An international team of astronomers has applied a new technique to a group of galaxies and the faint light between them — known as “intragroup light” — to describe the stars that inhabit them.
The lead author of the study was published in MNRASDr Cristina Martínez-Lombilla, from UNSW’s School of Physics, said: “We know next to nothing about intragroup light.
“The brightest part of the group is about 50 times dimmer than the darkest night sky on Earth. It is difficult to detect even with the largest telescopes on Earth or in space.”
Using their sensitive technique, the researchers eliminated light from all objects except the intragroup light, which the researchers not only detected, but were able to study and tell the story of the stars that inhabit them.
“We analyzed the properties of the stars in the group – those meteors between Milky Way. We studied the age and abundance of the elements that make them up, and then compared these signatures to stars that are still part of the galaxy group,” said Dr Martinez-Lumbila.
“We found that the light in the group is younger and less metallic than the surrounding galaxies.”
Reconstruct the story of light in the group
Not only are the lone stars in the group’s light “out of place,” but they appear to have a different origin than their nearest neighbors. The researchers found that the signatures of stars within the cluster look similar to the nebula-like “tails” of more distant galaxies.
The combination of these clues allowed the researchers to reconstruct the history of light within the group — the story — and how its stars came together in their own stellar orphanages.
“We think that these individual stars were stripped from their galaxies at some point and that they now float freely with the gravitational pull of the group,” said Dr. Martínez-Lombilla. “This stripping, called tidal stripping, is caused by massive Caused by the passage of satellite galaxies — similar to the Milky Way — which pull stars into their wakes.”
This is the first time the intragroup light of these galaxies has been observed.
Dr Martínez-Lombilla said: “Revealing the amount and origin of light within a group provides a fossil record of all interactions experienced by a group of galaxies and provides a holistic view of the system’s interaction history.”
“Moreover, these events happened a long time ago. The galaxy [we’re looking at] So far away that we’re seeing them as they were 2.5 billion years ago. This is how long it takes for their light to reach us. “
By observing events that occurred long ago in distant galaxies, researchers are providing important data points for the slow evolution of cosmic events.
Tailor-made image processing programs
The researchers have pioneered a unique technique to achieve this penetrating view.
“We developed a custom image processing program that allows us to analyze the faintest structures in the universe,” said Dr. Martínez-Lombilla.
“It follows the standard procedure for studying faint structures in astronomical images – this means modeling in 2D and removing all light, except light from ingroup light. This includes all bright stars in the image, galaxies blurring ingroup light and subtract the continuum radiance from the sky.
“What sets our technique apart is that it’s entirely Python-based, so it’s very modular and easily adaptable to different datasets from different telescopes, not just for these images.
“The most important result is that when studying very faint structures around galaxies, every step in the process counts and every unwanted light should be accounted for and removed. Otherwise, your measurements will be Incorrect.
Dr. Martínez-Lombilla said the technique presented in this study is a pilot to encourage future analysis of light within groups.
“Our main long-term goal is to extend these results to a large sample of galaxy groups. We can then look at the statistics and find out what is typical about the formation and evolution of light within the group and these extremely common groups of galaxies.
“This is critical work in preparation for the next generation of deep all-sky surveys, such as those conducted with the Euclid Space Telescope and LSST with the Vera C. Rubin Observatory.”