Scientists may have found evidence that vampire black holes feeding on their victim stars — so-called microquasars — are the cosmic particle accelerators that are responsible for mysterious high-energy cosmic rays we see bombarding Earth. Here are more details about this.
Vampire black holes
Stellar mass black holes are found in binary systems with a supergiant star. These black holes strip material from their companion star and channel some of it to their poles. At the poles, the material is then released in high-speed relativistic jets.
These black holes are called microquasars and they are similar to quasars, which are powered by giant supermassive black holes. However, microquasars are not as extreme as quasars.
Cosmic rays were first discovered in 1912 and they can hit our planet with energies reaching 10²⁰ electronvolts (eV). This is more energetic than the particles accelerated at the Large Hardon Collider, which is Earth’s largest and most powerful particle accelerator.
Supernovas and microquasars have been suggested as the universe’s powerful cosmic particle accelerators.
Scientists believe that these phenomena could be responsible for the high-energy cosmic rays recorded on our planet. However, evidence of microquasars accelerating particles to such high energies has been scarce — until now.
The team discovered the link between cosmic rays and microquasars while using the High Energy Stereoscopic System (H.E.S.S.).
They detected extremely high-energy gamma rays emanating from the jets of the Milky Way’s most potent microquasar, SS 433.
These gamma rays are created when the jets of SS 433 collide with the surrounding matter, causing a shock front that accelerates electrons to speeds great enough to account for the particles seen in high-energy cosmic rays.
“The acceleration mechanism would be similar to that in a supernova remnant, although the shocks in SS 433 jets are faster than supernova remnant shocks and can accelerate particles to higher energies,” Valentí Bosch-Ramon, an associate professor at the University of Barcelona, wrote in a perspectives paper discussing the research published in Science.
“The very energetic photons detected from the large-scale jets of SS 433 are an indirect indicator that these kinds of objects should not be neglected when seeking to explain the most energetic nuclei in Galactic cosmic rays.”