Another way for stellar-mass black holes to grow larger

How can some stellar-mass black holes grow bigger than others?

This artist's impression shows a binary system containing a stellar-mass black hole called IGR J17091-3624, or IGR J17091 for short. The strong gravity of the black hole, on the left, is pulling gas away from a companion star on the right. This gas forms a disk of hot gas around the black hole, and the wind is driven off this disk. Credit: NASA/CXC/M.Weiss
This artist's impression shows a binary system containing a stellar-mass black hole called IGR J17091-3624, or IGR J17091 for short. The strong gravity of the black hole, on the left, is pulling gas away from a companion star on the right. This gas forms a disk of hot gas around the black hole, and the wind is driven off this disk. Credit: NASA/CXC/M.Weiss

Scientists at the University of Hong Kong and Academia Sinica Institute of Astronomy and Astrophysics in Taiwan and Northwestern University in the U.S. come in collaboration and establish a new hypothesis where they explained how some stellar-mass black holes can grow bigger than others.

Since the underlying discovery of gravitational waves three years prior, five more detections have been observed—and five of the aggregate have been followed back to outflows made by two stellar-mass black holes merging. The 6th was attributed to neutron stars consolidating.

As a major aspect of their investigations of such detections, space analysts have been amazed by the size of the stellar-mass black holes creating the gravity waves—they were greater than other stellar-mass black holes. Their bigger size has up to this point been clarified by the hypothesis that they became bigger because they started their lives as stars that contained small amounts of metal—stars with traces of metals would hold the majority of their mass since they deliver weaker solar wind.

In this new effort, the specialists propose another conceivable way for stellar-mass black holes to grow larger than typical. They started by noting some supermassive black holes at the hearts of galaxies are surrounded by a disk of gas and dust.

In such systems, there are frequent stars lying simply outside the disk—stars that could develop to wind up stellar-mass dark openings. The specialists propose that it is conceivable that sometimes, sets of these stars end up in the plate as they evolve into black holes. Such stellar-mass black holes would pull in material from the disk, making them grow larger.

Scientists noted, if such a scenario were to play out, it is also possible that the two merging stars could wind up with a synchronized spin resulting in a stellar-mass black hole that produces more gravity waves than if the spins had not been synchronized, making them easier for researchers to spot.

Scientists have published their paper published in The Astrophysical Journal Letters.