Study decodes the mysterious life history of supermassive black holes
A new study reports that black holes that emit different optical signatures are in fact living through different stages of the life cycle.
The research, published in The Astrophysical Journal, provides a model for supermassive black holes that all have the same properties.
Previously it was thought that such black holes are the same type of cosmic object viewed from different angles, scientists from Dartmouth College in the United States said, that the results may allow researchers to create more accurate models about the evolution of the universe and shed more light on how the holes evolve black .
Previous studies indicate that supermassive black holes are at the center of almost all large galaxies, including the Milky Way, consuming galactic gas, dust, and stars, sometimes becoming heavier than smaller galaxies.
Scientists noted that when dusty material falls into these black holes at incredible speeds, they light up and emit radiation at wavelengths of infrared or X-rays that outlast the entire host galaxy.
Astronomers refer to active supermassive black holes at the center of their host galaxy that grow by accretion of matter as active galactic nuclei (AGNs).
“These objects have puzzled researchers for more than half a century, and over time we have made many assumptions about the physics of these objects,” said lead study author Tonima Tasnim Inanna, a postdoctoral researcher at Dartmouth College. Active galactic nuclei are not so hidden.”
Scientists have been studying AGNs for decades by evaluating their optical signatures, and since the 1980s, by analyzing X-ray wavelength signals, they hypothesized that AGNs typically contain a ring-shaped cake, or "hoop" of gas and dust around them.
The researchers believe that the different brightness and colors associated with the objects are due to the angle at which the active galactic nuclei are observed and the amount of torus obscuring the view.
Based on this belief, the scientists said, the unified AGN theory became the dominant concept.
In the new study, researchers assessed how quickly black holes feed on space matter or their accretion rates, and found that the rate of accumulation does not depend on the mass of the black hole, but varies greatly depending on how much it is obscured by the gas and dust ring.
This supports the idea that the ring structures around black holes are not all the same, and Ryan Hickox, a professor of physics and astronomy and one of the study's authors, explained that there is a relationship between the structure and how it grows.
The new research indicates that the amount of dust surrounding the AGN is directly related to the amount of nutrition, indicating that there are differences beyond the trend between different groups of AGN.
Scientists said that the accretion black hole is actively removing dust and gas, and is likely to appear brighter, while a less active active core surrounds a denser ring and appears fainter.
“In the past, it was uncertain how a group of obscured AGNs differed from their more easily observable and unobstructed counterparts,” said Dr. Inanna. “This new research conclusively demonstrates a fundamental difference between the two groups that goes beyond the viewing angle.”
By knowing the mass of the black hole and the extent of its feeding activity, scientists can determine when the majority of supermassive black holes underwent most of their growth.
The researchers believe that the latest findings solve an important part of the puzzle of “where supermassive black holes come from” and provide valuable information about the evolution of these cosmic entities and the universe.
Source: independent
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