Transcript LS 5039**** GeV

(Yamaguchi & Takahara 2012, submitted)
大阪大学 山口正輝
共同研究者： 高原文郎
GCOE研究集会「Multi-Messenger Astronomyで迫るコンパクト天体」
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Gamma-ray binary, LS5039
GeV break problem
Model with a soft X-ray source
Summary
• Gamma-rays vary with orbital period
Objects
Period
Scale
LS 5039
3.9d
5x10^12cm O + ?? (BH or NS)
LS I +61° 303
26d
10^13cm
Be + ??
PSR B1259-63
3.4yr
10^14cm
Be + NS
HESS J0632+057
320d
10^14cm
Be + ??
10^13cm
O + ??
1FGL J1018.6-5856 16d
Consists of …
• Gamma-rays are detected as flares
Cyg X-1
5.6d
3x10^12cm O + BH
Cyg X-3
4.8hr
5x10^11cm WR + ??(BH or NS)
 Candidate:
AGL J2241+4454 (HD 215227(Be))
superior inferior
F. Aharonian, et al., 2006, A&A, 460, 743
A. A. Abdo, et al., 2009, ApJL, 706, 56
T. Takahashi, et al., 2009, ApJ, 697, 592
Fermi
HESS
INFC
SUPC
Suzaku
HESS
SUPC
Fermi
MS
INFC
Suzaku
Photon energy (eV)
Phase-averaged spectra
Orbital phase
Light curves
・TeV & GeV anticorrelate
・TeV & X correlate
・spectral break at ~1 GeV

If electrons scatter off stellar photons, the break
is not reproduced
 Assume that the break is due to γγ absorption
 Typical energy of absorbed photons: tens of GeV
2
Eabs ~ ( Ee,rest mass ) E ~ 30 GeV
If 10 times of this
Yamaguchi & Takahara, 2010, ApJ, 717, 85
3G
Eabs ~ 3 GeV
Therefore,
 We assume that electrons
scatter off 100 eV photons
0.1G
Requirement for 100eV source
 Optical depth τ > 1
R100eV  108 cm
 No influence on Suzaku data
R100eV  108 cm
γ-ray
injection site
Electron injection
8
10
cm
 Energy of e± < 1TeV
 near 100 eV source
100eV source
 Magnetic field: a parameter

we calculate cascade with 100eV photons,
and with stellar photons far from it
i  30 , 1 GeV  Ee, inj  50 TeV(index : 2.5)

B = 100 G



B = 300 G

GeV break is reproduced
X-ray spectral index
matches when B=100G
X-ray flux matches
when B=300G
No orbital variation in
X-ray and GeV band
Strong magnetic field
 Uph (100 eV) > Uph(stellar photon)
→ IC cooling time shorter
→ the number of e± smaller
→ strong B is required to fit with obs.
Superior conjunction
No variation in GeV & X-ray band
 e± scatter off photons near CS
O star
CS
→ direction to CS independent of phase Inferior conjunction
→ No modulation in GeV band
 No change in the number of electrons
→ No modulation in X-ray band
O star
CS
For LS 5039, the observed break energy in GeV band
is 3 GeV, different from expected one
 So we introduce 100eV photon source
 spectral break is reproduced
 X-ray flux is reproduced when B = 300 G
 X-ray & GeV have no variation (by isotropy of 100eV
source)
 This is a possible model!
prospect
 With 100eV source, we introduce orbital variation of
injection (as in Owocki et al. 2010, proceeding)
 Without 100eV source, we regard GeV cutoff as high
energy cutoff of injected e±
