Rob Fender : Jet-driven cavities around powerful galactic particle accelerators

Speaker : Prof. Rob Fender (University of Oxford) Date : 9th December 2025 Title : Jet-driven cavities around powerful galactic particle accelerators Abstract : Our galaxy is a violent and dynamic environment, in which millions of black holes and neutron stars exist, many thousands in highly active systems called X-ray binaries (aka ‘microquasars’) which dominate the X-ray luminosity of the Milky Way. Known for decades, observations over the past seven years with the MeerKAT radio telescope have revolutionised our understanding of how the powerful jets from these stellar mass black holes carve out parsec-scale cavities in the interstellar medium, transferring vast amounts of energy over twelve orders of magnitude in scale. In parallel, astonishing discoveries by ground-based Cherenkov detectors have revealed the same systems to be luminous sources of very high energy gamma-ray emission, and the new favourite candidates to explain the peta-electronvolt cosmic ray spectrum beyond the ‘knee’ in the cosmic ray spectrum. In this talk I will bring an observational radio astronomer’s perspective to this puzzle and see if these two new strands of discovery can be tied together.