Astrophysique à Haute Energie

Les systèmes binaires X sont des systèmes composés d'un objet compact (un trou noir ou bien une étoile à neutrons) et d'une étoile. Ces systèmes sont "transitoires", c'est-à-dire qu'ils passent la majeure partie de leur temps dans un état dit de "quiescence" où ils sont au repos et très peu brillants.

Recently completed, the Large High Altitude Air Shower Observatory (LHAASO) is the most sensitive detector exploring the sky in the ultra-high-energy (UHE, > 0.1 PeV) gamma-ray domain. It already detected about a dozen sources, whose spectra extend up to photon energies exceeding 1 PeV. Such photons are produced in interactions between protons of multi-PeV energy with ambient matter. These observations are extremely important because, in order to explain the observed spectrum of Galactic cosmic rays, astrophysical sources capable of accelerating protons beyond 1 PeV must exist.

Recently completed, the Large High Altitude Air Shower Observatory (LHAASO) is the most sensitive detector exploring the sky in the ultra-high-energy (UHE, > 0.1 PeV) gamma-ray domain. It already detected about a dozen sources, whose spectra extend up to photon energies exceeding 1 PeV. Such photons are produced in interactions between protons of multi-PeV energy with ambient matter. These observations are extremely important because, in order to explain the observed spectrum of Galactic cosmic rays, astrophysical sources capable of accelerating protons beyond 1 PeV must exist.

Completed in 2021, the Large High Altitude Air Shower Observatory  (LHAASO) is the most sensitive instrument probing the sky in the ultra-high-energy (>0.1 PeV) gamma-ray domain. It already detected about a dozen sources whose spectra extend to PeV energies. Such energetic photons are produced in interactions of multi-PeV cosmic rays with ambient matter. LHAASO sources have been tentatively associated with pulsar wind nebulae, young massive stellar clusters and supernova remnants.

Contexte :
Les étoiles massives vivent en couple…

Super-massive black holes are known to dwell at the center of galaxies. When accreting matter they are observed from Earth as active galactic nuclei (AGNs). In a minority of AGNs the accretion of matter onto the black-hole is associated with the ejection of a relativistic jet of plasma along the polar axis. 
When the black-hole's jet points right in the direction of the Earth, relativistic effects boost the emission and make these objects among the brightest in the Universe. This peculiar AGNs are called blazars.