Discovery of two potential Polar Ring galaxies suggests these stunning rare clusters might be more common than previously believed

A group of international astronomers, including researchers from Queen's University, has identified two potential polar ring galaxies, according to results published today in the Monthly Notices of the Royal Astronomical Society.

Queen's researchers Nathan Deg and Kristine Spekkens (Physics, Engineering Physics & Astronomy) led the analysis of data obtained using a telescope owned and operated by CSIRO, Australia's national science agency. Looking at sky maps of hydrogen gas in over 600 galaxies as part of CSIRO's ASKAP radio telescope's WALLABY survey, they identified two potential polar ring galaxies, a type of galaxy that exhibits a ring of stars and gas perpendicular to its main spiral disk.

Although this is not the first time that astronomers have observed polar ring galaxies, they are the first observed using the ASKAP telescope located at Inyarrimanha Ilgari Bundara, CSIRO's Murchison radio astronomy observatory on Wajarri Yamaji Country in Western Australia.

These new detections in gas alone suggest polar ring galaxies might be more common than previously believed.

Understanding how galaxies evolve

Further investigation of polar ring structures can help us better understand how galaxies evolve. For example, one of the main hypotheses to explain the origin of polar rings is a merger where a larger galaxy 'swallows' a smaller one. If polar ring galaxies are more common than previously thought, this could mean that these mergers are more frequent.

In the future, polar ring galaxies can also be used to deepen our understanding of the universe, with potential applications in dark matter research. It is possible to use polar rings to probe the shape of dark matter of the host galaxy, which could lead to new clues about the mysterious properties of the elusive substance.

Visualizing polar ring galaxies

Jayanne English, a member of the WALLABY research team and also an expert in astronomy image-making at the University of Manitoba, developed the first images of these gaseous polar ring galaxies using a combination of optical and radio data from the different telescopes. First, optical and infrared data from the Subaru telescope in Hawaii provided the image for the spiral disk of the galaxy. Then, the gaseous ring was added based on data obtained from the WALLABY survey, an international project using CSIRO's ASKAP radio telescope to detect atomic hydrogen emission from about half a million galaxies.

The creation of this and other astronomical images are all composite because they include information that our eyes can't capture. In this particular case, the cold hydrogen gas component, invisible to the human eye, is seen in radio "light" using CSIRO's ASKAP. The subtle colour gradient of this ring represents the orbital motions of the gas, with purple-ish tints at the bottom tracing gas that moves towards the viewer while the top portion moves away. The emission from the ring was separated from the radio emission emanating from the disk of the galaxy using virtual reality tools, in collaboration with Professor Tom Jarrett (University of Cape Town, South Africa).

Over 25 global collaborators from Canada, Australia, South Africa, Ecuador, Burkina Faso, Germany, China, and beyond worked together to analyze the data from the first public data release of the WALLABY survey, resulting in the newly published paper.

The next step for the team is to confirm the polar ring galaxies finding through additional observations using different telescopes, including the MeerKAT radio telescope in South Africa.

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Fear is in the eye of the beholder

Averting our eyes from things that scare us may be due to a specific cluster of neurons in a visual region of the brain, according to new research at the University of Tokyo. Researchers found that in fruit fly brains, these neurons release a chemical called tachykinin which appears to control the fly's movement to avoid facing a potential threat. Fruit fly brains can offer a useful analogy for larger mammals, so this research may help us better understand our own human reactions to scary situations and phobias. Next, the team want to find out how these neurons fit into the wider circuitry of the brain so they can ultimately map out how fear controls vision.

Do you cover your eyes during horror movies? Or perhaps the sight of a spider makes you turn and run? Avoiding looking at things which scare us is a common experience, for humans and animals. But what actually makes us avert our gaze from the things we fear? Researchers have found that it may be due to a group of neurons in the brain which regulates vision when feeling afraid.

"We discovered a neuronal mechanism by which fear regulates visual aversion in the brains of Drosophila (fruit flies). It appears that a single cluster of 20-30 neurons regulates vision when in a state of fear. Since fear affects vision across animal species, including humans, the mechanism we found may be active in humans as well," explained Assistant Professor Masato Tsuji from the Department of Biological Sciences at the University of Tokyo.

The team used puffs of air to simulate a physical threat and found that the flies' walking speed increased after being puffed at. The flies also would choose a puff-free route if offered, showing that they perceived the puffs as a threat (or at least preferred to avoid them). Next the researchers placed a small black object, roughly the size of a spider, 60 degrees to the right or left of the fly. On its own the object didn't cause a change in behavior, but when placed following puffs of air, the flies avoided looking at the object and moved so that it was positioned behind them.

To understand the molecular mechanism underlying this aversion behavior, the team then used mutated flies in which they altered the activity of certain neurons. While the mutated flies kept their visual and motor functions, and would still avoid the air puffs, they did not respond in the same fearful manner to visually avoid the object.

"This suggested that the cluster of neurons which releases the chemical tachykinin was necessary for activating visual aversion," said Tsuji. "When monitoring the flies' neuronal activity, we were surprised to find that it occurred through an oscillatory pattern, i.e., the activity went up and down similar to a wave. Neurons typically function by just increasing their activity levels, and reports of oscillating activity are particularly rare in fruit flies because up until recently the technology to detect this at such a small and fast scale didn't exist."

By giving the flies genetically encoded calcium indicators, the researchers could make the flies' neurons shine brightly when activated. Thanks to the latest imaging techniques, they then saw the changing, wavelike pattern of light being emitted, which was previously averaged out and missed.

Next, the team wants to figure out how these neurons fit into the broader circuitry of the brain. Although the neurons exist in a known visual region of the brain, the researchers do not yet know from where the neurons are receiving inputs and to where they are transmitting them, to regulate visual escape from objects perceived as dangerous.

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