LONDON – An international team of astronomers, in a study published Wednesday in Nature magazine, is proposing a new model to explain the formation of supermassive black holes in the center of so-called “jellyfish” galaxies, huge spiral structures in deep space with arms that resemble tentacles.
The study, headed by scientists at the INAF Astronomical Observatory in Padua, Italy, studied images obtained by the VLT telescope at the Paranal observatory in Chile.
The astronomers analyzed the configurations of seven jellyfish galaxies located in galaxy clusters relatively close to Earth, six of which contain supermassive black holes at their centers that “feed” on gas circling around and into them due to their huge gravity.
The proportion of supermassive black holes found in such galaxies is far above the normal level, with just one in 10 “regular” galaxies having black holes with those characteristics.
The “solid link” between the two phenomena had not been predicted or discovered before, researcher Bianca Poggianti said in a communique from INAF.
The statistically significant find prompted researchers to analyze the formation process for jellyfish galaxies, the structure of which is the result of ram-pressure processes similar to those created in fluids.
The galaxies are attracted toward the centers of the clusters due to gravity.
During their “fall” toward a cluster’s center, the galaxies pass through regions of dense and hot gases that act on them like a strong wind that blows off long tails of gas toward the exterior of the main disk.
It seems that the central black hole can feed on part of the gas because, instead of being lost, it moves toward the center of the galaxy, Poggianti said.
The model proposed by the researcher and her group deals with the question of why just a small fraction of supermassive black holes in the center of galaxies are active, a phenomenon that is as yet unexplained by astronomers.
Yara Jaffe, with the European Southern Observatory, said that the recent observations suggest a new mechanism whereby the gas is channeled toward the black hole.
The result is important, she said, because it contributes a new piece to the puzzle connecting black holes with the galaxies housing them, a mechanism that is still not fully understood.