1. X-Ray Binaries as Gamma-Ray Sources
Binary systems of a compact object (neutron star or black hole) and a stellar companion
Matter is flowing over from the stellar companion onto the compact object.
Angular momentum conservation
=> Formation of an accretion disk
Matter in the accretion disk heats up to ~ 106 K
=> X-ray emission

2. X-Ray Binaries (cont.)
As in most accretion disk systems, this results in the formation of collimated outflows:
Mildly relativistic jets: G ~ 2
Generally identified as radio jets
X-ray binary spectra typically consist of a thermal disk component plus a hard power-law.

3. X-Ray Emission from Microquasar Jets(?)
Markoff et al. (2005)

4. g-Ray Emission from Microquasar Jets
LS 5039: H.E.S.S. (Aharonian et al. 2005)

5. g-Ray Emission from Microquasar Jets
LS I +61o 303: MAGIC (Albert et al. 2006)
→ Analogy to blazars!?

6. High-Energy Emission Model for Microquasar Jets
Synchrotron emission
Relativistic jet outflow with G ≈ 2
Injection, acceleration of ultrarelativistic electrons
nFn n
Compton emission
g-q
Qe (g,t) g1 g2 g
Leptonic Models
nFn
Injection over finite length near the base of the jet. n
Seed photons:
Synchrotron (SSC), Accr. Disk + BLR (EC)
Additional contribution from gg absorption along the jet
→ Include abs. by companion star light!
+ Companion star light

7. Microquasar Jet Model for LS 5039
Problems with GeV – TeV spectral shape → EGRET (GeV) source may not be associated with LS 5039
Bosch-Ramon et al. (2005)
Böttcher & Dermer (2005)
Dermer & Böttcher (2006)
Gupta et al. (2006)

8. Orbital Modulation in LS I +61 303
MAGIC (> 400 GeV)
Radio (15 GHz)
Albert et al. (2006)

9. Fit to LSI +61o303
Orbital modulation of VHE g-rays can be explained by gg absorption alone!