Images Show Supermassive Black Hole Blowing Powerful Winds Into Galaxy

Astronomers have captured images that show powerful winds driven by a supermassive black hole into its surrounding galaxy. The findings may help scientists to understand the effect such outflows have on star formation and the evolution of galaxies.

To investigate this phenomenon, a team led by National Science Foundation NOIRLab astronomer Stéphanie Juneau studied the galaxy NGC 7582, located around 70 million light-years from Earth.

Not only is this spiral galaxy home to a supermassive black hole at its heart, but that tremendous cosmic event is also greedily consuming material from its immediate surroundings.

In the churning discs that surround the feeding black hole, matter is heated, which creates violent and powerful outflows of material or winds, giving rise to a region that astronomers and astrophysicists call active galactic nuclei (AGN).

Juneau and her team wanted to address the effect this has on NGC 7582 and particularly on its regions of star formation.

The astronomers discovered that the structure of the galaxy could be protecting the surroundings from these powerful winds while shaping them into cone-like outflows. They even suggest this structure could be the result of NGC 7582 having undergone a minor merger with another galaxy in its history.

Juneau told Newsweek: "Black hole winds are such an energetic phenomenon that they could potentially blow most of the gas out of the galaxies in which they reside. Ultimately, this would prevent galaxies from forming any new stars by removing or heating up their gas reservoir, and their current population of stars would simply keep aging without any new stellar births. We sometimes refer to this as a galaxy's death in a stellar population sense.

"There are still many mysteries around supermassive black holes, including how exactly they launch those winds, and whether they are a smoking gun evidence that supermassive black holes influence the growth and evolution of galaxies."

Thus far, theories suggest that outflows from supermassive black holes, which dwell at the center of most, if not all, galaxies, impact on the gas reservoirs of galaxies that serve as the building blocks for stars. This, in turn, regulates star formation.

In cosmological simulations performed by researchers on Earth, factoring in this phenomenon has helped to restrict the number of star-forming galaxies to those observed in the actual Universe.

By mapping the motion of stars and gas in NGC 7582, the astronomers discovered that galactic substructure plays an important role in shaping the winds into narrow outflows, or jets.

They also found that the galactic structure around the supermassive black hole may have the effect of protecting the rest of the galaxy from the harsh outflow of energetic material from the AGN, instead, diverting it away as a powerful wind.

Juneau added: "Historically, the main hypothesis has been that black hole winds are collimated by a donut-shaped 'torus' structure just around the black hole itself with a much smaller opening and this torus can be aligned randomly with respect to the galaxy.

"In the case of the galaxy that we studied, NGC 7582, it instead appears that the ring may 'protect' the galaxy by directing the winds away from it, which is an exciting new scenario to investigate."

The team used the Multi-Unit Spectroscopic Explorer (MUSE) instrument, which is part of the European Southern Observatory's Very Large Telescope (VLT), located in the Atacama Desert region of Northern Chile, to reach their findings.

MUSE allowed Juneau and her colleagues to capture images that showed the distribution of different ionized element—atoms like hydrogen and oxygen with electrons stripped from their outer shells—in NGC 7582.

 NGC 7582
Images of NGC 7582 captured by the MUSE instrument on the VLT. The right shows ionized distributed throughout the galaxy. The left provides a more traditional view of the galaxy. Juneau et al/ESO

On the right above, an image shows the blue-colored cone-shaped material blown out of the AGN, containing oxygen, nitrogen and hydrogen in blue, green and red, respectively. The glowing red areas in the image mark regions of high star formation activity.

The image on the left above, shows the same area, albeit in a more "classical view" of this galaxy. In this image dust lanes obscure blue and orange starlight making the activity of the AGN more difficult to observe.

In a paper published in The Astrophysical Journal, Juneau and her co-authors tentatively concluded that the structure protecting star-forming regions in NGC 7582 from powerful outflows could be the result of a minor galaxy merger or a central galactic bar composed of densely clustered stars. The latter type of structure is common, found in around half of all spiral galaxies.

The team added that to better understand this phenomenon and its effect on star formation and galactic evolution, more research regarding the role of galaxy substructure in controlling the fueling, feedback and obscuration of AGNs is important.

Juneau concludes: "Next for NGC 7582, we hope to obtain higher-resolution observations to 'zoom in' and decipher what is happening between the black hole itself and the ring.

"Being able to observe this in situ would prove our interpretation that galaxy substructure can help protect the galaxy itself—its reservoir of gas clouds out of which new stars form—from the influence of an energetic giant black hole."

Update 02/10/22, 6:00 a.m. ET: This article was updated to add comments by Stéphanie Juneau

Supermassive Black Hole
An artist's impression of a supermassive black hole feeding on material and belching out powerful jets of gas. New research has looked into the effect that winds from supermassive black holes have on the evolution of their surrounding galaxies. Nustar-Caltech/NASA