Nikhuli's Cosmic Journey: Naga-Inspired Star Cluster Aids Black Hole Discovery in NGC 4424

In a groundbreaking astronomical discovery, NASA’s Chandra X-ray Observatory and the Hubble Space Telescope have identified a potential delivery system for black holes in the galaxy NGC 4424, located 54 million light-years away in the Virgo galaxy cluster. This discovery features an intriguing cluster of stars, nicknamed “Nikhuli,” which derives its name from the Sumi language, signifying the Tulini festive period celebrated in Nagaland , India. The findings were detailed in a paper published in the December 2021 issue of The Astrophysical Journal.

The inset image of NGC 4424 showcases Chandra X-ray data in blue alongside optical data in red, which has been adjusted to highlight faint features. This close-up view spans approximately 1,700 light-years, drawing attention to Nikhuli, an elongated red object interpreted by researchers as a cluster of stars. 

Nikhuli’s Naga Connection:

Nikhuli’s designation is particularly meaningful, linking the cosmos with cultural heritage, as Minister Abu Metha of Nagaland expressed excitement on Twitter: “NIKHULI – A Naga name 54 million light-years away. An astronomical research breakthrough by NASA; gets a proud Naga name from the Sumi community – a tribe known for their brave warriors. Many many moons from today, our future generations may make ‘contact’ or even visit Nikhuli!! Imagine celebrating Tuluni there!!”

A Galactic Collision and the Fate of Nikhuli

Researchers have theorized that Nikhuli likely represents the center of a small galaxy that has lost most of its stars during a collision with the larger galaxy NGC 4424. As it approaches the center of NGC 4424, Nikhuli has been stretched by gravitational forces, contributing to its elongated shape. Currently, Nikhuli is situated about 1,300 light-years from the center of NGC 4424, significantly closer than the Earth’s proximity to the Milky Way's giant black hole.

The Chandra data reveal a point source of X-rays, suggesting a potential explanation for its origin. Researchers propose that matter from Nikhuli may be rapidly falling into a stellar-mass black hole. However, due to the expected rarity of such smaller black holes in a cluster like Nikhuli, the authors lean toward the idea that the X-ray emissions are from material gradually falling onto a more massive black hole, estimated to be between 40,000 and 150,000 solar masses. This mass aligns with the anticipated size of the black hole located at the center of NGC 4424.

This study suggests that Nikhuli may act as a conduit for supplying black holes to NGC 4424, potentially delivering a massive black hole as it orbits the larger one. Over time, the distance between these two black holes is expected to diminish, leading to the production of gravitational waves as they merge. This cosmic event could have significant implications for our understanding of galaxy formation and evolution.

The collaboration between astronomers across the globe, including Alister Graham from Swinburne Astronomy Online, Roberto Soria from the University of the Chinese Academy of Sciences, and others, highlights the fusion of science and culture. As Nikhuli's story unfolds, it serves as a reminder of the connections between our cultural heritage and the vastness of the universe, inspiring future generations to explore the cosmos.