On the nature of the episodic gamma-ray flare observed in Cygnus X-1
The high-mass microquasar Cygnus X-1, the best established candidate for a stellar-mass black hole, has been detected in a flaring state at very high energies, E > 200 GeV (Albert et al. 2007). The observation was per- formed by the Atmospheric Cherenkov Telescope MAGIC. It is the first experimen...
| Autores: | , , |
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| Formato: | artículo |
| Estado: | Versión publicada |
| Fecha de publicación: | 2009 |
| País: | Argentina |
| Recursos: | Universidad Nacional de La Plata |
| Repositorio: | SEDICI (UNLP) |
| Idioma: | inglés |
| OAI Identifier: | oai:sedici.unlp.edu.ar:10915/99098 |
| Acesso em linha: | http://sedici.unlp.edu.ar/handle/10915/99098 |
| Access Level: | acceso abierto |
| Palavra-chave: | Física Ciencias Astronómicas X ray binaries Gamma rays Microquásars Cygnus X-1 (microcuásar) |
| Resumo: | The high-mass microquasar Cygnus X-1, the best established candidate for a stellar-mass black hole, has been detected in a flaring state at very high energies, E > 200 GeV (Albert et al. 2007). The observation was per- formed by the Atmospheric Cherenkov Telescope MAGIC. It is the first experimental evidence of very high energy emission produced by a galactic stellar-mass black hole. The observed high energy excess occurred in coin- cidence with an X-ray flare. The flare took place at orbital phase = 0.91, being = 1 the moment when the black hole is behind the companion star. In this configuration the absorption of gamma-ray photons produced by photon-photon annihilation with the stellar field is expected to be the highest. We present detailed calculations of the gamma-ray opacity due to pair creation along the whole orbit, and for different locations of the emitter (height above the compact object). We discuss the location of the gamma- ray producing region in Cygnus X-1 and the energetics required to produce the flare. |
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