Summary
Blazars are active galaxies whose central supermassive black holes launch relativistic jets that point almost directly at Earth.
The study found that during periods of lower jet activity, X‑ray emission from the accretion disk around the black hole becomes detectable.
One object, Mrk 421, also displayed a small extra X‑ray feature whose origin is still uncertain.
These observations suggest that blazar X‑ray light can arise from both the jet and the accretion flow, improving our understanding of black‑hole energy processes.