A Mysterious Black Hole With Misaligned Accretion disk

  • Researchers shed light on a mysterious black hole located 8,000 light-years away from Earth. 
  • Typically, jets are ejected straight out from the poles of black holes, perpendicular to the material disc.
  • This one is a unique case because the black hole and the disc of material are misaligned. 

In astrophysics, accretion disks are a ubiquitous phenomenon: protoplanetary disks, active galactic nuclei, and gamma-ray bursts all involve accretion disks. These disks are known for giving rise to astrophysical jets coming from the central object’s vicinity.

Accreting black holes provide kinetic feedback to their surroundings through powerful relativistic jets. Jets redirected by or originated from the accretion flow that powers them are affected by the dynamics of the flow.

Typically, these jets are ejected straight out from the poles of black holes, perpendicular to the material disc that is accreted from the companion star. Until now, astronomers had observed only one black hole with a rotating jet. However, its rotational speed was much slower, completing one cycle every half a year.

Recently, researchers have shed light on a mysterious black hole that is ejecting powerful plasma jets while rotating through space. The calculations show that the black hole and disc of material are misaligned.

The Inner Workings Of The Cosmic Monster

The black hole is located about 8,000 light-years away and is a part of V404 Cygni, a binary system in the constellation of Cygnus. Astronomers were able to detect this black in 1989 when it ejected massive matter and high-energy radiation.

In 2015, the black hole became active again for a few days and the European Space Agency’s INTEGRAL high-energy observatory captured this moment. In fact, several space- and ground-based telescopes pointed towards this black hole and found its odd behavior.

Researchers analyzed that data captured during the outburst and found that the jets were ejecting in several directions on an hour timescale. This indicates that the system’s inner regions were rotating faster.

Reference: Nature | DOI:10.1038/s41586-019-1152-0 | ESA 

The data from numerous space observatories, including INTEGRAL high-energy X-ray, allowed researchers to find out what exactly was going on inside the inner section of 6.2 million mile-wide accretion disc.

As per the report, the black hole and the material disc are misaligned. The inner section of the disc wobbles like a spinning top which is slowing down, and jets shoot out in various directions as it alters orientation.

Black hole with inclined accretion disc | Credit: ICRAR

A massive amount of material fell into the black hole during the outburst, which temporarily increased the accretion rate of disc material, dramatically surging the energy.

The observations made by INTEGRAL were used to determine the accretion geometry and energy. This is important to understand the connection between incoming and outflowing matter to build a whole image of the scenario.

What Caused This Unusual Misalignment?

Since the spin of the black hole is inclined towards the companion star’s orbit, the inner section of the accretion disc is inclined with respect to the rest of the system. This misalignment might have been caused by a supernova explosion, which ‘kicked’ the black hole and forced it to spin on a tilted axis.

Read: Is It Possible To Measure The Mass Of Supermassive Black Hole?

The calculations fit in this scenario, as well as in modern simulations that show that the accretion flow and jets can rotate together. According to the researchers, similar dynamics can be expected in almost all highly accreting black hole whose spin isn’t perfectly aligned with the incoming matter. Also, it’s crucial to take inclination angles [of varying jets] into account while studying far distant black holes in the Universe.

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