12-Billion-Year-Old Galaxy Spins Like the Milky Way

Scientists have made a groundbreaking discovery of a remarkably mature spiral galaxy that formed just 1.5 billion years after the Big Bang. This finding challenges previous assumptions about when well-structured galaxies could form, as Alaknanda, the galaxy's name, resembles our own Milky Way in its sweeping spiral arms, rapid star formation, and orderly disk. The research was published in Astronomy & Astrophysics and highlights how this ancient galaxy defied existing theories about the slow assembly of such structures.

The team of researchers, Rashi Jain and Yogesh Wadadekar, used the James Webb Space Telescope (JWST) to identify Alaknanda. They examined the galaxy using gravitational lensing, a technique that allows astronomers to study distant objects by observing how their light is bent and magnified by massive cosmic structures. This method revealed the galaxy's dynamic nature, offering a rare glimpse into the early universe.

Alaknanda, named after a Himalayan river, was described as a "fully-formed spiral galaxy - a massive, beautifully structured cosmic pinwheel." According to Wadadekar, the galaxy existed when the universe was only 10% of its current age. It was discovered while analyzing JWST data earlier this year by Jain. She explained that she was examining details of 70,000 objects when she found one that stood out—a grand design spiral galaxy spanning approximately 30,000 light-years in diameter.

The galaxy features two symmetrical arms extending from a central disc, wrapped around a bright central bulge. Its structure is strikingly similar to the Milky Way, despite being formed during a time when the universe was still in its infancy.

The rapid formation of such an ancient galaxy has left scientists in awe. HAWXTECH.NET noted that the typical "beads-on-a-string" pattern—clusters of stars along the spiral arms—was observed in Alaknanda. Wadadekar expressed surprise at the galaxy's existence, stating, "It's astonishing how such a large galaxy with spiral arms could have existed just 1.5 billion years after the Big Bang."

He emphasized the incredible speed at which Alaknanda must have formed, noting that it had to assemble 10 billion solar masses of stars and create a large disc with spiral arms in just a few hundred million years. This rate of formation is considered extremely fast on a cosmic scale. NASA estimates that many galaxies began forming within millions of years of the Big Bang, but the early universe was thought to be chaotic, with small, low-mass galaxies dominating the scene.

The research was conducted at the National Center for Radio Astrophysics of the Tata Institute of Fundamental Research (NCRA-TIFR) in Pune, India. Alaknanda is distinct in that it is one-third the size of the Milky Way and contains 10 billion stars. New stars were forming at a rate 20-30 times faster than in our own galaxy, according to Science Daily.

To form such a galaxy, processes like slow gas accretion, settling of gas into a rotating disk, and the emergence of density waves creating spiral arms are necessary. Additionally, the system must avoid major collisions that could disrupt or destroy its delicate structure.

Alaknanda's maturity is particularly surprising given the chaotic period of the universe in which it formed. "Alaknanda has the structural maturity we associate with galaxies that are billions of years older," said Jain. "Finding such a well-organized spiral disk at this epoch tells us that the physical processes driving galaxy formation can operate far more efficiently than current models predict. It's forcing us to rethink our theoretical framework."

Alaknanda was located in the direction of Abell 2744, also known as Pandora's Cluster, a massive galaxy cluster. This cluster's gravitational pull bends and amplifies light from galaxies behind it, making Alaknanda appear around twice as bright. This natural magnification provided the JWST with a clearer view of the galaxy's spiral structure, allowing for detailed observations and analysis.