EHT Pinpoints Dark Heart of the Nearest Radio Galaxy

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EHT Pinpoints Dark Heart of the Nearest Radio Galaxy

Post by bystander » Mon Jul 19, 2021 6:32 pm

EHT Pinpoints Dark Heart of the Nearest Radio Galaxy
Event Horizon Telescope | ALMA (ESO/NAOJ/NRAO) | 2021 Jul 19

Into the Dark Heart of Centaurus A
Max Planck Institute for Radio Astronomy (MPIfR) | 2021 Jul 16

An international team anchored by the Event Horizon Telescope (EHT) Collaboration known for capturing the first image of a black hole in the galaxy M87 has now imaged the heart of the nearby radio galaxy Centaurus A in unprecedented detail. The astronomers pinpoint the location of the central supermassive black hole and reveal how a gigantic jet is being born. Most remarkably, only the outer edges of the jet seem to emit radiation. This is challenging theoretical models of jets. ...

Highest resolution image of the Centaurus A jet obtained with the Event
Horizon Telescope on top of a color composite image of the entire galaxy.
Credit: Radboud University; ESO/WFI; MPIfR/ESO/APEX/A. Weiss et al.;
NASA/CXC/CfA/R. Kraft et al.; EHT/M. Janssen et al.

At radio wavelengths, Centaurus A emerges as one of the largest and brightest objects in the night sky. After it was identified as one of the first known extragalactic radio sources in 1949 (with the galaxy NGC 5128), Centaurus A has been studied extensively across the entire electromagnetic spectrum by a variety of radio, infrared, optical, X-ray, and gamma-ray observatories. At the center of Centaurus A lies a black hole with the mass of 55 million suns, which is right between the mass scales of the M87 black hole (six and a half billion suns) and the one in the center of our own galaxy (about four million suns).

In a new paper in Nature Astronomy, data from the 2017 EHT observations have been analyzed to image Centaurus A in unprecedented detail. "This allows us for the first time to see and study an extragalactic radio jet on scales smaller than the distance light travels in one day. We see up close and personally how a monstrously gigantic jet launched by a supermassive black hole is being born”, says astronomer Michael Janssen.

Centaurus A was probed at 1-mm wavelength by record-breaking observations with a single pair of telescopes in January 2015, as it was observed by the APEX telescope and the radio telescope at the South Pole (SPT). “These pioneering observations, from which we could only estimate the compactness of the heart of the source, paved the way to the image we present now, once the full EHT array has been deployed”, adds astronomer Eduardo Ros from the Max Planck Institute for Radio Astronomy (MPIfR).

Compared to all previous high-resolution observations, the jet launched in Centaurus A is imaged at a tenfold higher frequency and sixteen times sharper resolution. With the resolving power of the EHT, we can now connect the vast dimensions of Centaurus A. The large-scale radio source shows an extent as big as 16 times the angular diameter of the Moon on the sky. The origin of the jet near the black hole occurs in a region of merely the width of an apple on the Moon when projected on the sky. That corresponds to a magnification factor of one billion (1,000,000,000 or 109). ...

Event Horizon Telescope Observations of the Jet Launching
and Collimation in Centaurus A
~ EHT Collaboration, Michael Janssen et al
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Re: EHT Pinpoints Dark Heart of the Nearest Radio Galaxy

Post by neufer » Tue Jul 20, 2021 4:17 am

Art Neuendorffer