UMCP: Black Holes with Ravenous Appetites Define Type I Active Galaxies

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UMCP: Black Holes with Ravenous Appetites Define Type I Active Galaxies

Post by bystander » Thu Sep 28, 2017 12:06 am

Black Holes with Ravenous Appetites Define Type I Active Galaxies
University of Maryland, College Park | CMNS | 2017 Sep 27

New research suggests that the central black holes in Type I and Type II active galaxies consume matter at different rates, upending popular theory
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For decades, astronomers have tried to pin down why two of the most common types of active galaxies, known as Type I and Type II galaxies, appear different when observed from Earth. Although both galaxy types host voracious supermassive black holes known as active galactic nuclei, which actively swallow matter and emit massive amounts of radiation, Type I galaxies appear brighter to astronomers’ telescopes.

New research from an international team of astronomers, with contributions from the University of Maryland, makes a major modification to a popular theory called the unified model. According to this model, the active nuclei of Type I and Type II galaxies have the same fundamental structure and energetic profile, but appear different solely because the galaxies point toward Earth at different angles. Specifically, Type II galaxies are tilted such that they are obscured by their own rings of dust, making Type I galaxies appear brighter by comparison.

The new results, published September 28, 2017, in the journal Nature, suggest that Type I and Type II galaxies do not just appear different—they are, in fact, very different from each other, both structurally and energetically. The key factor that distinguishes Type I and Type II galaxies is the rate at which their central black holes consume matter and spit out energy, according to the researchers. ...

The Close Environments of Accreting Massive Black Holes Are Shaped by Radiative Feedback - Claudio Ricci et al
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Many active galactic nuclei are surrounded by large, dark, donut-shaped <br />clouds of gas and dust, as seen in this artist’s rendering. A popular theory <br />known as the “unified theory” suggests that differences in the brightness of <br />active galactic nuclei, as seen from here on Earth, are due to the placement <br />of this donut of obscuring dust relative to our angle of observation. However, <br />new research suggests that two of the most common types of active galactic <br />nuclei do, in fact, exhibit fundamental physical differences in the way they <br />consume matter and spit out energy. Credit: NASA/JPL-Caltech
Many active galactic nuclei are surrounded by large, dark, donut-shaped
clouds of gas and dust, as seen in this artist’s rendering. A popular theory
known as the “unified theory” suggests that differences in the brightness of
active galactic nuclei, as seen from here on Earth, are due to the placement
of this donut of obscuring dust relative to our angle of observation. However,
new research suggests that two of the most common types of active galactic
nuclei do, in fact, exhibit fundamental physical differences in the way they
consume matter and spit out energy. Credit: NASA/JPL-Caltech
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