X-Ray Binaries as Gamma-Ray Sources

1
X-Ray Binaries as Gamma-Ray Sources
0
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 gt Formation of an
accretion disk
Matter in the accretion disk heats up to 106 K
gt X-ray emission
2
X-Ray Binaries (cont.)
0
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(?)
0
Markoff et al. (2005)
4
g-Ray Emission from Microquasar Jets
0
LS 5039 H.E.S.S. (Aharonian et al. 2005)
5
g-Ray Emission from Microquasar Jets
0
LS I 61o 303 MAGIC (Albert et al. 2006)
? Analogy to blazars!?
6
High-Energy Emission Model for Microquasar Jets
0
Synchrotron emission
Relativistic jet outflow with G 2
Injection, acceleration of ultrarelativistic
electrons
nFn
n
Compton emission
g-q
Qe (g,t)
g
g2
g1
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
0
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
0
MAGIC (gt 400 GeV)
Radio (15 GHz)
Albert et al. (2006)
9
Fit to LSI 61o303
0
Orbital modulation of VHE g-rays can be explained
by gg absorption alone!