Our Galaxy's Supermassive Black Hole Could Be Pointing A Relativistic Jet Right At Us


Things are officially getting exciting. Sagittarius A *, the supermassive black hole at the center of the Milky Way, and it's pony-ponging at the galaxy's dusty heart.

The picture below is the best picture yet of Sgr A *, and it may look like just a weird blob of light to you, astrophysicists studying the radio data can learn a lot from what they're looking at – and they think they've identified a relativistic jet angled towards Earth.

Because the image is taken from the cloud, it is scattered by the cloud.

Astrophysicist Eduardo Ros of the Max Planck Institute for Radio Astronomy in Germany said. "The galactic center is in the black hole, which acts like frosted glass New scientist,

Using very long baseline interferometry to take observations at a wavelength of 3.5 millimeters (86 GHz frequency), a team of astronomers has used computer modeling to simulate what's inside the thick cloud of plasma.

blackhole vlbi 35mm(Issaoun, M. MoŇõcibrodzka, Radboud University / M.D. Johnson, CfA)

above: The bottom right image shows Sgr A * as seen in the data. The top images are simulations, while the bottom left is Sgr A * with the scattering removed.

It revealed that Sgr A * s radio emission comes from a smaller region than previously thought.

300 years of a night sky, with a symmetrical shape. And, since black holes do not emit detectable radiation on their own, the source is most likely one of two things.

"This may indicate that the radio emission is produced in a disc of incident gas rather than by a radio jet," said astrophysicist Sara Issaoun of Radboud University in The Netherlands.

"However, that would make Sgr A * an exception to other radio black holes." The alternative could be the radio jet is pointing almost at us. "

Active black holes are covered by a swirling cloud of material. This material is swallowed by the black hole, it emits jets of particles from its rotational poles at velocities approaching light speed.

We're not quite sure how this happens, but astronomers believe that material from the inner part of the accretion disc is channeled towards and launched from the poles via magnetic field lines.

Since Earth is in the galactic plane, having a jet pointed in our direction would mean that the black hole is oriented quite strangely, as if it's lying on its side. (Nearby galaxy Centaurus A, for instance, has jets shooting perpendicular to the galactic plane.)

But this orientation has been hinted at before. Last year the GRAVITY Collaboration described flares around Sgr A * consistent with something orbiting it face-on from our perspective – like looking at the solar system from above.

So "Maybe this is true after all," said Radboud University astronomer Heino Falcke, "and we're looking at this beast from a very special vantage point."

Hopefully, when the Horizon Telescope releases the first images of Sgr A * s event horizon – something we are looking forward to – they will reveal more. And, in case you were starting to get worried, the 1.4-millimeter wavelength (230 GHz) wants to reduce the light scattering by a factor of 8.

This means the long-awaited picture of the shadow of a black hole will – hopefully – be breathtakingly detailed.

Meanwhile, studying data as a result of this help build a comprehensive picture of how to solve this mysterious cosmic objects work.

"Understanding how black holes work … takes more than the picture of its shadow. "It takes observations at many different wavelengths (radio, X-ray, infrared, etc.) to piece together the entire story, so every piece counts!"

The team's paper has been published in The Astrophysical Journal, and can read in full on arXiv.



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