Discovery of Very High Energy Gamma Rays Associated with an X-ray Binary

Abstract

X-ray binaries are composed of a normal star in orbit around a neutron star or stellar-mass black hole. Radio and x-ray observations have led to the presumption that some x-ray binaries called microquasars behave as scaled-down active galactic nuclei. Microquasars have resolved radio emission that is thought to arise from a relativistic outflow akin to active galactic nuclei jets, in which particles can be accelerated to large energies. Very high energy γ-rays produced by the interactions of these particles have been observed from several active galactic nuclei. Using the High Energy Stereoscopic System, we find evidence for gamma-ray emission of >100 gigaelectron volts from a candidate microquasar, LS 5039, showing that particles are also accelerated to very high energies in these systems.

Science 309, 746-749 (2005)
ArXiv pre-print

Auxiliary informations

H.E.S.S. data points for Figure 2

Mean energy    Flux       LowerLimit  UpperLimit
  [TeV]     [/TeV cm^2 s]

0.256        1.835e-11    6.71e-12    3.084e-11
0.4037       1.188e-11    9.384e-12   1.438e-11
0.7293       1.2e-12      6.436e-13   1.755e-12
1.317        6.905e-13    4.807e-13   9.003e-13
2.415        2.667e-13    1.785e-13   3.548e-13
4.441        2.843e-14    6.536e-15   5.794e-14
7.996        < 9.144e-15 (1 sigma)
14.36        < 4.236e-15 (1 sigma)
26.96        < 1.963e-16 (1 sigma)

Remarks: Statistical errors only. Systematic error on energy scale estimated to 20%. See paper for details.

H.E.S.S. sky plot of Figure 1

FITS file

Remarks: The plot is smoothed with instrument’s point spread function. See paper for details.

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