Home Science Astronomers observe intra-group light—the elusive glow between distant galaxies

Astronomers observe intra-group light—the elusive glow between distant galaxies

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Light in the “between” groups of galaxies, or “intragroup light,” no matter how dim, is emitted from stars stripped from their home galaxies. Image: Arrived. Credit: Martínez-Lombilla et al./UNSW Sydney

An international team of astronomers has applied a new technique to galaxy groups and the faint light between them (known as “intragroup light”) to characterize the stars that live there.

First author of a study published in MNRASDr Cristina Martínez-Lombilla, Department of Physics, UNSW Science, said:

“The brightest part of the light in the group is 50 times dimmer than the darkest night sky on Earth. It’s very difficult to detect, even with the largest telescopes on Earth or in space.”

Using a highly sensitive technique that excludes light from all objects other than light within the group, researchers not only detected light within the group, but were able to study and tell the stories of the stars that live within them. I made it.

“We analyzed the properties of the stars in the group—those stray stars Between galaxy group. They examined the age and abundance of the elements that make up them, and compared their characteristics to those that still belong to the stars today. galaxy groupsaid Dr. Martínez-Lombilla.

“We found that the light within the group was younger and less rich in metal than the surrounding galaxy.”

Reconstructing the story of light within the group

The orphan star of the intragroup light was not only “anachronistic” but also appeared to have a different origin than its nearest neighbors. The researchers found that the features of the stars in the group resembled the vague “tails” of distant galaxies.

Combining these clues allowed researchers to reconstruct the history of light within the group, the story of how the star came to be collected in its own star orphanage. .

“These individual stars are thought to have been stripped from their home galaxy at some point and now float freely according to collective gravity,” said Dr. Martínez-Lombilla. “The stripping, called tidal stripping, is caused by the passage of giant satellite galaxies, similar to the Milky Way, and pulls in the stars.”

This is the first time that intragroup light in these galaxies has been observed.

“By clarifying the amount and origin of light within the group, fossil record It provides a complete picture of the interaction history of the system, among all the interactions that groups of galaxies have undergone,” said Dr. Martínez-Lombilla.

“Also, these events occurred long ago. [we’re looking at] It’s so far away that it looks the same as it did 2.5 billion years ago. That’s how long it takes their light to reach us. ”

By observing events in galaxies long ago, researchers are providing important data points for the slow evolution of cosmic events.

Customized image processing procedure

Researchers have developed a unique technique to achieve this sharp field of view.

“We have developed a tailored image processing procedure that allows us to analyze the faintest structures in the universe,” said Dr. Martinez Lombira.

“This follows standard procedures for studying faint structures in astronomical images. This implies 2D modeling and the removal of all light except that coming from within the group. contains all bright lights. Performer In the image, the galaxies obscuring the light in the group and the subtraction of the continuum emission from the sky.

“What sets our technology apart is that it is completely Python-based, which makes it very modular and useful not only for these images, but also for different data sets from different telescopes. can be applied to

“The most important result is that when studying the very dark structures around galaxies, every step in the process is critical and all unwanted light must be considered and removed. If you don’t do that, Otherwise, the measured value will be wrong.

Martínez-Lombilla said the technique presented in this study is experimental and encourages future analyzes of intragroup light.

“Our main long-term goal is to extend these results to a large sample of galaxy groups. We can then examine the statistics to find typical properties of the formation and evolution of galaxies within the group.” I can do it. light And these very common systems in groups of galaxies.

“This is important work to prepare for the next generation of deep all-sky surveys, such as those performed by the Euclid Space Telescope and the Vera C. Rubin Observatory’s LSST.”

For more information:
Cristina Martínez-Lombilla et al., Galaxy And Mass Assembly (GAMA): Dilation of intragroup light within groups at z = 0.2 from deep Hyper Suprime-Cam images, Monthly Notices of the Royal Astronomical Society (2022). DOI: 10.1093/mnras/stac3119

Quote: Astronomers Observe Light in Swarm — Elusive Glow Between Distant Galaxies (24 Nov 2022) on 24 Nov 2022 https://phys.org/news/ Retrieved from 2022-11-astronomers-intra-group-lightthe-elusive-distant.html

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