Over the past five years, astronomers have discovered a new type of astronomical phenomenon that exists on large scales — larger than entire galaxies. Called ORCs (individual radio circuits), they look like giant rings of radio waves expanding outward like a shock wave.
Until now, ORCs have never been observed at any wavelength other than radio, but according to a new… paper Released on April 30, 2024, astronomers captured X-rays associated with ORC for the first time.
This discovery provides some new clues about what may be behind the creation of the ORC.
While many astronomical events, such as supernova explosions, can leave behind circular remnants, ORCs seem to require a different explanation.
“The energy needed to produce such an extended radio emission is very powerful,” said Israa Bulbul, lead author of the new research. “Some simulations can reproduce their shapes but not their densities. There are no simulations that explain how ORCs are created.”
ORCs can be a challenge to study, in part because they are usually only visible at radio wavelengths. They have not previously been linked to X-ray or infrared emission, and there has been no sign of them at optical wavelengths.
Sometimes, ORCs surround a visible galaxy, but not always (eight have been discovered so far around known elliptical galaxies).
Using ESA’s XMM-Newton telescope, Bulbul and her team observed one of the closest known ORCs, an object called Cloverleaf, and found a striking X-ray component of this object.
“This is the first time anyone has seen the X-ray emission associated with an ORC,” Bulbul said. “It was the missing key to unlocking the secret of the Cloverleaf Formation.”
An X-ray of a clover leaf shows a gas that has been heated and moved by some process. In this case, the X-ray emissions reveal two clusters of galaxies (about a dozen galaxies in total) that have begun to merge inside the cloverleaf, heating the gas to 15 million degrees Fahrenheit.
Chaotic galaxy mergers are interesting, but they can’t explain a cloverleaf on their own. Galaxy mergers occur throughout the universe, while ORCs are a rare phenomenon. There’s something unique going on to create something like Cloverleaf.
“Merger processes form the backbone of structure formation, but there is something special about this system that triggers radio emission,” Bulbul said. “We can’t know now what it is, so we need more and deeper data from both radio and X-ray telescopes.”
This doesn’t mean astronomers don’t have any guesses.
“One fascinating insight into the strong radio signal is that resident supermassive black holes went through episodes of intense activity in the past, and the remaining electrons from this ancient activity were re-accelerated by this fusion event,” NASA project scientist Kim Weaver told XMM. -Newton.
In other words, ORCs like Cloverleaf may require a two-part origin story: powerful emissions from active, supermassive black holes, followed by galaxy merger shockwaves that give those emissions a second boost.
This article was originally published by The universe today. is reading Original article.
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