Cosmic glow 10 billion light-years away reveals high-energy activity

Scientists have detected a giant cloud of high-energy particles, known as a mini-halo, surrounding a distant galaxy cluster located 10 billion light-years away. This discovery, made using the Low Frequency Array (LOFAR)—a powerful radio telescope with 100,000 antennas across Europe—marks the most distant observation of such a structure. The mini-halo emits faint radio waves across a million light-years, indicating that energetic particle activity was already prevalent in the universe when it was less than a third of its current age. This challenges previous assumptions that such high-energy processes occurred only later in cosmic history. The origin of these particles is still under investigation, but researchers propose two main sources: jets of high-energy particles emitted by supermassive black holes at the centers of cluster galaxies, or collisions among particles within the hot gas permeating the cluster. Both mechanisms suggest that energetic particles have influenced galaxy cluster evolution for billions of years longer than previously thought. This finding provides new insights into the role of black