Astronomers Pinpoint The Mysterious 'Engine' of a Super-Powerful Intergalactic Light

Recently, a strong infrared light that is emanating from two galaxies that are merging has been ripped out of hiding.

Astronomers have located the light's precise position, hidden by a substantial wall of dust that blocks it from view at other wavelengths, using the JWST. While the source of the light is still unknown, focusing on its location will help researchers identify it and understand why it shines so brilliantly compared to expectations.

Because it has the best spatial resolution and infrared sensitivity ever, the James Webb Space Telescope has given us entirely new perspectives on the Universe, according to astronomer Hanae Inami of Japan's Hiroshima Astrophysical Science Center.

"We sought to identify the "engine" driving this galaxy system that is merging. We were aware that neither visible nor ultraviolet light could be used to locate this source since it was heavily obscured by cosmic dust. We can only now see that this source outshines every other object in these merging galaxies in the mid-infrared, thanks to observations made with the James Webb Space Telescope."

Even though the majority of the universe is made up of empty space, galaxy mergers do occasionally occur. The unstoppable pull of gravity causes massive galaxies to be brought together, merging to create bigger galaxies.

The Milky Way itself is a cosmic Frankenstein's monster, partially made up of all the other galaxies it has absorbed over the course of its billions of years of existence. It's not even some faraway event that only occurs to other galaxies elsewhere.

There have been many instances of galaxy mergers in the larger Universe, but they are a lengthy process that can take millions to billions of years.

The only additional examples are single frames from related but unlike films, therefore scientists must use the examples we already have and recreate the history around them. Although laborious, it's one of the greatest resources we have for comprehending galaxy mergers.

We also know that these mergers are rather active based on the light they generate. Despite the fact that galaxies are primarily made of space, stars can collide or interact gravitationally, which can cause orbital disruption.

The star-forming gas clouds between the stars can also collide with one another, creating shock waves that can unleash ferocious waves of star formation known as starbursts, which can be seen as infrared light shining out of dust clouds.

When astronomers pointed the infrared Spitzer Space Telescope towards the IIZw096 galaxy merger, 500 million light-years distant, in 2010, they anticipated seeing something similar.

They discovered a brilliant infrared light glowing in the center of the continuing collision as an alternative. Unfortunately, Spitzer's resolution was insufficient to determine the precise position of the light source, thus the mystery had to be forgotten.

This is because Spitzer was the best telescope available at the time, and no other telescope had a chance of getting closer since longer infrared light wavelengths do not scatter off dust the same way that shorter wavelengths do. The JWST then arrived, and Inami and her coworkers proceeded to take a closer look.

They discovered that almost 70% of the mid-infrared light released by the merging galaxies originates from the source. Additionally, the infrared source has a maximum radius of 570 light-years despite the fact that the two galaxies collectively cover roughly 65,000 light-years. This shows that the emission's source is relatively small.

We are aware that supermassive black holes in the cores of galaxies may merge when they come into contact, and that the region surrounding an active black hole releases a great deal of light. However, the light's placement is odd; it's not near each galaxy's core, which is where you'd typically expect to find such a black hole.

We are interested in learning if this source is a starburst or a large black hole. Says Inami.

"We will look into this using infrared spectra obtained by the James Webb Space Telescope. We will investigate how this potent source arrived up there because it is likewise rare for the "engine" to be located outside of the major regions of the merging galaxies."

In the JWST data, the researchers also discovered 12 more smaller sources of mid-infrared light grouped around the prominent "engine." Five of the smaller clusters were brand-new, albeit some of them had previously been observed in Hubble's near-infrared data.

They are less enigmatic—the light profile is consistent with starburst activity—but they do suggest that there is an intense event occurring when the two galaxies collide.

The experts anticipate that further investigation will reveal the location of the mystifyingly brilliant light's origin. More observations are being planned to describe the gas and dust in and around the strange collision, which is still occurring.

The research has been published in The Astrophysical Journal Letters.