Using JWST, the team pinpointed the precise location of the “motor” of the merging galaxy IIZw096. Nearly 500 million light-years away, near the constellation Delphinus, IIZw096 is the site of a spectacular burst of star formation, alluded to by the red speckles near the center of the image.
Corresponding author Hanae Inami, assistant professor at Hiroshima University’s Hiroshima Astrophysical Science Center, said: “The James Webb Space Telescope has given us a completely new view of the universe thanks to the highest spatial resolution ever and sensitivity in the infrared. We wanted to find the ‘motor’ that is driving this merging galaxy. We knew this source was deeply hidden by cosmic dust, so we couldn’t use visible or ultraviolet light to find it. Only in the mid-infrared, observed with the James Webb Space Telescope, are we now seeing this source outshine everything else in these merging galaxies.”
Stars, planets and other galactic components can collide as they merge, providing material for new celestial events. Most of these galactic collisions produce only infrared light, which is invisible to humans and has longer wavelengths than visible light. The same team found in 2010 that the amalgamation system was dominated by infrared emission from solids using the Spitzer Space Telescope. The telescope’s poor resolution prevented the scientists from pinpointing the exact location of the engine, despite being able to measure the engine’s power as the source of the light.
Co-author Thomas Bohn of Hiroshima University said: “Using the James Webb Space Telescope, they found that this engine is responsible for most of the mid-infrared emission, which accounts for up to 70% of the system’s total infrared emission. They also found that the source has a radius that is not is larger than 570 light-years – a small fraction of the size of the merger system, which is about 65,000 light-years across, indicating that the energy is confined to a small space.”
“Intriguingly, this compact source, far from the galactic centers, dominates the infrared brightness of the system.”
“This resource contributes significantly to galaxy mergers despite being in the suburbs, like a speck of pepper on the white of a fried egg.”
Inami asked, “We want to know what’s driving this source: is it a starburst or a massive black hole? We’ll be using infrared spectra taken with the James Webb Space Telescope to investigate. It’s also unusual for the ‘engine’ to be outside the main parts of the merging galaxies, so we’ll investigate how this powerful source got there.”
In addition to locating the engine, the researchers discovered 12 light “lumps.” Five of these were first found using the James Webb Space Telescope. However, several of them had already been discovered by the near-infrared capabilities of the Hubble Space Telescope. According to Inami, these release mid-infrared light that could be the beginnings of stars.
Inami said, “The mid-infrared imaging from the James Webb Space Telescope described in this paper revealed a hidden aspect of the merging galaxy IIZw096 and opened a door to identifying heavily dust-obscured sources not found at shorter wavelengths. Future planned spectroscopic observations of IIZw096 will provide additional information about the nature of the dust, ionized gas, and warm molecular gas in and around the perturbed region of this luminous merging galaxy.”
Magazine reference:
- Hanae Inami, Jason Surace, et al. OBJECTIVES-JWST: Unveiling dusty compact sources in the merging galaxy IIZw096. The Astrophysical Journal Letters. DOI: 10.3847/2041-8213/ac9389
