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LHAASO Links Cosmic-Ray 'Knee' to Black Hole Micro-Quasars

Detections from five systems reveal PeV acceleration that defines a distinct high-energy proton component.

Overview

  • The observatory reported ultra-high-energy gamma rays from SS 433, V4641 Sgr, GRS 1915+105, MAXI J1820+070, and Cygnus X-1.
  • In SS 433, emission overlapping a giant atomic cloud indicates black-hole-accelerated protons above 1 PeV with a power near 10^32 joules per second.
  • V4641 Sgr produced gamma rays up to 0.8 PeV, implying parent particles exceeding 10 PeV and identifying it as a super-PeV accelerator.
  • Using multi-parameter selection, LHAASO isolated a high-purity proton sample and measured a spectrum that reveals an unexpected high-energy component near the knee.
  • Synthesizing these results with AMS-02 and DAMPE data points to multiple Galactic accelerator classes, with the knee marking the energy limit of sources powered by black hole jets.