• Scientists detected a cosmic "heartbeat" in the Milky Way
  • A microquasar and a gas cloud are pulsing in sync despite being far from each other
  • Exactly how the two are connected remains a mystery

Scientists detected a gas cloud that is beating to the rhythm of a neighboring black hole. Exactly how the black hole powers the cosmic "heartbeat" remains a mystery.

Microquasars are binary systems that are composed of a compact object and a companion star from where it accretes material. When they do, microquasars shoot out powerful jets and form a disk of hot gas around the compact object.

SS 433 is a microquasar 15,000 light years away in the Milky Way and scientists believe it consists most likely of a black hole about 10 to 20 solar masses and a companion giant star. They orbit each other every 13 days, during which the black hole accretes material from its companion.

Using over a decade of data from NASA's Fermi Gamma-ray Space Telescope, an international team of scientists detected something odd in the vicinity of SS 433. About 100 light years away, a gas cloud is "beating" to the same rhythm as SS433, which pulses once every 162 days.

In an animation of the cosmic heartbeat, one can see how SS 433 and the gas cloud dubbed Fermi J1913+0515 are pulsing in exactly the same rhythm, suggesting that Fermi J1913+051 5 is being powered by SS 433 despite being vastly distant from each other.

"The timing signal we found provides an unambiguous connection between the microquasar and the cloud, separated by about 100 light years," one of the study leads, Professor Diego F. Torres of the Institute of Space Sciences, said in a news release from the institute. "This is as amazing as is intriguing, opening questions regarding how the black hole powers the cloud's heartbeat thus far."

However, models suggest the gamma ray heartbeat should be too far to be connected to SS 443 as the jet structure would collapse before they even reach 100 light years. Further, the gas cloud is not even along the jets' direction, so it is unlikely it is being illuminated by the jets.

Another possibility is that the team looked at is that fast protons at the end of the jets or perhaps close to the black hole may be injected into the cloud, thereby producing the synchronized gamma-ray heartbeat.

That said, the researchers are still unsure as to how exactly SS 433 is powering Fermi J1913+0515.

"This result challenges obvious interpretations and is unexpected from previously published theoretical models," the researchers wrote.

As such, further studies are needed to unveil the mechanisms that connect the two.

"SS 433 continues to amaze observers at all frequencies and theoreticians alike," another study lead, Jian Li of Deutsches Elektronen-Synchrotron (DESY), said in a news release from the research center. "And it is certain to provide a testbed for our ideas on cosmic-ray production and propagation near micro quasars for years to come."

The study is published in the journal Nature Astronomy.

Cosmic Heartbeat
Image: Illustration of microquasar SS 433 (background) and gas cloud J1913+0515 (foreground). DESY, Science Communication Lab