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.
