Nasa’s Webb telescope helps identify energy source behind strange colliding galaxies

Astronomers have identified the precise location of the powerful energy source behind a luminous merging galaxy hundreds of millions of light years away.

The main energy source behind this colliding galaxy IIZw096 – located about 500 million light years away near the constellation Delphinus – had been shrouded by cosmic dust, say researchers, including those from Hiroshima University in Japan.

While the energy source was first identified previously about a decade ago, now using the more advanced James Webb Space Telescope, scientists have pinpointed the exact location of what they call the “engine” of the merging galaxy.

The findings, published recently in the The Astrophysical Journal Letters, unravel where the majority of the visible radiation from the colliding system emerges.

“The James Webb Space Telescope has brought us completely new views of the universe thanks to it having the highest ever spatial resolution and sensitivity in the infrared,” study corresponding author Hanae Inami said.

“We wanted to find the ‘engine’ that powers this merging galaxy system. We knew that this source was deeply hidden by cosmic dust, so we could not use visible or ultraviolet light to find it,” Dr Inami explained.

But observing the emission from these merging galaxies in the mid-infrared wavelength using the Webb telescope, scientists could find that this “engine” behind the collision “outshines everything else”.

When galaxies collide, their constituent stars, planets and other celestial bodies smash into each other, but these cosmic collisions only emit radiation in the infrared range that has longer wavelengths than the light visible to humans.

In previous studies in 2010 using the Spitzer Space Telescope, astronomers could not identify the exact location of the main source – engine – of the radiation due to the telescope’s limited resolution.

But with the Webb telescope, they found that this engine is responsible for the bulk of the mid-infrared emission, which accounts for up to 70 per cent of the total infrared emission of the system.

Astronomers could also find that this energy source has a relatively very small radius no larger than 570 light years – only a tiny fraction of the colliding system that spans 65,000 light years across.

Scientists liken this proportion to “a speck of pepper on the white of a fried egg”.

“It is intriguing that this compact source, far from the galactic centers, dominates the infrared luminosity of the system,” said Thomas Bohn, another co-author of the study.

The findings, according to researchers, also reveal the potential of the Webb telescope to open door towards identifying heavily dust-obscured cosmic energy sources.

“Future planned spectroscopic observations of IIZw096 will provide additional information on the nature of the dust, ionized gas, and warm molecular gas in and around the disturbed region of this luminous merging galaxy,” Dr Inami added.