Untangling a knot of galaxy clusters

Astronomers have captured a spectacular, ongoing collision between a minimum of three galaxy clusters. Knowledge from NASA’s Chandra X-ray Observatory, ESA’s (European House Company’s) XMM-Newton, and a trio of radio telescopes helps astronomers type out what is going on on this jumbled scene. Collisions and mergers like this are the primary approach that galaxy clusters can develop into the big cosmic edifices seen right now. These additionally act as the most important particle accelerators within the universe.

The enormous galaxy cluster forming from this collision is Abell 2256, positioned 780 million light-years from Earth. This composite picture of Abell 2256 combines X-rays from Chandra and XMM in blue with radio information collected by the Big Metrewave Radio Telescope (GMRT), the Low Frequency Array (LOFAR), and the Karl G. Jansky Very Massive Array (VLA) all in purple, plus optical and infrared information from Pan-STARRs in white and pale yellow.

Astronomers finding out this object are attempting to tease out what has led to this unusual-looking construction. Every telescope tells a special a part of the story. Galaxy clusters are a few of the greatest objects within the universe containing a whole lot and even 1000’s of particular person galaxies. As well as, they comprise huge reservoirs of superheated fuel, with temperatures of a number of million levels Fahrenheit. Solely X-ray telescopes like Chandra and XMM can see this scorching fuel.

The radio emission on this system arises from an much more advanced set of sources. The primary are the galaxies themselves, through which the radio signal is generated by particles blasting away in jets from supermassive black holes at their facilities. These jets are both capturing into space in straight and slim traces (these labeled “C” and “I” within the annotated picture, utilizing the astronomer’s naming system) or slowed down because the jets work together with fuel they’re working into, creating advanced shapes and filaments (“A”, “B,” and “F”). Supply F accommodates three sources, all created by a black hole in a galaxy aligning with the left-most supply of this trio.

Radio waves are additionally coming from big filamentary buildings (labeled “relic”), largely positioned to the north of the radio-emitting galaxies, doubtless generated when the collision created shock waves and accelerated particles within the fuel throughout over two million light-years. A paper analyzing this construction was revealed earlier this yr by Kamlesh Rajpurohit from the College of Bologna in Italy within the March 2022 situation of The Astrophysical Journal. That is Paper I in an ongoing collection finding out totally different points of this colliding galaxy cluster system.

Lastly, there’s a “halo” of radio emission positioned close to the middle of the collision. As a result of this halo overlaps with the X-ray emission and is dimmer than the filamentary construction and the galaxies, one other radio picture has been produced to emphasise the faint radio emission. Paper II led by Rajpurohit, not too long ago revealed within the journal Astronomy and Astrophysics, presents a mannequin that the halo emission could also be attributable to the reacceleration of particles by fast adjustments within the temperature and density of the fuel because the collision and merging of the clusters proceed. This mannequin, nonetheless, is unable to elucidate all of the options of the radio information, highlighting the necessity for extra theoretical research of this and comparable objects.