GX 339−4
Variable galactic LMXB black hole candidate with relativistic jet.
GX 339−4 is a galactic low-mass X-ray binary and black hole candidate that varies in brightness and undergoes occasional flares. Spectroscopic measurements indicate its black hole has a mass of at least 5.8 times that of the Sun. Discovered in 1973 by Thomas Henry Markert and his team using data from the MIT Cosmic Ray Experiment on the OSO-7 satellite, its optical counterpart was identified by Jonathan E. Grindlay in 1979. Because this optical source is also variable, it received the variable star designation V821 Arae in 1981. During outbursts, the system shows quasi-periodic oscillations whose frequency rises as the CENBOL region moves closer to the black hole and falls as it recedes when viscosity decreases, matching a model of a propagating and oscillating shock in sub-Keplerian flow. The overall spectrum is well described by a two-component advective flow solution. A strong, variable relativistic jet has been observed across radio to infrared wavelengths.
- Discovery year
- 1973
- Discoverer
- Thomas Henry Markert et al.
- Optical counterpart discoverer
- Jonathan E. Grindlay
- Optical counterpart discovery year
- 1979
- Variable star designation
- V821 Arae
- Variable star designation year
- 1981
- Minimum black hole mass
- 5.8 solar masses
Lore & Background
GX 339−4 was discovered in 1973 by Thomas Henry Markert et al., using data from the MIT Cosmic Ray Experiment on OSO-7. An optical counterpart to the X-ray source was found by Jonathan E. Grindlay in 1979, and because it is optically variable, it received the variable star designation V821 Arae in 1981. Spectroscopic measurements have determined the mass of the black hole to be at least 5.8 solar masses.
During outbursts, GX 339−4 shows evolution of quasi-periodic oscillations (QPOs). In the rising phase, the QPO frequency monotonically increases as the CENBOL propagates closer to the black hole; in the declining phase, the frequency monotonically decreases as the CENBOL recedes after viscosity decreases. This frequency variation is well modeled by a propagating and oscillating shock in the sub-Keplerian flow, and the entire spectrum fits well using a two-component advective flow solution.
A strong, variable relativistic jet, emitting from radio to infrared wavelengths, has been observed by several studies.
Reader's Guide
GX 339−4 holds significance as a well-studied black hole candidate in a low-mass X-ray binary system, with its minimum mass firmly established at 5.8 solar masses. Its optical variability led to its designation as V821 Arae, linking X-ray and optical astronomy. The system's outbursts provide a natural laboratory for studying quasi-periodic oscillations and the behavior of accretion flows around black holes. The observed monotonic frequency changes in QPOs during rising and declining phases support models involving a propagating shock in sub-Keplerian flow, specifically the CENBOL region. Additionally, the detection of a strong, variable relativistic jet across radio to infrared wavelengths underscores the system's energetic processes and its role in understanding jet formation in accreting black holes. The two-component advective flow solution that fits the entire spectrum further enhances its legacy as a key object for testing accretion and jet theories in galactic black hole candidates.
Did You Know?
- Its optical counterpart was found by Jonathan E. Grindlay in 1979, leading to the variable star designation V821 Arae in 1981.
- The black hole in GX 339−4 has a minimum mass of 5.8 solar masses.
- During outbursts, the quasi-periodic oscillation frequency increases in the rising phase and decreases in the declining phase.
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