Shedding light on the faintest galaxies with the world's biggest steerable dish

May 23, 2018, Canadian Astronomical Society

Astronomers are one step closer to understanding a mysterious class of optically faint galaxies thanks to deep radio observations with the Green Bank Telescope, reveals a poster presented today at the Canadian Astronomical Society Annual Meeting in Victoria, British Columbia.

Surveys with optical telescopes have revealed that 'ultra diffuse '—enigmatic objects as big as the Milky Way but with only a small fraction of its stars—are abundant in and around galaxy groups and clusters. How ultra diffuse galaxies relate to Milky Way-type objects or to nearby dwarf galaxies is unknown, and progress in the optical is slow because of their extreme faintness. Instead, Professor Kristine Spekkens from the Royal Military College of Canada and her graduate student Ananthan Karunakaran from Queen's University are shedding light on this mysterious galaxy class through the eyes of the world's largest fully steerable radio .

Using deep observations with the Green Bank Telescope in West Virginia, Spekkens and Karunakaran discovered the atomic gas reservoirs—the stuff out of which stars ultimately form—associated with ultra diffuse galaxies around two compact galaxy groups. In contrast to the paucity of stars for their size, the gas content of ultra diffuse galaxies appears similar to that in other galaxies, while the gas motions suggest that they may be embedded in more extreme dark matter halos. These findings offer important clues to distinguish between competing theories for how ultra diffuse galaxies form, supporting a model in which their unusual properties stem at least in part from their dark matter contents.

Spekkens and Karunakaran have teamed up with Dennis Zaritsky at the University of Arizona to follow up dozens of newly-detected ultra diffuse galaxies around the Coma cluster with the Green Bank Telescope; this larger sample will allow the researchers to systematically explore correlations between the gaseous and stellar contents of these enigmatic objects for the first time. Their ultimate goal is to understand how the diversity of galaxies that we see in the universe today formed and evolved.

Explore further: A trace of galaxies at the heart of a gigantic galaxy cluster

More information: Kristine Spekkens et al. Atomic Gas in Blue Ultra Diffuse Galaxies around Hickson Compact Groups, The Astrophysical Journal (2018). DOI: 10.3847/1538-4357/aa94be ,

Related Stories

A trace of galaxies at the heart of a gigantic galaxy cluster

August 22, 2017

Very large yet faint galaxies have been found where no one would have expected them – in the middle of a giant galaxy cluster. Heidelberg astronomers discovered the extremely-low density galaxies, known as ultra-diffuse ...

Mystery of ultra-diffuse faint galaxies solved

November 28, 2016

Over the last year, researchers have observed some very faint, diffuse galaxies. The galaxies are as faint as dwarf galaxies, but are distributed over an area just as large as the Milky Way.

Dark matter 'missing' in a galaxy far, far away

March 28, 2018

Galaxies and dark matter go hand in hand; you typically don't find one without the other. So when researchers uncovered a galaxy, known as NGC1052-DF2, that is almost completely devoid of the stuff, they were shocked.

Image: Hubble catches galaxies swarmed by star clusters

October 2, 2017

In the center of a rich cluster of galaxies located in the direction of the constellation of Coma Berenices, lies a galaxy surrounded by a swarm of star clusters. NGC 4874 is a giant elliptical galaxy, about ten times larger ...

Scientists discover the fluffiest galaxies

May 14, 2015

An international team of researchers led by Pieter van Dokkum at Yale University have used the W. M. Keck Observatory to confirm the existence of the most diffuse class of galaxies known in the universe. These "fluffiest ...

Recommended for you

Archaeologists discover Incan tomb in Peru

February 16, 2019

Peruvian archaeologists discovered an Incan tomb in the north of the country where an elite member of the pre-Columbian empire was buried, one of the investigators announced Friday.

Where is the universe hiding its missing mass?

February 15, 2019

Astronomers have spent decades looking for something that sounds like it would be hard to miss: about a third of the "normal" matter in the Universe. New results from NASA's Chandra X-ray Observatory may have helped them ...

What rising seas mean for local economies

February 15, 2019

Impacts from climate change are not always easy to see. But for many local businesses in coastal communities across the United States, the evidence is right outside their doors—or in their parking lots.

The friendly extortioner takes it all

February 15, 2019

Cooperating with other people makes many things easier. However, competition is also a characteristic aspect of our society. In their struggle for contracts and positions, people have to be more successful than their competitors ...


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.