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HESS upper limits on very high energy gamma-ray emission from the microquasar GRS 1915+105
- Link:
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- Erscheinungsjahr:
- 2009
- Medientyp:
- Text
- Schlagworte:
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- X-rays: binaries
- X-rays: individuals: GRS 1915+105
- gamma rays: observations
- Beschreibung:
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- Context: High energy particles reside in the relativistic jets of microquasars, making them possible sources of very high energy radiation (VHE, <100 GeV). Detecting this emission would provide a new handle on jet physics. Aims: Observations of the microquasar GRS 1915+105 with the HESS telescope array were undertaken in 2004-2008 to search for VHE emission. Methods: Stereoscopic imaging of Cherenkov radiation from extensive air showers is used to reconstruct the energy and direction of the incident gamma rays. Results: There is no evidence for a VHE gamma-ray signal either from the direction of the microquasar or its vicinity. An upper limit of 6.1 × 10-13ph cm-2s-1 (99.9% confidence level) is set on the photon flux above 410 GeV, equivalent to a VHE luminosity of ̃ 1034erg s-1 at 11 kpc. Conclusions. The VHE to X-ray luminosity ratio in GRS 1915+105 is at least four orders of magnitude lower than the ratio observed in gamma-ray binaries. The VHE radiative efficiency of the compact jet is less than 0.01% based on its estimated total power of 10 38 erg s-1. Particle acceleration in GRS 1915+105 is not efficient at high energies and/or the magnetic field is too strong. It is also possible that VHE gamma-rays are produced by GRS 1915+105, but the emission is highly time-dependent. © 2009 ESO.
- Lizenz:
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- info:eu-repo/semantics/openAccess
- Quellsystem:
- Forschungsinformationssystem der UHH
Interne Metadaten
- Quelldatensatz
- oai:www.edit.fis.uni-hamburg.de:publications/e8f75870-5df9-4ab6-bad7-aa0beba5a3bf