Why Is There A Star Shortage In The Centers Of Many Galaxies For Decades?

First Posted: Oct 12, 2016 04:41 AM EDT

The astronomers from the Swinburne University of Technology has finally solved the star shortage from the cores of many big galaxies. They investigated two big galaxies and discovered that the principal causes are not the usual ones.

The research, which was printed in the Astrophysical Journal, was led by Dr. Paolo Bonfini from Universidad Nacional Autonoma de Mexico and colleagues . He explained that the smaller of the two galaxies they examined, which is the one with smaller depleted core, likely shaped from the collision of the same galaxies, each seeded with a massive black hole several billion times the mass of the Sun.

Dr. Bonfini said that this well-studied process, the black holes drift towards the center of the newly-formed galaxy by ousting the stars already there, hurling them outward in a gravitational slingshot maneuver. He further said that the pairs of massive black holes effectively work together and hammer each star in a galaxy's core.

A star that comes too close to either black hole can be swallowed. This phenomenon generates high-energy UV and X-ray flares while the star is worn by the immense gravitational field around the black holes. Meanwhile, the black holes emitted a series of gravitational waves, according to Professor Alister Graham, the co-author of the study.

On the other hand, the simulations indicate that if a galaxy collision involves a larger galaxy overriding a smaller satellite galaxy, this could be entirely changed. Professor Ben Moore, the galaxy modeler and director of the University of Zurich's Center for Theoretical Astrophysics and Cosmology in Switzerland explained that the captured galaxies move towards the center of the large galaxy in a braking process that pumps star out of the core of the large galaxy. "Simulations have shown that they do this in such a way that a core of constant stellar density is created, around which the semi-digested satellites then hover."

Prof. Graham said that they suspect that this giant core basically formed from captured satellite galaxies, rather than massive black holes. He further said that that the culprits seem to have quite literally been caught in the act. The research indicates understanding about galaxy cores and the processes that create the evolution of massive galaxies, according to Swinburne Edu.


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