Scientists detect ‘gamma heartbeat’ connecting two cosmic forces

Two objects, a cosmic cloud of gas and a supermassive black hole, are simultaneously separated by 100 light years and united by something spectacular – a distinct heartbeat.

An international team of researchers has detected what they describe as a “ gamma heartbeat ” from a cloud of cosmic gas that happens to be synchronized with a massive black hole. They still don’t know exactly how it happened.

The discovery is detailed in a study published Monday in the journal Nature, and provides new clues that may prove useful in improving our understanding of how cosmic rays are produced in the universe.

“Like water in the whirlpool above the drain of a bathtub” – Located about 15,000 light years from Earth in the Milky Way galaxy, a black hole orbits a giant star in a micro-quasar system called SS 433. A quasar is an extremely bright and active galactic nucleus with a supermassive black hole at its center. SS 433 appears as a reduced version of a quasar.

The star is there 30 times more massive than the Sun, and the black hole is about 10 to 20 solar masses.

The two objects orbit each other for a period of 13 days, as the black hole engulfs the material of the giant star.

“This material accumulates in an accretion disk before falling into the black hole, like water in the vortex above a bathtub drain,” explains co-author Jian Li, synchrotron member German electronics (DESY). “However, some of this material does not fall down the drain but spurts out at high speed in two narrow jets in opposite directions above and below the rotating accretion disk.”

The accretion disk is not located precisely in the plane of the star’s orbit and its accompanying black hole, causing it to sway like a spinning top. As a result, the two jets continuously weave their way through space rather than projecting into two straight lines.

The precession, or wobble, of the jets lasts about 162 days. Fascinatingly, about 100 light years from SS 433, astronomers detected a gamma ray signal, or electromagnetic radiation, from a cloud of cosmic gas with the same period of time. This gas cloud is known as Fermi J1913 + 0515.

Scientists believe the black hole is somehow fueling the cloud’s emission of gamma rays because they both follow the same pace – but how and why this is possible has yet to be confirmed.

“Finding such an unambiguous connection by synchronization, about 100 light years from the microquasar, not even in the direction of the jets is as unexpected as it is amazing,” Li said. “But how the black hole can fuel the heartbeat of the cloud of gas is not clear to us. “

More observations are needed to determine the root cause of this unlikely synchronized duo, but scientists so far have a theory: They believe that the nuclei of hydrogen atoms produced at the end of the black hole’s jets cause the ray gamma. emissions.

“The SS 433 continues to amaze observers at all frequencies and theorists,” Li said. “And it is sure to provide a testing ground for our ideas on cosmic ray generation and propagation near microquasars. for the coming years.”

Abstract: Microquasars, local brothers and sisters of extragalactic quasars, are binary systems comprising a compact object and a companion star. By accreting the matter of their companions, microquasars launch powerful winds and jets, influencing the interstellar environment around them. The regular emission of gamma rays is expected to increase from their central objects or from interactions between their outputs and the surrounding environment. This last prediction was recently confirmed with the detection of SS 433 at high energies (TeV)¹. In this report, we analyze more than ten years of gigaelectronvolt gamma ray data from the Fermi Gamma Space Telescope on this source. A detailed examination of the data reveals an emission in the vicinity of SS 433, co-spatial with a gas enhancement, and emission indices possibly associated with an end lobe of one of the jets. The two excess gamma rays are relatively far from the central binary, and the first shows a periodic variation at the precession period of SS 433, connecting it to the microquasar. This result calls into question obvious interpretations and is unexpected from previously published theoretical models. It gives us the opportunity to unveil the transport of particles of SS 433 and to probe the structure of the magnetic field in its vicinity.