A supermassive black hole’s dust ring will cast shadows at the centre of a galaxy.


At sunset, when sunlight penetrates the clouds and produces a combination of light and dark rays produced by the shadows of the clouds and the light rays scattered by the atmosphere, some of the most breathtaking views of our sky occur.

In NASA’s Hubble Space Telescope images, astronomers studying the nearby galaxy IC 5063 are fascinated by a similar impact.

In this scenario, a series of narrow, light rays and dark shadows are seen radiating from the active galaxy’s glaringly bright center.

In Cambridge, Massachusetts, a team of astronomers led by Peter Maksym of the Center for Astrophysics | Harvard & Smithsonian (CfA) traced the beams to the centre of the galaxy, the site of an active supermassive black hole.

A black hole is a dense, compact space area that, under the crushing pull of gravity, swallows light and matter.

The monster entity frenetically feeds on incoming material, producing in its vicinity a huge beam of light from superheated gas.

While several possible hypotheses for the light show have been established by scholars, the most intriguing explanation suggests that an inner tubular ring, or torus, of dusty material circling the black hole casts its shadow into space.

The dust disk around the black hole does not block all light, according to the scenario suggested by Maksym. Gaps in the disk make it possible for light to radiate outward, producing bright, cone-shaped rays that are similar to light fingers often seen at sunset. The rays in IC 5063, however, take place on a much larger scale, firing at least 36,000 light-years wide.

In the ring, some of the light hits thick patches, throwing the shadow of the ring into space.

Like dark finger shapes interspersed with light rays, these shadows emerge.

These rays and shadows are apparent because, relative to the galaxy’s plane, the black hole and its ring are tilted sideways.

This orientation allows the light rays to extend well beyond the galaxy.

A rare insight into the distribution of material surrounding the black hole offers this interplay of light and shadow.

The material could resemble scattered clouds in some places.

The observations could provide an indirect hint to the mottled structure of the disk if this interpretation were accurate.

“I’m most excited about the idea of the torus shadow because it’s a really cool effect that I don’t think we’ve ever seen in images, even though it’s a hypothesis,” Maksym said. Scientifically, it tells us something that is difficult to see explicitly – usually unlikely.

We know this phenomenon can occur, but we can see the consequences in the galaxy in this case. Learning more about the torus’ geometry would have implications for those seeking to understand the behavior and atmosphere of supermassive black holes.

When a galaxy evolves, the central black hole forms it.

It’s necessary to research the torus because it funnels material into the black hole.

The dark rays provide indirect evidence that the disk in IC 5063 could be very thin if the “shadow” interpretation is right, explaining why light leaks out around the structure.

NASA’s Chandra X-ray Observatory’s observations of identical black holes have observed X-ray light escaping from holes in the torus, making the structure appear like Swiss cheese.

The holes may be caused by internal forces bending the disk, causing it to warp, Maksym said. “It is possible that the warping could create gaps large enough for some light to shine through, and as the torus rotates, light rays could sweep across the galaxy like lighthouse beams through the nebula,” he said.

Serendipity of Citizen Science
While scientists have been observing the galaxy for decades, the shocking finding took a non-scientist to make. As she was post-processing Hubble images of the galaxy in December 2019, Judy Schmidt, an artist and amateur astronomer from Modesto, California, discovered dark shadows. For fascinating insights that she can convert into beautiful pictures, Schmidt regularly scours the Hubble archive. She shares these photos with her several fans, which include astronomers like Maksym, on her Twitter account.

Schmidt chose IC 5063’s Hubble observations from the database because she is interested in active galaxies.


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