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Ultra-high-energy gamma-ray bubble around microquasar V4641 Sgr
R Alfaro1, C Alvarez2, J C Arteaga-Velázquez3
1Instituto de Física, Universidad Nacional Autónoma de México, Ciudad de México, Mexico.
Nature
|October 16, 2024
Summary
Astronomers detected high-energy gamma-ray emission from the microquasar V4641 Sagittarii, revealing particle acceleration far from its black hole. This discovery suggests microquasar jets may be significant sources of galactic cosmic rays.
Area of Science:
- Astrophysics
- High-energy astrophysics
- Black hole physics
Background:
- Microquasars are binary systems with a black hole and companion star, studied for relativistic particle jets.
- Previous observations of V4641 Sagittarii did not detect gamma-ray emission.
- SS 433, a similar microquasar, shows electron acceleration in its jet far from the black hole.
Purpose of the Study:
- To investigate TeV gamma-ray emission from the microquasar V4641 Sagittarii.
- To understand particle acceleration mechanisms in microquasar jets.
- To assess the contribution of microquasars to galactic cosmic rays.
Main Methods:
- Detection of TeV gamma-ray emission using advanced telescopes.
- Spectral analysis of the gamma-ray emission.
- Comparison of V4641 Sagittarii's emission with other microquasars like SS 433.
Main Results:
- Detection of TeV gamma-ray emission from V4641 Sagittarii.
- Localization of particle acceleration in the jet at distances comparable to SS 433.
- Observation of an exceptionally hard TeV gamma-ray spectrum, extending above 200 TeV.
- The hard spectrum challenges electron acceleration models and suggests potential proton acceleration.
Conclusions:
- V4641 Sagittarii exhibits particle acceleration in its large-scale jets, similar to SS 433.
- The observed gamma-ray spectrum implies either a highly constrained electron acceleration or significant proton acceleration.
- Microquasar jets may be more prevalent sources of galactic cosmic rays than previously thought.
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