Breakthrough in unusual galaxy may help unravel the mystery of dark matter

Within the picture above, a faint path of stars will be seen stretching throughout the galaxy. These constructions, referred to as globular cluster stellar streams, are coherent stellar constructions that retain a document of their dynamical historical past and may present distinctive insights into the evolution of galaxies and the character of darkish matter.

Globular cluster stellar streams provide astronomers a singular alternative to map in any other case invisible darkish matter and examine the way it behaves. For a few years they’ve been troublesome to watch as a result of they’re extraordinarily faint. Nonetheless, advances in giant astronomical datasets and complex evaluation strategies have not too long ago made stellar streams one of the vital promising instruments in galactic astronomy.

Now, PhD scholar Julie Kiel Holm from the Niels Bohr Institute and Affiliate Professor Sarah Pearson from DTU Area, along with a global group of researchers, have made a discovery that has by no means been seen earlier than. Their findings have simply been printed in Nature, one of many world’s most prestigious scientific journals.

“We’ve got found a globular cluster stellar stream in one other galaxy. That is the primary time such a stream has been noticed outdoors our personal galaxy, the Milky Manner, which makes the invention significantly thrilling,” says Julie Kiel Holm.

Globular cluster stellar streams are extraordinarily troublesome to detect past the Milky Manner as a result of their sign is so faint. On this case, the stream was recognized in an ultra-diffuse galaxy, a category of galaxies that emit little or no gentle.

It’s exactly the mix of those two components that makes the invention so exceptional.

“This opens completely new prospects. Not solely can we now seek for globular cluster stellar streams in different galaxies, however in the long run, we may additionally have the ability to measure the darkish matter content material of extra ultra-diffuse galaxies,” says co-author Sarah Pearson, who contributed to the invention throughout her employment on the Niels Bohr Institute.

A brand new device for mapping darkish matter

The importance of the invention lies not solely within the detection itself. The researchers additionally display, for the primary time, that globular cluster stellar streams can be utilized as a device for measuring darkish matter in galaxies past the Milky Manner. That is vital as a result of darkish matter makes up many of the mass within the Universe, but its nature stays unknown.

“We present {that a} well-established device from research of the Milky Manner can be utilized to grasp different galaxies, the place measuring the distribution of darkish matter has historically been very difficult,” says Julie Kiel Holm.

The researchers studied the ultra-diffuse galaxy UGC9050-Dw1 and so they current new estimates of how its mass is distributed and the way a lot mass it comprises. Their analyses point out that the galaxy comprises giant quantities of darkish matter, as anticipated for ultra-diffuse galaxies.

“Our outcomes are according to earlier research and what they’ve proven about darkish matter on this ultra-diffuse galaxy. We’re measuring it with a very new device, demonstrating that this methodology additionally works past our personal galaxy,” says Julie Kiel Holm.

A single discovery may assist clarify the universe

Though the examine focuses on a single galaxy, its broader significance lies in the opportunity of gaining a deeper understanding of darkish matter itself. By establishing globular cluster stellar streams as a sensible device past the Milky Manner, researchers could finally have the ability to map darkish matter throughout a variety of galaxy varieties.

“The insights into darkish matter that we’ve got beforehand been in a position to acquire from globular cluster stellar streams have been restricted to a single galaxy – our personal. Having the ability to observe these streams in completely completely different sorts of galaxies opens the door to utilizing them to construct a wider understanding of how darkish matter behaves,” says Julie Kiel Holm.

With new and upcoming amenities such because the Euclid Area Telescope and the Nancy Grace Roman Area Telescope, the researchers anticipate the variety of observable globular cluster stellar streams to extend dramatically.

[[ Fact Box 1: What is a globular cluster stellar stream?

A globular cluster stellar stream is a long, narrow stream of stars originating from a globular cluster – a dense, gravitationally bound collection of stars.

The stream forms when the gravitational forces of a host galaxy gradually strip stars from the globular cluster in a process known as tidal stripping.

Because stellar streams are shaped by gravity, astronomers can use them to investigate how mass is distributed within galaxies. They provide valuable information about dark matter, which accounts for approximately 80-85 percent of all matter in the universe but whose nature remains unknown.

Fact Box 2: About the study

The paper reports the first discovery of a globular cluster stellar stream beyond the Milky Way.

The researchers also demonstrate how such streams can be used to constrain the dark matter halo mass and dark matter density profile of external galaxies.

The study has been published in Nature.

The following authors contributed to the study: Julie Kiel Holm, Sarah Pearson, Jacob Nibauer, David J. Sand, Adrian M. Price-Whelan, Tjitske Starkenburg, David Hendel and Catherine Fielder.

The study is funded by the Villum Foundation and the European Research Council. ]]