES➔ How are particles accelerated ?
Electron/proton-proton interactions
star
Be Pulsar
starwith+Bepulsar

Electron-photon interactions

Microquasar model
Microquasar

Pulsar withmassivemodelstar
Pulsarwind

Cometary radio emmission
PulsarRelativistic jets

Pulsarγ-rays/υ

Compact objectof center
PulsarMassive star

Disk outflow

A

Accretion disk
Ultraviolet emission
and massive
clumpy wind

Be starMirabel 2012

Ultraviolet emission

Massive star

γ-rays/υ

B

γ-rays/υ

C

ObserverInteraction
betweena denseInteraction
betweenstellarGamma-raybinaries.
Pulsar winds are
powered by the High-energy
rapid rotation of mag-Emission
LS 5039 andfrom
1FGL J1018.6–5856).
(B) Microquasars
are poweredby compact
netized neutron stars. Gamma rays can be produced either by the interaction of objects (neutron stars or stellar-mass black holes) via mass accretion from a comBHprotons
jets in the disk panion star. When the donor starwinds
andstarpulsar
windsUV flux anddisk
andparticles
pulsartherelativisticof thewinds
pulsar wind with the outflowing
is a massivewith a high-density
or・PSRenvelopeB1259-53
of a Be star (A) (e.g., PSR B1259–63 and LSI +61° 303), or by their wind, gamma rays can be produced by electron-proton and/or electron-photon
interaction with UV photons from a very massive main-sequence star (C) (e.g., interactions. ν, neutrinos.
・PSR J2032+4127

time variation of flux at different wave-

Which is true?? ➔ Openquestion still…
5039), but it is not clear whether 1FGL

what different orbital modulation may oper-9 / 54

New Question: MeV emission ?

. Results of the power-law fitting of the COMPTEL spectra
MeV) for the two orbital phase intervals INFC and SUPC.

rvations
data
NFC
UPC

Photon index(α)
1.44 ± 0.29
1.77 ± 0.35

I0 (at 5 MeV)
(10−6 cm−2 s−1 MeV−1 )6.94 ± 1.61
4.47 ± 1.31

10 2

χmin

50.23

0.06

5039
The errors are 1σ (χ2min + 2.3 for 2LSparametersof interest).
0
30

25

20

15

10

PKS 1830-210

5Integ. Flux [10-5 ph cm-2 s-1]

Collmar&Zhang2014 re-analyzed the COMPTEL data of a
gamma-ray binary LS 5039, a brightest one in our galaxy
W. Collmar and S. Zhang: LS 5039 – the counterpart of the MeV source GRO J1823-12
They
found
strongMeV
emissionfrom LS 5039
d S. Zhang: LS 5039 – thea
counterpartof theMeV source
GRO J1823-12
Collmar&Zhang2014
3

10

5
2

30
1

25

LS 5039
20
15

10

0

5

PKS 1830-210

TEL data cover the time period between July 12,-5 1991-5uary 25, 2000. The COMPTEL measurements therefore∼3500 days before and ended ∼375 days before the time-10
-10
JD 2 451 943.09 ± 0.10 (equal to February 2, 2001),
for
0
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
2
Casares et al. (2005) determined the applied ephemeris.
Orbital Phaseng their period uncertainty (∆P) of 0.00017 days, yields
e uncertainty ∆Φ (∆Φ = (∆T × ∆P/P)) of ∼0.15 at Fig. 8. Orbital light curve of LS 5039 in the 10−30 MeV COMPTELe)
MeV(right) VP
maps,
generated
coordinates(l,ofb),allshow
the light
statistical
for the sum
data. The
curve isevidence
folded with the orbital
VPand
5.0 10−30
and 0.017
at CGRO
907.0,
the first in
andgalactic
last band
period
∼3.9fordaysa andgivensource)in phase withbins ofThe observations
contour lines
startLSat5039
a detection
significance(1 ofd.o.f.
known
a 0.2.
stepTheof two broader
TELof thesky region.
On average,of 3σ◦phase PKS
periods,
defined as(square)
INFC andare
SUPC,
are indicated.
seerror(diamond,is ∼0.08 during
the COMPTEL
re- quasar5039
l/b: 16.88/−1.29◦ ) mission
and the withlensed1830-210
indicated;i.e., A flux induring the INFC period is obvious. In the phase bin containthe orbital solutionof TheCasares
et al.PKS(2005),
suggesting
COMPTEL
sources.
quasar1622-297
anda a crease
possiblesource at the Galactic center, both out
ing the inferior conjunction, the source is roughly three times brighter
inning0.2.
Subsequently,fitting.
we analyzed
the COMPTEL
ount
inofthesimultaneous
The 10−30
MeV band yields the highest detection significance (7.8σ)

The angular resolution of COMPTEL is few degrees, but the
MeV flux is modulated along the binary orbit of LS 5039!

than in the phase bin containing the superior conjunction. In general the10 / 54

New Question: MeV emission ?
• Both the microquasar model and the pulsar wind model seemdifficult to explain the MeV emission…

Dubus, Lamberts, Fromang: Modelling gamma-ray binary emission based on relativistic hydrodynamics
A&A 565, A38 (2014)

Pulsar wind model (Dubus+2015)

0 GeV. Reproducing both the hard INFC spectrum
parable levels of X-ray and VHE emission turned
fficult. The models explored in §4 all cut o↵ aroundcause the high-energy particles responsible for thisstrongly cooled by synchrotron losses. Lowering
Fig. 9. X-ray to TeV γ-ray SED of LS 5039.
The COMPTEL soft γ-ray spectra (sum of all
the mean magnetic field, hence increases the VHEdata) for the INFC and SUPC orbital phases are
so lowers the X-ray flux relative to the VHE gammacombined with similar spectra from the X-ray(Suzaku, Takahashi et al. 2009), the MeV/GeV
re is a trade-o↵ between having enough synchrotron(Fermi/LAT, Hadasch et al. 2012), and the TeVband (HESS, Aharonian et al. 2006a) to build
ccount for the X-ray flux, and lowering ⇣b to enablea high-energy SED of LS 5039. The SED
shows that 1) the emission maximum at ennergy particles to radiate enough VHE photons. As
ergies above 1 keV and 2) a switch in radi§4.5, changing ⇠ has little influence on the VHE
ation dominance is occurring at MeV energies. The lines – solid and dashed – in the
we kept ⇠ = 1. Limited exploration showed the best
X-ray spectra represent the model calculationsof Takahashi et al. (2009) on the emission patas obtained by slightly lowering ⇣b to 0.5 and bytern of LS 5039. They do not present a fit totheir measured X-ray spectra.
ection slope s = 1.5 instead of 2.
nation has an e↵ect on both lightcurves and spectral
the INFC period. For INFC the SED suggests a strong spectral all available COMPTEL data of this sky region by assuming thatheVHE
variations
arebymore
pronounced
break
betweenspectral
the two bands
with a drop in flux
a factor of
5 the known but unidentified COMPTEL source GRO J1823-12 isthecounterpart of LS 5039.
between 30 MeV
andhigh
100 MeV.
althoughtooaninclination
resultsina
INFC
In general, the COMPTEL measurements shed light on an inAs in previous analyses (e.g., Collmar 2003), we found aWhatphysicsarewemissing? orwewithneedanother model ?
SED(Fig.
where theof thehterestinga fluxregion
thatof theis LS
too5039
low8).maximum
A highinclination
significant MeV sourcethat isdoconsistent
the sky position
emission of LS 5039 occurs and where significant of LS 5039, which in the COMPTEL 10−30 MeV band showsnhigh-energy
a pronounced
dip of emission
atCOMPTEL
inf = 0.77.
spectralchanges are happening.
Therefore thesea kindTheof stable and steady flux level. By extrapolating the mea-

11 / 54

New Question: MeV emission ?
• In both cases, it is assumed that Fermi acceleration takes place• In general, the acceleration is described phenomenologically as

qBc
γ·emec =ηη : acceleration efficiency
B : magnetic field• In Fermi acceleration (DSA), η ≃ 10 (V/c)−2 ≳ 10.
2• When γe,MAX is determined by the balance between the acceleration andthe synchrotron cooling, the synchrotron peak is (Aron 2012)hν = 236 MeV × η −1
• So, in Fermi acceleration, hν < 20 MeV ,but gamma-ray binaries shows hν ∼ 20 − 30 MeV

How to explain such an extreme acceleration ?

12 / 54

MeV emission from other sources?
Gamma-ray binaries and related systems• COMPTEL detected the MeV emission

from LS I 61°+303 (?)

PSR B1259-53 shows a very bright MeV/GeV flare ~ 30 days after the periastron.
PSR B1259-53
Fermi collab. 2011

Flux [ 10-6 ph cm-2 s-1 ]•Dubus 2013

1.6
1.4

Peak
Luminosity
1.2~1 8 x 1035 erg s-1
0.8
 comparable !!
0.6
Spin-down
Luminosity
0.4
35 erg s-1
~
8.3
x
10
0.2
Fermi, after flux change
Fermi, 8 months

00

0.2 0.4 0.6 0.81

1.2 1.4 1.6 1.8 2
Phase

The MeV emission in gamma-ray binaries
is a challenging
subject
Fig. 5 Observationsof LS I +61 303. From
top to bottom:

13 / 54

Today’s talk
• Gamma-ray binaries are new particle accelerator in the Universe.
• The acceleration/emission mechanism are unclear.
• Some of them show the MeV gamma-ray emission.
• To tackle with these questions observationally,

we analyzed LS 5039, the brightest gamma-ray binary.
1. Multi-band spectrum analysis using NuSTAR&Fermi(Yoneda et al. in prep.)
2. Pulsation search in the hard X-ray band
(Yoneda et al. 2020, PRL, arXiv:2009.02075)
3. Magnetar binary hypothesis with reconnection

14 / 54

Today’s talk
• Gamma-ray binaries are new particle accelerator in the Universe.
• The acceleration/emission mechanism are unclear.
• Some of them show the MeV gamma-ray emission.
• To tackle with these questions observationally,

we analyzed LS 5039, the brightest gamma-ray binary.
1. Multi-band spectrum analysis using NuSTAR&Fermi(Yoneda et al. in prep.)
2. Pulsation search in the hard X-ray band
(Yoneda et al. 2020, PRL, arXiv:2009.02075)
3. Magnetar binary hypothesis with reconnection

since the
15 / 54
significa
observed
obtainedof Figurwhich is obtained from the phase-averaged Suzaku spectrum.
range of
Also, phase-resolved ASCA spectra were fit using NH frozen at
the gamma-ray
phase-averaged value.
As seenin Figure
1, the photon
indices
LS 5039 is the brightest
binarywitha shortorbitalperiod is shown
open circles represent the Suzaku observation. Fitting parameters are shown in
Table 1.

Gamma-ray Binary System LS 5039

y sin i (light-sec)(3.9 day) → Observable deeply over its entire orbit(a)60Distance：2.5 ± 0.1 kpc (Casares+05)

Φ = 0.046

40

SUPC

Φ = 0.0

Φ = 0.1

20−20

O starΦ = 0.4

Φ = 0.8

Φ = 0.5−60
observer−80−80

Φ = 0.9

Φ = 0.3

−40

−60

−40

(b)

Eccentricity：0.35 ± 0.04 (Casares+05)

Φ = 0.20Companion：22.9+3.4−2.9 M⊙, O star

Φ = 0.7

Compact Star： > 1.5 M⊙ (Casares+05)
It is unknown whether the compact star is a BH or NS.

INFC

Φ = 0.6

Φ = 0.670

−20

0

20
40
60
x sin i (light-sec)

Remarkable Reproductivity in soft
X-rays➔ Non-accreting system is favored➔ pulsar wind system?
Kishishita+09

16 / 54

SED of LS 5039

A&A 565, A38 (2014)~ 3 years Fermi data
(Hadasch+12),

But we have 11 years
Fig. 9. Xdata now! The COMdata) for th
combined(Suzaku, T(Fermi/LA
band (HEa high-en
shows thaergies abo
ation domgies. The
X-ray speof Takahatern of LS
their meas

Suzaku data
(Takahashi+09),
But we have
NuSTAR data now!

Collmar 2014

the INFC period. For INFC the SED suggests a strong spectral
break between the two bands with a drop in flux by a factor of 5
between 30 MeV and 100 MeV.

all available COMPTEL data o
the known but unidentified CO
the counterpart of LS 5039.

Let’s update the SED using the latest data!

17 / 54

NuSTAR observation
NuSTAR observed LS 5039 in 2016
• The exposure is 350 ks, which covers one-full orbit of LS 5039•

data and folded model
0.1

normalized counts sï1 keVï1

Flux = 2.34 0.02
0.01

Source10-11 erg cm-2 s-1
Γ = 1.627 0.010

10ï3

10ï4

Background(dataïmodel)/error

10ï5
4
2
0
ï2
ï4
5

10

20

50

Energy (keV)

The phase-averaged spectrum is well-described by a single powerlaw,
up to 80 keV

of Fiwhich is obtained from the phase-averaged Suzaku spectrum.
54
Also, phase-resolved ASCA spectra were fit using NH frozen at 18 /range
is shothe phase-averaged value. As seen in Figure 1, the photon indices

Orbital Light Curve(a)

Calculated the flux by dividing data with a bin width of 4 ks
Compared the results with the previous Suzaku results
12● Suzaku/XIS (1 - 10 keV, 2007) ● Chandra (2004)●● XMM (2003, 2005) ● ASCA (1999)— 3—10 keV flux at 2016 (NuSTAR)— 3—10 keV flux at 2007 (Suzaku)
1σ orbital phase error
between Suzaku and NuSTAR

10

8

6

0
0

0.2

0.4

INFC

2

Apastron

4

SUPC

Flux (10-12 erg cm-2 s-1)(

0.6
Orbital Phase

Kishishita+09
0.8

Figure 2. (a) Orbital light curves in the energy range of 1–10 keV. Top: Suzaku XIS data wi
1light curve but shifted by one orbital period (open circles). Bottom: comparison with the pasteach bin of 1 ks, and green with each bin of 2 ks), ASCA (red with each bin of 5 ks), and Cha
values. The blue solid lines show periastron and apastron phase and the red dashed lines sho(b) Close up in 1.2 ! φ < 1.8.

・From apastron to INFC, the 3-10 keV flux are different between the
NuSTAR and Suzaku
・Doppler boosting? Another spectral component in hard X-rays?

19 / 54

11 years Fermi observation (Pass 8 data, 2008–2019)

10−10

INFC — 0.45 < φ < 0.9
SUPC — 0.0 < φ < 0.45, 0.9 ＜φ < 1.0
y sin i (light-sec)

E2 dN/dE (erg cm-2 s-1)

y
r
a
n
i
m
i
l
e
pr

60
Φ = 0.046

40

SUPC
20
Φ = 0.2

0−20

O starΦ = 0.4

observer−80−80

Φ = 0.8

Φ = 0.5−60

10

Φ = 0.9

Φ = 0.3−40−11

Φ = 0.0

Φ = 0.1−60−40

Φ = 0.7

INFCΦ = 0.6

Φ = 0.670

−20

0

20
40
60
x sin i (light-sec)

10−12
102

103
Energy (MeV)104
105
See Yoneda et al. in prep.

The spectrum in INFC is well-described bypowerlaw + cutoff-powerlaw

20 / 54

Orbital Light Curve

6.8. SEARCH FOR TIME VARIABILITY
Eγ = 100.0 - 220.0 (MeV)

y
r
a
n
i
m
i
l
e
pr
−9

0.2

0.15
0.1
0.05
0.2

0.4

0.8
1
1.2
Orbital Phase

1.4

1.6

1.8

−12

E2 dN/dE (erg cm-2 s-1)

0.2 ×10
0.18
0.16
0.14
0.12
0.1
0.08
0.06
0.04
0.02
0
0
0.2

0.6

Eγ = 220.0 - 460.0 (MeV)−9

E2 dN/dE (erg cm-2 s-1)

2

50 ×10
45
40
35
30
25
20
15
10
5
0
0
0.2

0.25

0
0

0.4

0.6

0.8
1
1.2
Orbital Phase

1.4

1.6

1.8

Eγ = 460.0 - 1000.0 (MeV)

×10−9

−12
20 ×100.14

E2 dN/dE (erg cm-2 s-1)

E2 dN/dE (erg cm-2 s-1)2

−90.1×10
0.09
0.08
0.07
0.06
0.05
0.04
0.03
0.02
0.01
0
0
0.2

E2 dN/dE (erg cm-2 s-1)

E2 dN/dE (erg cm-2 s-1)

0.3 ×10

0.12
0.1
0.08
0.06
0.04
0.02
0
0

0.2

0.4

0.6

0.8
1
1.2
Orbital Phase

1.4

1.6

1.8

2

18
16
14
12
10
8
6
4
2
0
0

0.2

97

Eγ = 1000.0 - 2200.0 (MeV)

0.4

0.6

0.8
1
1.2
Orbital Phase

1.4

1.6

1.8

2

1.6

1.8

2

Eγ = 2200.0 - 4600.0 (MeV)

0.4

0.6

0.8
1
1.2
Orbital Phase

1.4

Eγ = 4600.0 - 10000.0 (MeV)

0.4

0.6

0.8
1Yoneda1.2
1.4 et
1.6 al.
1.8 in 2prep.
See
Orbital Phase

Figure 6.8: The orbital light curve in different energy intervals.

Peak is at φ~0.0, but the amplitude changes with the energy21 / 54
Figure 6.8: The orbital light curve in different energy intervals.

Ratio of the variable component to the total

0.8
0.6

0.2

(Flux

- FluxMin)/(Flux

0.7

Max

Max

+ FluxMin)

y
r
1
a
n
i
m
i
l
e
pr
0.9

0.5
0.4
0.3
0.1
0

102

Spectral Analysis

Low-energy comp.

3

10
Energy (MeV)104
See Yoneda et al. in prep.

High-energy comp.

See Yoneda et al. in prep.

There
are
spectralcomponents.
Figure 6.9: The ratioof (F− Fmin) to (Fmax+ Fmin ). Fmax and Fmin are th
max two
These have different orbital dependence!

nd minimum flux in the light curves of Figure 6.8.

22 / 54

Updated SED of LS 5039
φpeak = ~0.7 (INFC)

φpeak = ~0.0 Small orbital(periastron) dependence φpeak = ~0.7 (INFC)

10−9— INFC (0.45 < φ < 0.9)
— SUPC (0.0 < φ < 0.45, 0.9 < φ < 1.0)

ry
a
n
i
prelim−10ν Fν (erg cm-2 s-1)

10

10−11

10−12

10−13 3
10

104

5

10

6

10

107

8

9

10
10
Energy (eV)

10

10

1011

1012

13

10

1014

See Yoneda et al. in prep.

28 / 54

Updated SED of LS 5039
φpeak = ~0.7 (INFC)

φpeak = ~0.0 Small orbital(periastron) dependence φpeak = ~0.7 (INFC)

10−9

ry
a
n
i
prelim−10 Synchrotronν Fν (erg cm-2 s-1)

10

— INFC (0.45 < φ < 0.9)
— SUPC (0.0 < φ < 0.45, 0.9 < φ < 1.0)?

Fifth component, or
high-energy tail ofthe MeV component?

+ IC emission

Emission close to
the neutron star?

???
10−11

?

10−12

10−13 3
10

104

5

10

6

10

107

8

9

10
10
Energy (eV)

10

10

1011

At least, four spectral components

1012

13

10

1014

See Yoneda et al. in prep.

29 / 54

Comparison with proposed models

14

Yoneda et al.
10−9

10−10

10−10
ν Fν (erg cm-2 s-1)

ν Fν (erg cm-2 s-1)

ry Pulsar wind model ①
a
n
i
m
i
l
e
r
p
10−9

10−11

10−12

10−11

10−12

Dubus et al. 201510−13 3
10

104

105

106

Takata et al. 2014

107

108
109
Energy (eV)

1010

1011

1012

1013

10−13 3101014

Jet-like stucture

10−9

105

106

107

108
109
Energy (eV)

1010

1011

1012

1013

1014

12

13

14

Two IC component

10−10ν Fν (erg cm-2 s-1)

ν Fν (erg cm-2 s-1)

104

10−9

10−10

10−11

10−12

10−11

10−12

Takahashi et al. 2009
Khangulyan et al. 2008
10−13 310

Pulsar wind model ②

4

10

5

10

6

10

7

10

Yamaguchi&Takahara et al. 2012
8

9

10
10
Energy (eV)

10

10

11

10

12

10

13

10

14

10

10−13 3
10

104

105

106

107

108
109
Energy (eV)

10

11

10
10
10
10
See Yoneda
et 10
al. inprep.

X-ray/TeV are explainedby the pulsar model, but MeV/GeV is not explained
Figure 15. The comparison between the updated SED and proposed models.

30 / 54

Possible interpretations for the MeV emission
10−9— INFC (0.45 < φ < 0.9)
— SUPC (0.0 < φ < 0.45, 0.9 < φ < 1.0)

ry
a
n
i
prelim10
ν Fν (erg cm-2 s-1)

−10

10−11

10−12

10−13 3
10

104

5

10

6

10

107

8

9

10

13

10
10
10
1011
1012
10
1014
Energy (eV)See Yoneda et al. in prep.

① Synchrotron emission in strong B ﬁeld
・peak at 20-30 MeV → η< 10・Not to overestimate the TeV emission→B≳3G
・To explain the hard photon index→ hard electron spectrum (< 2)→ eﬃcient acceleration in strong B ﬁeld ?

② Inverse Compton with GeV eSeed photons are UV ones (~10 eV)from the optical companion＋ Upscattered photons are MeV→ Electrons should be 〜GeV→ In shock regions, many GeVelectrons in addition to TeV electrons31 / 54

Today’s talk
• Gamma-ray binaries are new particle accelerator in the Universe.
• The acceleration/emission mechanism are unclear.
• Some of them show the MeV gamma-ray emission.
• To tackle with these questions observationally,

we analyzed LS 5039, the brightest gamma-ray binary.
1. Multi-band spectrum analysis using NuSTAR&Fermi(Yoneda et al. in prep.)
2. Pulsation search in the hard X-ray band
(Yoneda et al. 2020, PRL, arXiv:2009.02075)
3. Magnetar binary hypothesis with reconnection

32 / 54

Previous Work in Pulse Search
The pulsation is good evidence of existence of NS…
Previous Works
Non-detection in radio band (4.1 - 14.5 μJy, McSwain+11)
Non-detection in soft X-ray band (0.3 - 10 keV, Rea+11)→ Pulses might be absorbed by stellar winds?
Higher energy band is better• Less stellar wind absorption in higher energy band
• In hard X-rays, we have long observation data of Suzaku,

NuSTARWe focus on hard X-ray band (> 10 keV) for pulsation search33 / 54y sin i (light-sec)

1st Step: Timing Analysis by diving data
60

Effect of orbital motion

Φ = 0.046

40

SUPC

Φ = 0.0

Φ = 0.1

・Orbital velocity of NS is ~ 0.001 c

20
Φ = 0.2

0

O star➔ smears the pulse signal

Φ = 0.9

Φ = 0.3−20−40

Φ = 0.4
Φ = 0.7

Φ = 0.5−60
observer

−80
−80

−60

−40

・Large parameter space,Φ = 0.8➔ it is difficult to search pulse with correcting theorbital modulationINFCΦ = 0.6

Φ = 0.670

−20

0

20
40
60
x sin i (light-sec)

Simple and Best Way
1. Divide the data into subsets with a time interval of Tsub.
Resolution of timing analysis (1/Tsub) > Orbital modulation (0.001/P)➔ Tsub < 1000 × Pulse Period
2. Apply Fourier analysis to each subset, and merge the result incoherently※ To get enough photons in subsets (>10 events), we focus on pulse signal < 1 Hz.
 
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37 / 54

Fourier Analysis with Suzaku 
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ΔT

prob. = 1e-3

Δ T = 4096 s
Δ T = 8192 s↑ Pulsation at 8.96 s ??

Δ T = 16384 s

We found a periodicity at 8.96 s with post-trial of 1.1×10-3

38 / 54

Fourier Analysis with NuSTAR
We applied the same analysis to the NuSTAR data (3–10, 10–30 keV)
E = 3 - 10 keV

E = 10 - 30 keV

prob. = 1e-3

prob. = 1e-3

ΔT = 4096 s

ΔT = 4096 s

prob. = 1e-3

prob. = 1e-3

ΔT = 8192 s

ΔT = 8192 s

prob. = 1e-3

prob. = 1e-3

ΔT = 16384 s

ΔT = 16384 s

No significant peak… We search for weak pulsed signal!

39 / 54

Z2 analysis
To check the peak at 8.96 s, we analyzed the Suzaku data with Z2 statistics.
Z2 statistics (De Jager+89)
A common technique to search a weak periodic signal
Unbinned likelihood analysis (better than ordinary chi-square evaluation)2
Zm=<latexit sha1_base64="9nEyQGhmKQ/BOjjbfJHBeXQLMSk=">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</latexit>
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sha1_base64="d2ZrVHRg4MB4lcOgaobDEBAIWok=">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</latexit>

2
N

l=m
X
l=1

0
@

X
i

ti
cos 2⇡l
P

!2

+

X
i

1. Make a folded light curve assuming a period.

ti
sin 2⇡lP!2 1

A ' log L

2. Calculate Fourier component of the obtained profile
3. Sum up the power of the component upto m-th harmonics.

➔

+

+

+

Relying on the Suzaku 8.96 s peak,
we constrain the period search range to 7-11 sec…

+ …

40 / 54

Sign of the pulsation at 9 s in the NuSTAR data(a) 300

Σ Z2 (m=1)

250

A sign of a pulse at 9.046s
with 7-11 s, ΔT = 10000 s,
post trial is 3.5×10-3

prob. = 1e-3
local prob. = 1e-5

200

150

Suzaku, 2007 Sep. (10-30 keV)

100

(b)

7

8

8.5

9

Period (s)

140
120

Σ Z2 (m=1)

7.5

9.5

10

10.5

11

prob. = 1e-3
prob. = 1e-2

local prob. = 1e-5

100
80
60
40

NuSTAR, 2016 Sep. (10-30 keV)

20
7

7.5

8

8.5

9

Period (s)

9.5

10

10.5

11

Suzaku (2007 Sep.)
P = 8.960 ± 0.009 s
NuSTAR (2016 Sep.)
P = 9.046 ± 0.009 s⇓(If this is real)
The compact star in LS 5039
is suggest to be a NS with
P ~ 9sPdot ~ 3×10-10 s s-1

mean of 8.0 when referring to a chi-square distribution of 8 (twice the maximum harmonic) dof. As described in themain text L.201, this gives the pre-trial probability of 1.7 ⇥ 10 11 .
41 / 54

The right panel of Figure 3 is the NuSTAR result. In this case, several peaks were found: one is around (aX sin ✓, e) ⇠(48 light-sec, 0.30) as indicated as (B), and several peaks are seen around aX sin ✓ ⇠ 62 63 light-sec as indicated as(C). These solutions have comparable significance, with Z2MAX ⇡ 67. However, the latter solutions, when combinedwith the optically derived system mass function, imply the system inclination of ✓ ⇠ 70 ± 6 , which is somewhat
withthe constraintof ✓ <
66 ± 2 [9] set byandthe lackof X-ray eclipses.
In addition, (B) is close to (A),
1. inconsistent
Assumeasetoforbitalparameters,
calculate
the
orbit
of
NS
though still somewhat inconsistent with each other. We hence consider that the solutions (C) are less likely than (B),have adopted
in Tablearrival
I in the maintext.to the time on NS
2. andcorrectthe (B)
photontime

3. apply Z2 analysis to corrected data.
90% Error Size

0.36

65

0.34

(A)

Eccentricity

0.32

60

0.3
0.28

55

0.26
0.24

NuSTAR,NuSTAR
10—30 keV, m=4
0.38

65

0.32

60

0.3

(C)

0.28
0.26

50
79

0.22
45

0.2

45

0.18
Table 5.2: Best-fitting
Table 5.2:values
Best-fittingof the orbitalvalues ofparameters
the orbitalobtained
parameters
fromobtained
Suzaku/NuSTAR
from Suzaku/NuSTAR
ob35

40

45

50

55

60

65

40

0.16
30

35

servations.aErrors
servations.
are in 90%
Errorsconfidence.
are in 90% confidence.
sinθ (light-sec)xax sin θ [light sec.]ax sin θ [lighte sec.]
2

55

(B)

0.24
50 THE
5.4. CORRECTION
5.4. CORRECTION
FOR THE ORBITALFOR
DOPPLERORBITALEFFECTS
DOPPLER EFFECTS

0.2

0.16
30

70

0.34

0.22

0.18

90% Error Size

0.36

Eccentricity

0.38

70

Z2 (m=4)

SuzakuSuzaku, 10—30
keV, m=4Z2 (m=4)

A concern: orbital motion correction

SuzakuSuzaku53.05+0.70
−0.55

+0.70
+0.014
53.05
0.278
−0.55
−0.023τe0+0.0090.278
0.067+0.014−0.023−0.012

40

45

50

55

60

65

40

ax sinθ (light-sec)ω [deg.]τ0PNSω [deg.][s]
Z 2 (m
PNS=[s]4)+0.009+5.1
0.067
54.6+5.1
8.95648(4)
54.6
2
−3.3
−0.012−3.3

8.95648(4)67.97

Z 2 (m67.

FIG. 3. Z statistics considering the orbital motion of LS 5039. The colors indicate the ZMAX values after the orbital correction,+0.4+0.015+0.015+0.0078+2.3+0.0078+2.3
shown on a planeNuSTARof the projectedNuSTAR
orbitalradius of thecompact(a✓, abscissa)
the 9.05381(3)orbital(e, ordinate).66.
48.1+0.4
48.1
0.306
0.306
0.728556.8and56.8eccentricity
9.05381(3)
66.87
X sin
−0.4
−0.4
−0.013star0.7285−0.013−0.0058−3.1−0.0058−3.1
The left and right figures are obtained using the 10–30 keV Suzaku and NuSTAR data respectively.

Thesolutionsfromafter
the
two
data
aresubtraction,
notconsistent.
with Suzaku andwithNuSTAR,
Suzaku and
NuSTAR,backgroundaftersubtraction,
backgroundare
0.68 ± 0.14are
and
0.68
0.135
± 0.14± 0.043,
and 0.135 ± 0.0
A modulationfromthemotion?
Orjustmaynoise?
respectively. different
respectively.
The considerably
The
lower
considerably
pulse orbital
fractionlower pulse
withfraction
NuSTARwith
may
NuSTAR
explainwhytheexplain why
Stay tunedforfuturehardofviaX-ray
observations…
NuSTAR
dataNuSTAR
gave noevidence
data
gaveofno
periodicity
evidence
periodicity
the Fourier
via
analysis,the Fourier
and gaveanalysis,a somewhat
and gave a somew

.1.1
Rotation-powered
pulsarscenario
42 /−1
scenario
possibility
that thethespinneutron
star
5039
is
an
accretingpulsarrejectpossibility
tht
the pulsar
accretingpulsarXcan
Persei,Ṗdefinitively
changes−1.5×we
10−8thats s 54
IfRotation-powered
we measure
period
of in
LSLS
5039
again
and
confirmthat fromṖ theis stable,
which
spins
down.
therotational
peak
is
real,
what
is
EnergySource?
etal., the2018).
we starmeasurethe
spin
oftoLSthe
5039
again
and c
finitively
theIfpossibilitythatneutronin neutron
LSstar5039
is period
anisaccretingpulsarthis scenario,
theenergyofthestar
convertedtotheradiatio
cenario,therotationalenergyloss
ofIflosstheneutronisthe
converted
radiationcanrejectdefinitively
themeasured
possibility
that theneutron
star
in
LS
nergy
the system(Ghosh,2007).
From
the
pulse
period
P
and
its
tim
NS
fown.
the ofsystem(Ghosh,2007).
Fromthemeasured
pulse
period
P
and
its
time
NS
36
How is the luminosity of LS 5039 (10 erg/s) explained?
which
gy
of ofstellar
winds
Kinetic
energystellarerivative
ṖLS
of LS
5039,
the spins
luminosity
L to8.1.3
dueto spin-downoftheneutroNS 5039,e ṖNStheluminosity
Ldown.
spin-downenergyenergy
loss
of loss
the ofneutronsd due sd

·
−10
−1
①
Spin-down
Luminosity
(P
∼
9
s,
P
∼
3
×
10
s
s
)
NS
NS
ar
is
estimatedtobenetic energyof stellar winds
stimated
to betion is somehow hampered, someenergyisEvenstill available
when thewhen
mass accretion is somehow22 (2π)IṖ
NS(2π)=Kinetic
I ṖNS
34
−1
34
−1erg
8.1.3
energyofstellar
winds
L
∼
10
s
,
(8.
sd
L
=
∼
10
erg
s
,
(8.1)
3
sd
ulsar’smagnetosphere.
Assuming
massive
starwinds
launches
the stellar
hitavailable
the pulsar’s
magnetosp
3 thatPthe somehe mass
accretion is somehow
energy
is
still
when
Phampered,NSNS45
2a mass-loss
hhereavelocityatrate
Ṁ,Accretion
thethekinetic
energyof neutron
isotropic
stellarwithastar.
velocityvwene
at45Gravitational
2v
Even
when
the
mass
accretion
is massive
somehow
hampered,
some
w
w
w
I
∼
10
g
cm
ismagnetosphere.
aEnergycanonical
value
of
momentofinertiaoftheneutron
star.
Th
nds
hit
the
pulsar’s
Assuming
that
the
star
launches②
From
Difficult∼ 10 g cm is a canonical
value
of
the
momentof ->inertiaofLwinds
the
This
eract
with
the
pulsar’smagnetosphereis hitcalculated
as thethe stellar
winds
which
interactwiththethatpu
thestellarpulsar’smagnetosphere.
alue
is・P
about
two
of
lower
than
require.
Althoughtheunknown
ar winds
witha orders
velocity
vmagnitude
at lowera winds
mass-lossrate
Ṁ
kinetic
energyLAssumingof equatioisincreasing
・Non-thermal
spectrumaccretingsystemw
w , unlike
w
about
two
ordersof magnitude
thanrequire.
Althoughtheunknown
equation

isotropic
winds
with
aisstarvelocityvπR
a tomass-loss
rate Ṁth
state
for
the
superwithdense
insidea neutron
does
not
allow
us to obtain
nds
which
interactthematter
pulsar’s
calculated
asus
w 2at
w
・No
time-variability
likestellar
accretingsystem
for
the
super
dense
matterinsidea magnetosphereneutronstar 1does
not
allow
obtaintheA
2
Lwinteract∼ Ṁw with
vwCHAPTER
× the pulsar’s
22 at
the
stellarwinds
whichmagnetosphere
8.
DISCUSSION
eciseforvalue
for I,
this uncertainty
canI alter
Ibyonlybya offactorof∼
most(Worleyet a2
4πD
2I, thisalue
uncertainty
can
alter
only
a
factor∼2
atmost(Worley
et
al.,
sep
πR
③
Energyfrom Stellar
Winds
A"Kinetic! (8.2)
"#
#
$
#
$
#
$
×
2
2
−2
008).4πDHence,
is tooforlongforthis object
torotation-powereda rotation-powered
pulsar.
Therefore,th
2 is P
2 be
NSHence,
PNS
too
long
this
objecttobeapulsar.
Therefore,
this
v
R
D
v
Ṁ
1
πR
w
A
sep
w
w
sep
−1
30
1
2 5039 isApowered
erg
s
=
6
×
10
×
ed.−1
Assumingthat "thepulsarinLS
bythemagnetic-fielddissipation
!
L
∼
Ṁ
v
×
w
w$w2 #
(8.2)
#
$
#
$
10
−6
−1
2
enariois
excludedunequivocally.
2−2
yrexcluded
2000
km/s
2
×
10
cm
50
light
sec
10
M
yr
2000 kmis
unequivocally.
2
4πD
"
sep
v
R
D
Ṁ
w
w
A
sep
−1
!
"
e0 samewayasmagnetars,
wecanestimatetheenergyreleaserate Lbf $as2erg
×
s
#
#
$
−6
−1
10
10
M" yr Energy
2000inkm/s
2 × 10star
50 lightvsec
RA
Ṁcm
④
Magnetic
theneutronw
w
30
eparation and RA is the Alfvénradius(seewhere
below).
thatD!sepNoteis thebinary separation and R
=
6
×
10
×
!
"
!
"
"
2
3
−1
2
3
−6 M yr−1
10 cm
.1.2
Accretingpulsarscenario
10
2000
km/s
2
×
10
BNS
Rpulsar
B
Rτ
"
Accretingscenario
NS
NS
NS
37
−1
−6
−1 optical
limit
of
the
mass
loss
rate
of
the
wind
reported
in
an
L
=
∼
10
×
erg
s
, thatof the
(8.3)
10
M
yr
is
the
upper
limit
ma
"
s the bf
binary separation and RA 15
is the Alfvén radius(see below). Note
6τ
10 G
10 km
500 yrere
that
theneutron
star
in LS
5039
istoanaccretingpulsar.
Inscenario,
this
scenari2005).
Again,
thisisofordersofDmagnitude
toolowaccreting
explainthe R(Casareset2005).
Again,
thconsiderthat theneutronstar
inlossLS
5039
isobservationanpulsar.
Inal.,
whereis thebinaryseparationandisthistheAlfvénradiu
is we
the consider
upper
limit
the
mass
rate
of
the
wind
reportedinanoptical
sep
A

15 G
−6
−1fraction
eSCasares
and
B
are
the
radiusandsurfacemagnetic
field
therespectively;eR
neutronstar
gravitationallycapturesafractionofstellar
winds
from
the
massiveThe
neutron
star
in
LS
5039
has
10
magnetic
field?
NSNS
5039.
bolometric
of
LS
5039.
ron
star
gravitationallycapturesaofstellar
winds
from
the
massivestar.
10 Mthisis theofupper
limitluminosity
of of
the
mass
loss
rate
of the staw
et al., 2005). Again,
magnitude
toolow
topulsar,
explainthe" yris orders

43 / 54

A new hypothesis: LS 5039 contains a magnetar?

B ~1014-15 G ➔ Magnetar ?

Magnetars

Moreover,① The period of 9s is similar to magnetars② Strong magnetic field forms the shock
region. Accretion is prevented➔ LS 5039 has no thermal components
Bondi-Hoyle Radius

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⇣
⌘ 2
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3
BNS RNS
Dsep

p

2Ṁw vw!1/3⇠

2 ⇥ 108 ⇥✓BNS
1011 T◆1/3

Tiengo+11

FIGURE 1. Left panel: P − Ṗ diagram for radio puls
RRATs !
(crosses),
XDINs (triangles), AXPs/SGRs (sq
1/6
⇣
⌘ 1/6
Ṁwfrom the ATNF Pulsar vCatalogue([11], http://www.a
w
m,
6
1
1
McGillSGR/AXP
OnlineCatalog(http://www.physics.m
10 M yr2000 km s
indicates the Ṗ upper limit for SGR 0418+5729 [12]. D
109 to 1015 G and characteristic ages from 103 to 10(B/P2 = 1.7 × 1011 G s−2 ,[13]). Middle panel: XMM∼1.5$×3$ field around PSR J2144–3933 in the 0.2–1
the sky region shown in the right panel. Right panel:around PSR J2144–3933. The pulsar proper-motion-cor
corresponding to the image astrometric uncertainty (0.2

③ The magnetar binary hypothesis was proposed for another gamma-

ray binary LS I 61+303, based on magnetar-like X-ray flare (Torres+12)

Strong B fields of the magnetar
explain the MeV emission?
10−9

We proposed two possibilities
for the MeV emission— INFC (0.45 < φ < 0.9)
— SUPC (0.0 < φ < 0.45, 0.9 < φ < 1.0)

10−10ν Fν (erg cm-2 s-1)

44 / 54(1) Synchrotron emission instrong B field, with efficient
acceleration

10−11

10−12

10−13 3
10

104

5

10

6

10

107

8

9

10
10
Energy (eV)

10

10

1011

1012

13

10

1014

(2) Inverse Compton with
GeV electrons

The former scenarios seems to match with themagnetar binary hypothesis→ Efficient acceleration is driven by the magnetar?

45 / 54

An idea: Magnetic Reconnection
The magnetar binary hypothesis + the synchrotron MeV emission scenario
・Energy source is the magnetar’s magnetic energy
・Efficient acceleration (η < 10)

・Very hard injection electron spectrum ( s < 2 )“A direct acceleration powered by magnetic field” seems a good candidate➔ Magnetic Reconnection！
① Anti-parallel magnetic field② Direct acceleration at the X point③ Accelerated particles leave theregion as their trajectories are bent
by the magnetic field➔ hard injection electron & efficient
acceleration (e.g. Zenitani&Hoshino01)
Romanova & Lovelace 1992

46 / 54

But reconnection in binary is possible?
Magnetic reconnection in binaries ???
manuscript submitted to JGR: Space Physics→ A hint: the magnetic field around the Earth（Earth, Solar Wind)(Magnetar, Stellar Wind)

B

A
Earth

Kivelson & Russell 1995

47 / 54

Reconnection around the Earth
NASA video on YouTube

https://www.youtube.com/watch?v=2TnFXddv37E

49 / 54

A Plausible Configuration of Magnetic Field in LS 5039

〜〜〜➤

〜〜〜➤

➤

➤

➤

(A)
➤

➤

➤

➤
➤

➤

➤

➤

〜〜〜➤

〜〜〜➤

➤

➤〜〜〜

Rsh~1.0

➤

〜〜〜➤

R ~
1.5

〜〜〜➤ 〜〜〜➤ lc
light-sec〜〜〜➤ 〜〜
light-sec
〜〜〜➤
〜➤
e-e+
〜〜〜➤

➤

〜〜〜➤

➤
〜➤〜〜
〜〜 〜
〜〜〜➤
〜〜〜
➤

〜〜〜➤

➤

➤

➤〜 ➤
〜
〜
〜 〜〜

〜
➤〜〜➤
〜〜〜

〜〜〜➤

〜➤
〜
〜
〜〜〜➤

➤

UV Photon

Shock(X-ray,Sync.)

➤

〜〜〜➤

- +〜➤
〜〜e
〜➤e
〜〜

〜〜〜➤

Reconnection
Driven Jet (TeV, IC)

➤

〜〜〜➤

〜〜〜➤

➤

〜〜〜➤

〜〜

Stellar Wind

➤〜

〜〜〜➤

➤

magnetic field line

51 / 54

A Plausible Configuration of Magnetic Field in LS 5039

➤
〜
➤〜
➤
Jet Launching
〜
〜
〜
〜
➤
〜
〜
+
〜〜
ee
Point
〜〜 Curvature
➤
➤

(A)

➤

➤〜〜〜

Magnetar

Rrc < 0.4 light-sec

〜
➤
〜
〜
〜
➤〜

✖
✖
✖

➤

Observation
・hard X-ray pulse

➤
〜
〜
〜
〜

➤〜〜〜〜 ➤

Magnetic
Reconnection(MeV, Sync.)➤

Radiation(GeV)➤

magnetic field line

➤

➤

➤

➤

➤

〜
〜
・variability above 10 keV〜〜+
e e 〜〜〜〜〜〜➤
Jet Launching
〜〜
➤
Point
➤

Observation・high-energy
component in
the GeV band・isotropic?

➤

52 / 54

Spectral Model using one-zone model
SUPC

10−9

10−9

10−10

— Shock— Reconnection-Driven Outflow— Magnetic Reconnection
140
10−10
— Curvature Radiation

One zone model considering
synchrotron/IC/adiabaticCHAPTER 8.
losses, assuming several
inferior/superior conjunction (Norm/Normin Table 8.1) reflects thapproximately, but emission
it is still crude. regions
In addition, with
we fixed electron
the scattering anγ-γ absorption range
with the orbital phase.
Future work is needed
to consider
distributionsof Q(γ)∝theseγ-s.effects.
ν Fν (erg cm-2 s-1)

ν Fν (erg cm-2 s-1)

INFC

10−11

10−12

10−11

10−12

−13

10

INFC

−13

3

10

4

10

5

10

6

10

7

10

8

9

10
10
Energy (eV)10

① Direct Acceleration η ∼ 1② Strong B, Synchrotronhν = 236 MeV × η

10

−1

11

10

10

SUPC

Table 8.1: Parameters adopted in Figure 8.2.
Shock Jet Reconnection
Racc (light sec)

5.0

100.0

10−6

B (G)

50.0

0.1

Dacc (light sec)

50.0

100.0

2 × 104

η

10.0

10.0∗

2.5

s

2.4

2.0

1.0

NormINFC /NormSUPC

1.66

4.0

2.0

50.0

13general14
3spectral 4model, it5 is assumed
6812∗ : In thethat 7the emission
and 9acceler

10

10

10
10

10

10

10

10

10
10
1
Energy(eV)in the same region. However, in our scenario the maximum
energyin the jby the reconnection region. Thus, η for the jet spectrum does not mean

efficiency. It is a parameter which determines the maximum energy of electro
the jet. From Equation 7.7, this value corresponds to the maximum energy➔ hard spectrum in the MeV band
8.7

A Plausible Configuration of Magnetic F
in LS 5039

53 / 54

Towards deeper understanding…
・Confirmation of 9 sec hard X-ray pulsation
NuSTAR proposal for additional observation, or to analyze other X-ray data
・Brush up the magnetar binary model・Need for a new MeV gamma-ray observation
Several Compton telescope missions are being prepared! Hope to get new
results of gamma-ray binaries

AMEGO,COSI,

60 DSSD layers!
planed to belaunched in > 2029

Germanium Compton
telescope, SMEX
proposal is selected

GRAMS,
Liquid argon TPC
Compton telescope

SMILE,
Gas TPC Compton
telescope54 / 54

Conclusion
We analyzed the NuSTAR and Fermi 11 years data of LS 5039.
LS 5039 has at least four spectral components from X-rays to TeV
Especially, current models cannot explain the MeV/GeV
components
We also performed the pulse search in hard X-rays for the first time
A sign of 9 sec pulsation is found from both Suzaku and NuSTAR
data, which suggests that LS 5039 contains a magnetar
We propose a new scenario that the compact star in LS 5039 is amagnetar with a strong magnetic field of ∼ 1015 G, and its
magnetic energy is the dominant energy source for non-thermal
activity of LS 5039, through magnetic reconnection.