Astronomers find quasars are not nailed to the sky

phys.org | 3/14/2019 | Staff
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Until recently, quasars were thought to have essentially fixed positions in the sky. While near-Earth objects move along complex trajectories, quasars are so remote that they were believed to offer stable and reliable reference points for use in navigation and plate tectonics research. Now, an international team of astrophysicists featuring researchers from the Moscow Institute of Physics and Technology has found that quasars are not entirely motionless and explained this behavior. The findings were published in the Monthly Notices of the Royal Astronomical Society.

"The apparent positions of quasars change with the radiation frequency used to observe them. Researchers predicted this effect about 40 years ago based on the theory of synchrotron radiation and observed it soon afterwards," explains Alexander Pushkarev, a leading researcher at the Crimean Astrophysical Observatory and Lebedev Physical Institute of the Russian Academy of Sciences. "Our study aimed to find whether this effect varies with time, and if so, then on what timescales and to what extent the apparent position shift changes."

Quasars - Class - Objects - Nuclei - None

Quasars belong to a broader class of astronomical objects known as active galactic nuclei. Fortunately, none of them are located close to Earth. An AGN is basically a "fire-breathing" black hole incinerating its surroundings with two oppositely directed jets of plasma moving at relativistic speeds. Lurking at the heart of an AGN, the black hole itself is, naturally, invisible. This central object is shrouded with a region penetrable only to the highest-frequency radiation. As a result, an Earth-based observer sees an AGN differently depending on the radiation frequency used. For example, while optical observations reveal the jet and the glow around its source, radio telescopes can only discern the part of the quasar "tail" directed at us.

The most precise currently available technique for radio observation of remote objects is known as very long baseline interferometry. It...
(Excerpt) Read more at: phys.org
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