The universe is filled with clusters of galaxies – massive structures stacked at the intersections of planets. cosmic web. A single cluster can span millions of light years and consist of hundreds or even thousands of galaxies.
However, these galaxies represent only a few percent of a cluster’s total mass. About 80 percent of this dark matterand the rest is a “soup” of hot plasma: gas heated to over 10,000,000℃ and teeming with weak magnetic fields.
We and our team of international colleagues have identified a number of rarely observed radio objects, including a radio remnant, a radio halo, and fossil radio emission, within a particularly dynamic galaxy cluster called Abell 3266. objects and their properties.
(Using data from Christopher Riseley, ASKAP, ATCA, XMM-Newton and Dark Energy Survey)
Above: ASKAP and ATCA (red/orange/yellow colors), XMM-Newton (blue), and the Abell 3266 cluster colliding as seen in the electromagnetic spectrum dark energy Survey (background map).
Relics, halos and fossils
Galaxy clusters allow us to study a wide variety of rich processes, including magnetism and plasma physics, in environments that we cannot recreate in our laboratories.
When the clusters collide with each other, large amounts of energy are given to the particles of the hot plasma, producing radio emission. And this emission comes in a variety of shapes and sizes.
“Radio remains” is an example. They are arc-shaped and sit at the outskirts of a cluster, supported by shock waves that travel through the plasma that causes a jump in density or pressure and energizes the particles. An example of a shock wave on Earth is the sonic boom that occurs when an aircraft breaks through the sound barrier.
“Radio halos” are irregular sources extending towards the center of the cluster. They are powered by turbulence in the hot plasma that energizes the particles. We know that both halos and remnants are formed by collisions between galaxy clusters – yet many of their gritty details are incomprehensible.
Then there are the “fossil” radio sources. These are radio remnants left over from the death of a supermassive black hole at the center of a radio galaxy.
When they are in action, black holes shoot giant jets of the plasma far beyond the galaxy itself. As their fuel runs out, the jets begin to disperse. The remains are what we identify as radio fossils.
Abell 3266
Ours new paperPosted in Monthly Notices of the Royal Astronomical SocietyIt offers a very detailed study of a galaxy cluster called Abell 3266.
This is a particularly dynamic and diffuse collision system about 800 million light-years away. It has all the distinguishing features of a system. should host relics and halos – but none have been detected until recently.
follow-up of the work carried out using Murchison Wide Field Array earlier this yearWe used new data from . ASKAP radio telescope and Australian Telescope Compact Array (ATCA) To see the Abell 3266 in more detail.
Our data paints a complex picture. You can see this in the main picture: the yellow colors show the features where the energy input is active. Blue haze represents hot plasma captured at X-ray wavelengths.
Redder colors indicate features that can only be seen at lower frequencies. This means that these objects are older and have less energy. Either they lost a lot of energy over time or they never had much to begin with.
Radio remnant appears in red near the bottom of the image (see below for zoom). And our data here reveal certain features never before seen in a relic.
(Using data from Christopher Riseley, ASKAP, ATCA, XMM-Newton and Dark Energy Survey)
Above: The ‘wrong path’ remnant in Abell 3266 is shown here in yellow/orange/red representing radio luminosity.
Its concave shape is also unusual, earning it the catchy nickname of a “wrong way” relic. Overall, our data distorts our understanding of how artifacts are produced, and we’re still trying to decipher the complex physics behind these radio objects.
Ancient remains of a supermassive black hole
The radio fossil seen in the upper right of the main image (and also below) is very faint and red, indicating that it is ancient. We believe this radio emission originally came from the lower left galaxy, a central black hole that has been closed for a long time.
(Using data from Christopher Riseley, ASKAP, ATCA, XMM-Newton and Dark Energy Survey)
Above: The radio fossil from Abell 3266 is shown with red colors and contours indicating the radio luminosity measured by ASKAP, and blue colors indicating hot plasma. The cyan arrow points to the galaxy that we think once powered the fossil.
Our best physical models don’t fit in the data. This reveals gaps in our understanding of how these resources evolved – the gaps we are trying to fill.
Finally, using a clever algorithm, we defocused the main image (see below) to look for the very weak emission invisible at high resolution, revealing the first detection of a radio halo in the Abell 3266.
(Using data from Christopher Riseley, ASKAP, ATCA, XMM-Newton and Dark Energy Survey)
Above: The radio halo in Abell 3266 is shown with red colors and contours indicating the radio luminosity measured by ASKAP, and blue colors indicating hot plasma. The dashed cyan curve shows the outer boundaries of the radio halo.
towards the future
This is the beginning of the path to understanding Abell 3266. We uncovered a wealth of new and detailed information, but our study raised even more questions.
The telescopes we use lay the foundations of revolutionary science. Square Kilometer Array project. Research like ours allows astronomers to understand things we don’t – but rest assured we will.
We acknowledge the Gomeroi people as the traditional owners of the area where the ATCA is located, and the Wajarri Yamatji people as the traditional owners of the Murchison Radioastronomy Observatory area where the ASKAP and Murchison Wide Field Array are located. 
Christopher Riseleyresearch assistant, University of Bologna and Tessa Wernstromsenior research fellow, University of Western Australia.
This article has been republished from: Speech Under Creative Commons license. To read original article.
