Dark matter goes missing in oddball galaxy

Galaxies and dark matter fit like peanut butter and jelly. You generally do not discover one without the other.

For that reason, scientists were shocked when they discovered a galaxy that is missing out on most, if not all, of its dark matter. An undetectable compound, dark matter is the underlying scaffolding upon which galaxies are constructed. It’s the glue that holds the noticeable matter in galaxies – stars and gas – together.

” We believed that every galaxy had dark matter which dark matter is how a galaxy starts,” stated Pieter van Dokkum of Yale University in New Sanctuary, Connecticut, lead scientist of the Hubble observations. “This undetectable, mystical compound is the most dominant element of any galaxy. So discovering a galaxy without it is unforeseen. It challenges the basic concepts of how we believe galaxies work, and it reveals that dark matter is genuine: it has its own different presence apart from other elements of galaxies. This outcome likewise recommends that there might be more than one method to form a galaxy.”

The distinct galaxy, called NGC 1052- DF2, includes at many 1/400 th the quantity of dark matter that astronomers had actually anticipated. The galaxy is as big as our Galaxy, however it had actually gotten away attention due to the fact that it includes just 1/200 th the variety of stars. Offered the things’s plus size and faint look, astronomers categorize NGC 1052- DF2 as an ultra-diffuse galaxy. A 2015 study of the Coma galaxy cluster revealed these big, faint challenge be remarkably typical.

However none of the ultra-diffuse galaxies found up until now have actually been discovered to be doing not have in dark matter. So even amongst this uncommon class of galaxy, NGC 1052- DF2 is an oddball.

Van Dokkum and his group found the galaxy with the Dragonfly Telephoto Variety, a custom-made telescope in New Mexico they created to discover these ghostly galaxies. They then utilized the W.M. Keck Observatory in Hawaii to determine the movements of 10 huge groupings of stars called globular clusters in the galaxy. Keck exposed that the globular clusters were moving at reasonably low speeds, less than 23,000 miles per hour. Stars and clusters in the borders of galaxies consisting of dark matter relocation a minimum of 3 times quicker. From those measurements, the group determined the galaxy’s mass. “If there is any dark matter at all, it’s little,” van Dokkum discussed. “The stars in the galaxy can represent all the mass, and there does not appear to be any space for dark matter.”

The scientists next utilized NASA’s Hubble Space Telescope and the Gemini Observatory in Hawaii to reveal more information about the distinct galaxy. Gemini exposed that the galaxy does disappoint indications of an interaction with another galaxy. Hubble assisted them much better recognize the globular clusters and determine a precise range to the galaxy.

The Hubble images likewise exposed the galaxy’s uncommon look. “I invested an hour simply looking at the Hubble image,” van Dokkum remembered. “It’s so unusual, especially nowadays after many years of Hubble, that you get a picture of something and you state, ‘I have actually never ever seen that in the past.’ This thing is amazing: a massive blob that you can browse. It’s so sporadic that you see all the galaxies behind it. It is actually a transparent galaxy.”

The ghostly galaxy does not have a visible main area, or perhaps spiral arms and a disk, normal functions of a spiral nebula. However it does not appear like an elliptical galaxy, either. The galaxy likewise reveals no proof that it houses a main great void. Based upon the colors of its globular clusters, the galaxy has to do with 10 billion years of ages. Even the globular clusters are oddballs: they are two times as big as normal excellent groupings seen in other galaxies.

” It resembles you take a galaxy and you just have the excellent halo and globular clusters, and it in some way forgot to make whatever else,” van Dokkum stated. “There is no theory that forecasted these kinds of galaxies. The galaxy is a total secret, as whatever about it is unusual. How you in fact set about forming among these things is entirely unidentified.”

However the scientists do have some concepts. NGC 1052- DF2 lives about 65 million light-years away in a collection of galaxies that is controlled by the huge elliptical galaxy NGC1052 Galaxy development is rough and violent, and van Dokkum recommends that the development of the recently established enormous galaxy billions of years ago maybe contributed in NGC 1052- DF2’s dark-matter shortage.

Another concept is that gas approaching the huge elliptical NGC 1052 might have fragmented and formed NGC 1052- DF2. The development of NGC 1052- DF2 might have been assisted by effective winds originating from the young great void that was growing in the center of NGC1052 These possibilities are speculative, nevertheless, and do not describe all the qualities of the observed galaxy, the scientists stated.

The group is currently searching for more dark-matter lacking galaxies. They are examining Hubble pictures of 23 other scattered galaxies. 3 of them appear just like NGC 1052- DF2.

” Every galaxy we understood about in the past has dark matter, and they all fall in familiar classifications like spiral or elliptical galaxies,” van Dokkum stated. “However exactly what would you get if there were no dark matter at all? Perhaps this is exactly what you would get.”


The group’s outcomes will appear in the March 29, 2018, concern of the journal Nature

The Hubble Space Telescope is a task of worldwide cooperation in between NASA and ESA (European Space Firm). NASA’s Goddard Space Flight Center in Greenbelt, Maryland, handles the telescope. The Space Telescope Science Institute (STScI) in Baltimore performs Hubble science operations. STScI is run for NASA by the Association of Universities for Research Study in Astronomy, Inc., in Washington, D.C.

For images and more details about galaxy NGC 1052- DF2 and Hubble, go to:

NASA’s Hubble Website: http://www.nasa.gov/hubble

The Nature paper: https://www.nature.com/articles/nature25767

HubbleSite link: http://hubblesite.org/news_release/news/2018-16

Donna Weaver/ Ray Villard .

Space Telescope Science Institute, Baltimore, Maryland .

410-338-4493/ 410-338-4514 .

[email protected]/ [email protected]

Pieter van Dokkum .

Yale University, New Sanctuary, Connecticut .

203-432-3019 .

[email protected] .

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