(ORDO NEWS) — The universe is filled with magnetic fields. Although the universe is electrically neutral, atoms can be ionized into positively charged nuclei and negatively charged electrons.
When these charges are accelerated, they create magnetic fields.
One of the most common sources of magnetic fields on a large scale are collisions between and within interstellar plasma. It is one of the main sources of magnetic fields for galactic-scale magnetic fields.
But magnetic fields must also exist on even larger scales. On the largest scale of the cosmos, matter is distributed in a structure known as the cosmic web.
Large superclusters of galaxies are separated by barren voids, like accumulations of soapy water among a vast area of soap bubbles.
Thin threads of intergalactic material are stretched between these superclusters, creating a cosmic web of matter.
Much of this network is ionized, so it must create extensive but weak intergalactic magnetic fields. At least that’s the theory.
Astronomers have been unable to observe these weblike magnetic fields. But a new study has made the first detections of them.
We cannot directly detect magnetic fields that are billions of light years away. Instead, we observe them through their effect on charged particles.
When electrons and other particles spiral along magnetic field lines, they emit radio light.
By matching this radio signal, astronomers can map the galactic magnetic fields. But the strands of the cosmic web are so scattered that the radio light they emit is very weak.
Too weak to be easily detected. And because nearby galaxies create even stronger radio signals, the web’s signal could be drowned out by galactic radio noise.
To solve this problem, the team focused on polarized radio emission. These are radio emissions that have a certain directionality.
Since the orientation is related to the overall orientation of the filament, it was easier for the team to isolate this signal from the space radio background.
They used data from all-sky radio maps such as the Global Magneto Ionic Survey, the Planck Legacy Archive, the Owens Valley Longwave Array, and the Murchison Widefield Array.
By correlating this data and comparing it to maps of the comic web, the team confirmed the polarized radio signal emitted by the web.
This result is not only the first detection of magnetic fields in the cosmic web, but also strong evidence for the existence of collision shock waves within intergalactic filaments.
These shock waves have been seen in computer simulations of cosmic structures, but this is the first evidence to support the idea that these simulation features are accurate.
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