JUN 22, 2021 10:07 AM PDT

An Unusual Galaxy Without Dark Matter

WRITTEN BY: Carmen Leitch

Even though we still cannot detect dark matter, many researchers are confident that exists. It seems to act as a kind of glue that binds galaxies together and exerts a powerful influence on the conventional matter that we can detect easily. It's also been suggested that dark matter is an essential part of galaxies. But new research has identified a galaxy that does not bear any of the standard hallmarks of dark matter. This ultra-diffuse galaxy (UDG) is called NGC1052-DF2 (DF2), and scientists believe that the galaxy, which is at a distance of about 22.1 +/-1.2 megaparsecs, does not contain dark matter.

NGC1052-DF2 / Credit: NASA, ESA, Z. Shen and P. van Dokkum (Yale University), and S. Danieli (Institute for Advanced Study)

"Determining an accurate distance to DF2 has been key in supporting our earlier results," said study co-leader Shany Danieli, a NASA Hubble Fellow at the Institute for Advanced Study. "The new measurement reported in this study has crucial implications for estimating the physical properties of the galaxy, thus confirming its lack of dark matter."

This work is based on data collected during  40 orbits of NASA's Hubble Space Telescope. The findings have been reported in Astrophysical Journal Letters.

"We went out on a limb with our initial Hubble observations of this galaxy in 2018," noted study co-leader Pieter van Dokkum of Yale University. The team's 2018 research used  "surface brightness fluctuations" to measure distance.  "I think people were right to question it because it's such an unusual result. It would be nice if there were a simple explanation, like a wrong distance. But I think it's more fun and more interesting if it actually is a weird galaxy."

In 2019, the team measured the distance between D2 and a neighbor, UDG NGC1052-DF4 (DF4), which also suggested that there wasn't any dark matter. This study has confirmed that research and has refined their initial measurements; the galaxies are probably a bit further apart than the scientists first thought, which actually strengthens the case that there's no dark matter there.

The motion of stars in DF2 and DF4 can be explained solely by stellar mass, which indicates that there is no unseen force - like dark matter - acting on the bodies. Finding galaxies that lack dark matter might help us learn more about it, and how galaxies grow.

DF2 and DF4 are both about the size of the Milky Way but they only contain about one percent of the mass the Milky Way holds. They are ultra-diffuse, and they also have a large amount of especially luminous globular clusters.

"There's a saying that extraordinary claims require extraordinary evidence, and the new distance measurement strongly supports our previous finding that DF2 is missing dark matter," said study co-leader Zili Shen of Yale University. "Now it's time to move beyond the distance debate and focus on how such galaxies came to exist."

Sources: AAAS/Eurekalert! via Institute for Advanced Study, Astrophysical Journal Letters

About the Author
  • Experienced research scientist and technical expert with authorships on over 30 peer-reviewed publications, traveler to over 70 countries, published photographer and internationally-exhibited painter, volunteer trained in disaster-response, CPR and DV counseling.
You May Also Like
JUN 08, 2021
Space & Astronomy
Physicists Find Definitive Proof of What Causes the Northern Lights
JUN 08, 2021
Physicists Find Definitive Proof of What Causes the Northern Lights
The auroras that are the northern lights have captured the imagination of people for thousands of years. While theories ...
JUL 08, 2021
Space & Astronomy
Giant Plumes on Saturn's Moon May Hold Signs of Life
JUL 08, 2021
Giant Plumes on Saturn's Moon May Hold Signs of Life
Saturn’s moon, Enceladus, has giant erupting plumes of water that, scientists say, can not be explained by known g ...
JUL 20, 2021
Space & Astronomy
The Moon Landing, 52 Years Later
JUL 20, 2021
The Moon Landing, 52 Years Later
On July 16, 1969 the Apollo 11 spacecraft was launched from Cape Canaveral (Cape Kennedy) Florida. Four days later, astr ...
SEP 01, 2021
Chemistry & Physics
New Study Suggests One-third of Binary Stars Have Engulfed Their Planets
SEP 01, 2021
New Study Suggests One-third of Binary Stars Have Engulfed Their Planets
While our solar system is relatively calm and inert, some sun-like stars out there will literally eat the planets in the ...
SEP 14, 2021
Chemistry & Physics
The World's Most Accurate Clock
SEP 14, 2021
The World's Most Accurate Clock
The world’s most accurate clock has taken the 2022 Breakthrough Prize in Fundamental Physics. Jun Ye, a physicist ...
SEP 22, 2021
Chemistry & Physics
XENON1T Physicists May Have Directly Detected Dark Energy
SEP 22, 2021
XENON1T Physicists May Have Directly Detected Dark Energy
In what could be a revolutionary discovery, a team of physicists from the XENON Collaboration may have detected dark ene ...
Loading Comments...