A rare discovery has been made by two astronomers from the Inter-University Centre for Astronomy and Astrophysics (IUCAA) Pune, named professor Vaidehi S Paliya and professor Dhruba J Saikia. They recently identified a gamma-ray emitting collisional ring galaxy system located just 30 million light years away from the Milky Way. This unique structure, named ‘Kathryn’s Wheel’, is formed when a smaller ‘bullet’ galaxy penetrates through a larger galaxy near its center, producing a shockwave that pushes the interstellar gas out of the system, resulting in a ring of star-forming regions and a gas-poor galaxy. Such systems are rare, with the Cartwheel galaxy being the best example. The research titled “A gamma-ray emitting collisional ring galaxy system in our galactic neighbourhood” has been published in the prestigious “Astrophysical Journal Letters”.
The observations of ‘Kathryn’s Wheel’ in radio, optical, and ultraviolet wavelengths have unveiled intense star-forming activities surrounding the central spiral galaxy, potentially triggered by the galaxy collision. The ‘bullet’ galaxy itself is experiencing rapid star formation, showcasing the dynamic nature of these cosmic events. Professor Paliya highlighted the importance of photons in unraveling cosmic mysteries, with gamma-ray photons being the most energetic form originating from extreme astrophysical environments like supernovae explosions and regions around black holes.
‘Kathryn’s Wheel’, although situated in our galactic vicinity, has been under-studied due to the presence of a bright nearby star and its location in a challenging region close to the galactic plane with extreme dust obscuration. This galaxy provides an opportunity to explore the origin and transport of cosmic rays, showcasing a connection with star-forming activities due to its proximity to the Milky Way. The gamma-ray radiation detected from ‘Kathryn’s Wheel’ is believed to be a result of star-forming processes, indicating the significance of high-resolution, multiwavelength observations to uncover hidden astrophysical treasures in the cosmos.
This groundbreaking discovery marks the first-ever identification of a collisional ring galaxy system detected in the gamma-ray band, emphasizing the necessity of detailed observations to unveil the mysteries of the universe. With further studies, the enigmatic ‘Kathryn’s Wheel’ presents a unique opportunity to comprehend cosmic ray interactions, star formation mechanisms, and the impact of galaxy collisions on the evolution of galaxies.
