Astrophysicists scramble to find answer for mysterious microquasar jets

5 Oct 2018

An artist’s impression showing material ejecting from a region around a supermassive black hole in a quasar. Image: ESO/L Calçada

For the first time, astrophysicists have detected something being emitted from a microquasar – something that doesn’t line up with current theories.

Due to it fundamentally challenging established astrophysics, scientists are truly baffled by the discovery of highly energetic radiation being emitted from a microquasar in deep space.

A microquasar is a black hole that swallows debris from a nearby companion star, blasting it out as enormous jets of material. But this is the first time that such radiation has been detected coming from one.

Publishing their findings in Nature, a team from the US Department of Energy and the Los Alamos National Laboratory strongly suggested that particle collisions at the end of the microquasar’s jets likely produced the powerful gamma rays.

“What’s amazing about this discovery is that all current particle acceleration theories have difficulties explaining the observations,” said Hui Li, a theorist in Los Alamos National Laboratory’s Theoretical Division. “This surely calls for new ideas on particle acceleration in microquasars and black hole systems in general.”

1,000 times more powerful than Large Hadron Collider

Located 15,000 light years away, the microquasar dubbed SS 433 should be incredibly difficult to see from Earth because its jets are pointed away from Earth. Typically, the majority of quasars spotted in deep space have jets pointing directly at Earth, making them easier to see.

However, using the High-Altitude Water Cherenkov Gamma-Ray Observatory (HAWC), the researchers were able to examine data over the course of 1,017 days. This revealed evidence that gamma rays were coming from the ends of the microquasar’s jets, rather than the central part of the star system.

This suggests that electrons in the jets attain energies 1,000 times higher than can be achieved in any particle accelerator here on Earth, such as the Large Hadron Collider.

The jet electrons smash into low-energy microwave background radiation permeating in space, creating the gamma ray emission. This is a newly observed mechanism for getting high-energy gamma rays out of this kind of system and is different from what scientists have observed when the jets are aimed at Earth.

Hao Zhao, also of the research team, added: “The new findings improve our understanding of particle acceleration in jets of microquasars, which also sheds light on jet physics in much larger and more powerful extragalactic jets in quasars.”

Colm Gorey was a senior journalist with Silicon Republic