Bologna, Italy — Astronomers have captured an unprecedented image of the galaxy cluster Abell 2255, revealing intricate details of its radio-emitting filaments. This cluster, situated approximately 800 million light-years from Earth and comprising between 300 and 500 galaxies, showcases a complex web of structures that offer new insights into galactic evolution.
Located about 16.3 million light-years across, Abell 2255 serves as a host to “radio galaxies,” characterized by supermassive black holes that eject jets of matter at astonishing speeds. These jets play a critical role in shaping the intergalactic medium—the space filled with gas and dust between galaxies—potentially influencing the formation and evolution of future galaxies.
Marco Bond, a researcher at the National Institute for Astrophysics, emphasized that the findings might redefine how we study both radio galaxies and the surrounding gas. “These results open the way to new perspectives for understanding the properties of the gas that permeates galaxy clusters,” he noted.
The research team utilized the European Low Frequency Array (LOFAR) radio telescope in its Very Long Baseline Interferometry mode, conducting 56 hours of observations at a frequency of 144 MHz. This effort produced high-resolution images with an angular detail of up to 0.3 arcseconds, allowing astronomers to observe elongated structures stretching anywhere from 260,000 to 360,000 light-years—over three times the Milky Way’s width. Remarkably, these filaments are also less than a tenth as thick as our galaxy.
Researchers believe these filaments likely originate from the radio galaxies within Abell 2255, pulled outward by turbulent forces within the cluster. Eventually, they will blend into the intergalactic medium, further enriching the material found between galaxies.
Among the radio galaxies studied, one notable example is the Original Tailed Radio Galaxy, which features a convoluted tail and rich filamentary structures. The new observations have also shed light on other radio galaxies in Abell 2255, such as the Goldfish, Beaver, and Embryo galaxies, each distinguished by their unique shapes and extensive trailing radio emissions that exceed 200,000 light-years.
Emanuele De Rubeis, a member of the research team from the University of Bologna, explained that the primary goal was to identify filaments in the radio galaxy tails to better understand their origins and morphological characteristics. “Modern interferometers, like those advancing the SKA project, are increasingly revealing these phenomena and offering valuable opportunities to investigate the magnetic properties of hot gas within clusters and the mechanisms for particle acceleration,” he stated.
This research is part of broader efforts enhanced by strides in LOFAR-VLBI calibration techniques. Each night of data collection yielded around 4 terabytes of raw data, which, upon calibration, ballooned to between 18 and 20 terabytes per night, culminating in an impressive total of about 140 terabytes.
The complexity of calibrating and processing this data required substantial effort, with the team taking an average month to generate quality images from a single night of observations. Their research findings were published in the journal Astronomy & Astrophysics on June 10, marking a significant milestone in studying galactic structures and evolution.