(ORDO NEWS) — Since 2015, the LIGO-Virgo-KAGRA collaboration has detected about 85 pairs of black holes colliding with each other.
These cosmic catastrophes are known to occur frequently: as the sensitivity of the detector increases, scientists expect that in the next cycle of observations, starting in 2023, they will receive data on these events almost daily.
However, scientists do not yet know what causes these collisions.
One way to force black holes to merge is to collide them in densely populated environments, such as the centers of star clusters.
In stellar clusters, black holes that are very far apart can converge as a result of two factors – mass segregation and dynamical interactions.
Mass segregation causes the most massive objects to sink towards the middle of the gravitational potential well.
This means that any black holes scattered throughout the cluster should end up in the middle, forming an invisible “dark core”.
Dynamic interactions are the second mechanism that influences the approach of black holes.
If two black holes cluster together, their interaction can be affected by the gravitational influence of nearby objects.
This impact can bring the binary system closer together.
Mass segregation and dynamic interactions that can occur in star clusters leave their mark on the properties of merging binary systems.
One of the key properties is the shape of the binary system’s orbit just before its merger. Since mergers in star clusters can occur very quickly, orbital shapes can be quite elongated, similar to a flattened ellipse.
A team of OzGrav researchers and alumni are working together to study the orbits of binary black holes.
A team led by Dr. Isobel Romero-Shaw, along with Professors Paul Lasky and Eric Train of Monash University, found that some of the binary systems observed by LIGO-Virgo-KAGRA do indeed have elongated orbits, indicating that they may have collided. in a densely populated star cluster.
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