The MeV Properties of the Gamma-Ray Binary LS 5039

Werner Collmar

Max-Planck-Institut für extraterrestrische Physik Garching, Germany

Outline 1) The γ-ray binary LS 5039

2) The COMPTEL source GRO J1823-12 (History)

3) Recent COMPTEL Results on GRO J1823-12/LS 5039

4) Multiwavelength Context and Interpretation

5) Summary

Extreme Astrophysics: June 2014 1 W. Collmar

LS 5039 / RX J1826-1450

AG 2013: Astrophysical Jets 2

LS 5039 (Luminous Stars in the Southern Hemisphere; Stephenson & Sanduleak, 1971)

• LS 5039: variable, X-ray (ROSAT), radio source • relativistic radio jets at milliarcsecs scales (Paredes et al. 2000; Science) -> microquasar -> suggest counterpart of 3EG J1824-1514 -> γ-ray (?) microquasar

• Binary System Parameters (Casares et al. 2005) - O6.5V star: 22.9 (+3.4,-2.9) Msun - Compact object: 3.7(+1.3, -1.0) Msun -> Black Hole Binary (?) - T0 (HJD): 2451943.09

0.10 - Porb: 3.90603

0.00017 d - eccentricity: 0.35

0.04 - f(M): 0.0053

0.0009 - i: 24.9

2.8 deg - distance: 2.5

0.1 kpc

Paredes et al. 2000

Casares et al. 2005

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HESS: Detection of LS 5039 as Gamma-Ray Source (TeV)

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Aharonian et al. 2005

Aharonian et al. 2006

Aharonian et al. 2006

HESS: Detection of LS 5039 as Gamma-Ray Source (TeV)

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Aharonian et al. 2006

Aharonian et al. 2006

Gamma-Ray Binary LS 5039 X-Rays, hard X-rays, medium γ-Rays

SUZAKU (1–60 keV) (Takahashi et al. 2009)

INTEGRAL (25-200 keV) (Hoffmann et al. 2009)

Fermi/LAT (>100 MeV) (Abdo et al. 2009)

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T0 (HJD): 2451943.09

0.10 ; Porb: 3.90603

0.00017 d (Casares et al. 2005)

COMPTEL on CGRO

OSSE (0.05-1 MeV)

COMPTEL (0.75-30 MeV)

EGRET (30-20000 MeV)

BATSE

COMPTEL (Compton Telescope) - energy range: 0.75 – 30 MeV - mounted parallel to EGRET - “first-generation” experiment - pioneered MeV band

BATSE,OSSE COMPTEL EGRET 0.01 0.1 1 10 100 1000 10000 MeV

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3EG J1824-1514

3EG J1812-1316

3EG J1826-1302

3EG J1823-1314 GRO J1817-15

µ-quasar LS 5039

GRO J1823-12 (l/b: 17.5/-0.5) COMPTEL l=18 Source

Ph. I -VI (`91 - `97)

point-source maps: galactic diffuse emission and Crab removed (Collmar et al. 2000)

Summary (Collmar 2003)

• complicated source region • possible counterparts: - 3 known γ-sources (unid. EGRET) - MeV emission: superposition ? - 3EG J1814-1514: microquasar LS 5039(?) • more info needed

Extreme Astrophysics: June 2014 7 W. Collmar

LS 5039: COMPTEL Data Analysis

COMPTEL Data / Analysis • data - data: all within 35º of CGRO pointing (between July 12, 91 – January 25, 2000) - effective exposure: ~81days

• analysis: COMPTEL GRO J1823-12 - inclusion of diffuse emission models (galactic, extragalactic) - inclusion of nearby COMPTEL sources - complete mission in periods of ~ 1 year

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GRO J1823-12 (LS 5039 ?) Orbit-averaged Analysis

1 – 3 MeV 10 - 30 MeV

3 - 10 MeV

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GRO J1823-12 (LS 5039 ?) Orbit-averaged Analysis

• assump.: LS 5039 is GRO J1823-12 • light curve: CGRO phases • spectra: - power-law shapes - 6 years (up to 2nd GRO reboost) - all mission

Extreme Astrophysics: June 2014 10 W. Collmar

GRO J1823-12 (LS 5039 ?) Orbit-averaged Analysis

• assump.: LS 5039 is GRO J1823-12 • light curve: CGRO phases • spectra: - power-law shapes - 6 years (up to 2nd GRO reboost) - all mission

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Error location Contours

GRO J1823-12 (LS 5039) Orbit-resolved Analyses (Ephemeris: Casares et al. 2005)

Superior 0.9 – 0.45

Inferior 0.45 - 0.9

3 – 10 MeV 10 - 30 MeV

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Gamma-Ray Binary LS 5039 Orbit-resolved Analyses

• assumption: all flux from LS 5039 • Spectra for orbital phases: - 0.45 – 0.9; <0.45 & >0.9 - 6 years (up to 2nd GRO reboost) - all mission • lightcurve: orbital phase bin 0.2

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LS 5039 High-Energy Light Curves

at 1 TeV: HESS (Aharonian et al. 2006)

1 – 10 keV: Suzaku (Takahashi et al. 2009)

10 – 30 MeV: COMPTEL (Collmar et al. 2014 )

25 – 200 keV: INTEGRAL (Hoffmann et al. 2009)

> 100 MeV: Fermi/LAT (Abdo et al. 2009)

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LS 5039 High-Energy SED

HESS (Aharonian et al. 2006)

Fermi/LAT (Hadasch et al. 2012)

Suzaku (Takahashi et al. 2009)

COMPTEL (Collmar et al. 2014 )

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Gamma-Ray Binary LS 5039 Modelling

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Black Hole: non-thermal emission powered by accretion and jet ejection

Neutron Star: non-thermal emission powered by interaction between the stellar and pulsar winds (shocked winds?)

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Microquasar LS 5039 Interpretation/Modelling

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Casares et al. (2005)

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Shocked wind IC-Scenario: e+ /e- + pheV -> γMeV Angular dependence of Compton-Scattering Cross Section (?)

Summary/Conclusions • GRO J1823-12: MeV counterpart LS 5039 (at least for rad. majority)

=> LS 5039 is a significant MeV-Emitter

• MeV properties of LS 5039 - steady (non variable?) emitter - emission maximum at MeV energies (high-energy SED) - emission varies by a factor of ~3 along orbit - in orbital phase with X-rays and TeV γ-rays - in orbital antiphase with >100 MeV γ-rays (Fermi/LAT) - „flip back“ occurs between 10 and 100 MeV => provide constraining infos for source modelling

• Modelling - hypotheses: microquasar <-> shocked pulsar wind - correlation X-, MeV γ-, and TeV γ-rays: geometrical origin, e.g. emission at inferior conjunction generally higher (varying Compton Crosssection ?) - simple IC-models do not work

Extreme Astrophysics: June 2014 18 W. Collmar