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posted by janrinok on Friday July 29 2016, @07:20AM   Printer-friendly
from the so-much-to-see dept.

Novel observations by an international group of researchers with the CanariCam instrument on the Gran Telescopio CANARIAS provide new information about magnetic fields around the active nucleus of the galaxy Cygnus A. This is the first time that polarimetric observations in the middle infrared region of the spectrum have been made of the nucleus of an active galaxy.

Cygnus A is an elliptical galaxy around 600 million light years from the Earth, which has a supermassive black hole at its centre. It is one of the brightest sources of radio waves in the sky and was featured in Contact, the famous science fiction novel by Carl Sagan, which was made into a film. It has an active galactic nucleus, which means that the black hole is "swallowing" material from its surroundings. When this occurs, strong electromagnetic radiation is produced, as well as large jets of particles, which are emitted from the galactic nucleus at near the speed of light, traveling beyond the edge of the galaxy and reaching three hundred thousand light years into the intergalactic medium.

This is the first time that polarimetric observations in the middle infrared region of the spectrum have been made of the nucleus of an active galaxy. "The combination of the Gran Telescopio CANARIAS (GTC) and CanariCam offers unique capabilities for the observation of active galaxies using polarimetric techniques in the middle infrared," explains Enrique López Rodríguez, a researcher at the University of Texas in Austin (EE UU) and the first author of this study, published in the Astrophysical Journal. "There is no other comparable instrument of this kind," he says. "And no such instruments are expected until the next decade, because the instruments that are being developed now cannot make polarimetric measurements."

Polarimetry is a technique to observe the intensity and the orientation of electromagnetic waves. "If the observed radiation is polarized in a given sense and with a given dependence on wavelength, we can obtain information about the physical mechanisms that produce the polarization. This technique helps us squeeze out the last drop of information from each photon picked up by the GTC," says López Rodríguez.

"Polarimetry," he adds, "lets us eliminate from the observations all the light that is not affected by the magnetic field in the active nucleus, so that we can filter out everything that comes from other sources, such as the galaxy itself, or background stars. This gives us a much higher contrast when we observe the jets and the dust in the galaxy, while studying the influence of the magnetic field on both of them."


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  • (Score: 0) by Anonymous Coward on Friday July 29 2016, @07:31AM

    by Anonymous Coward on Friday July 29 2016, @07:31AM (#381447)

    It's not nice to spy on your grandma like that.