Scientists have spotted a pair of strange cosmic structures about a billion light-years away that have been dubbed "Dancing Ghosts" due to their unusual appearance.
The ghostly features are the result of a pair of supermassive black holes, each located at the heart of two radio galaxies, spewing out jets of electrons, which are being shaped by intergalactic winds in a peculiar way, according to a study accepted by the journal Publications of the Astronomical Society of Australia.
The strange clouds, which have never been seen before, were uncovered during the first wide and deep search conducted by The Commonwealth Scientific and Industrial Research Organisation's (CSIRO) Australian Square Kilometre Array Pathfinder (ASKAP) radio telescope.
The observations were conducted as part of the EMU (Evolutionary Map of the Universe) project, which began in 2009 and involves more than 400 scientists from over 20 countries.
"We are getting used to surprises as we scan the skies as part of the EMU Project, and probe deeper into the universe than any previous telescope," Ray Norris, lead author of the study from Western Sydney University and CSIRO—Australia's national science agency—said in a statement.
"When you boldly go where no telescope has gone before, you are likely to make new discoveries."
When the scientists first spotted the "Dancing Ghosts" in the data collected by ASKAP it was not immediately clear what they were seeing.
"Scanning through data fresh off the telescope, we saw two ghosts dancing deep in the cosmos. We had never seen anything like it before, and we had no idea what they were," Norris wrote in a piece for The Conversation.
"Several weeks later, we had figured out we were seeing two radio galaxies, about a billion light-years away. In the center of each one is a supermassive black hole, squirting out jets of electrons that are bent into grotesque shapes by an intergalactic wind."
Radio galaxies are a particular type of active galaxy that emit more light at radio wavelengths than at visible wavelengths. Intergalactic winds are streams of charged particles traveling at high speeds that are often seen being emitted by galaxies.
Norris told Newsweek that the "Dancing Ghosts" are the result of material falling into the black hole creating a region of high pressure and temperature outside the event horizon—the point beyond which nothing, not even light, can escape.
"It is this high pressure which squirts the beams of electrons out of the system," he said. "What we are actually seeing is radio waves produced by the electrons swirling around intergalactic magnetic fields. As each electron is bent from its path by the magnetic field, it releases energy that we see as radio waves. That's the easy bit. The hard bit is understanding how these jets of electrons get bent into these weird shapes."
Norris said that many more observations and computer modeling experiments will be needed to fully understand the "Dancing Ghosts" given that many questions, such as where the intergalactic wind is coming from, remain unanswered.
"New discoveries however always raise new questions and this one is no different. We still don't know where the wind is coming from? Why it is so tangled? And what is causing the streams of radio emission?" Norris said in the statement.
The discovery was made possible by the capabilities of the ASKAP telescope, which is located in the desert of Western Australia.
"No previous telescope would have been able to detect that faint diffuse emission or produce these images," Norris said. "We've spent 11 years planning for this, so naturally we're incredibly excited to see how well the telescope is performing."
Norris said the "Dancing Ghosts" are just one example of the "many strange new objects" that we have detected with the EMU Pilot Survey.
"We see many large diffuse structures in the survey that we haven't seen before, and these are going to challenge our understanding of the way that galaxies move and interact with the intergalactic medium and the cosmic web," he said.
