The mysterious structures in the sky that have shocked astronomers for decades may finally have an explanation, and it is quite a bit.
The spur of the north pole and the fan region, on opposite sides of the sky, can be connected by a vast system of magnetized filaments. They form a tunnel-like structure that orbits the Solar System, as well as several nearby stars.
“If we were to roll our eyes,” said astronomer Jennifer West about the University of Toronto in Canada, “we would see this structure like a tunnel in almost every direction we look, that is, if we had eyes that could see the radio. light ”.
We’ve known the two structures for some time, from the 1960s actually, but they were hard to understand. This is because it is really difficult to understand exactly how far they are; distances range from hundreds to thousands of light years away.
However, no analysis had linked the two structures. West and his colleagues were able to show that the two regions and the major radio circuits in the space between them can be linked, solving many of the puzzling problems associated with the two.
“A few years ago, one of our co-authors, Tom Landecker, told me about a 1965 article about the early days of radio astronomy. Based on the raw data available at the time, the authors (Mathewson & Milne) speculated that these polarized radio signals could be derived from our view of the galaxy’s Local Arm, from within. , “West explained.
“That paper inspired me to develop this idea and combine my model with the much better data that our telescopes provide us today.”
Using models and simulations, the researchers discovered what the radio sky looks like if the two structures were connected by magnetic filaments, and played with parameters such as distance to determine the optimal position.
From this, the team was able to determine that the most likely distance to the structures in the Solar System is about 350 light-years, consistent with some of the closest estimates. This includes an estimate of the distance to the northern polar spur earlier this year based on data from Gaia, which found that almost the entire spur is within 500 light-years.
The total length of the tunnel modeled by West and his team is about 1,000 light years.
This model is consistent with a wide range of observation of the properties of the northern polar spur and fan region, including the shape, polarization of electromagnetic radiation (i.e. how waves rotate). ), and brightness.
“This is an extremely smart job,” said astronomer Bryan Gaensler of the University of Toronto.
“When Jennifer first proposed to me, I thought there was too much ‘there’ to be a possible explanation. But in the end he managed to convince me! I am now excited to see how the rest of the astronomical community reacts. “
More work is needed to first confirm the results and then model the structure in more detail. But doing so can help solve an even bigger mystery: the formation and evolution of magnetic fields in galaxies and how these fields are maintained. The researchers said it could also provide a context for understanding other magnetic filamentary structures found around the galaxy.
The team plans to run more complex models; but, they suggest, higher resolution and more sensitive observations help to reveal hidden details that show how the structure fits into the larger galactic context.
“Magnetic fields do not exist in isolation. All have to connect with each other. So the next step is to better understand how this local magnetic field connects to both the large-scale galactic magnetic field, and the smaller-scale magnetic fields of our Sun and Earth, ”West said.
“I think it’s nice to imagine that these structures are everywhere, every time we look at the night sky.”
Your search should appear in it The Astrophysical Journal, and is available in arXiv.
Cover Image Credit: Dominion Radio Astrophysical Observatory / Villa Elisa Telescope / ESA / Planck Collaboration / Stellarium / J. West